Bose L1 Tower PA Repair

This is a repair of Bose L1 tower PA system. These skinny tower speakers are somewhat of a marvel because they are designed to stand behind the musician (aimed RIGHT AT the microphone) and don’t generate feedback (in most situations). Ah, the miracles of DSP.

It turns out these PA’s have a frequent failure in their power supply. Read on for details.

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1st generation Bose L1 tower PA system

UPDATE 10/22/2021: Since I first published this, I’ve gotten a lot of inquiries from people regarding repairing their L1s. For people local to northern CA, I’ve swapped working units for their bad ones plus cash. Then I try to fix the dead one I took in trade. All together now I’ve worked on five units and succeeded fixing all of them. I’ve also successfully repaired an aux supply board that someone extracted from their L1 and sent to me (Unit 3 below). For those trying repairs at home, here are my results (I’ll try to update as I see more units):

6 of 7 failures have been in the “Auxiliary Power Supply Board” (read below for more details). I recommend starting trouble shooting there if you L1 does not power up but please note the dangers of troubleshooting circuits that are hot to the AC line (noted elsewhere in this post).

Unit 1: My first attempted repair which started this blog post – D608 open – REPAIRED

Unit 2: D601 and D608 bad – REPAIRED

Unit 3: D601 bad – REPAIRED

Unit 4: D609 bad but also Transformer T601 open between pins 6 and 8. I was lucky in finding a broken wire that was accessible outside the windings. I reconnected the wire with some very carefully soldering. – REPAIRED

Unit 5: Had a working Aux Supply, but no sound from one half of the tower. The +/-27 power supply (there are three) for that channel power amp had smoked MOSFETs and other components. I harvested a +/-27V module from Unit 4 to get this one out the door, then repaired the supply by replacing two MOSFETs, two zeners, several resistors, and one rectifier.

Unit 6: A bit of a train wreck with many visibly charred components. I ultimately had to replace D606, D602, D614, Q601, R614, R620, R621, SCR601, TH603 and Z601. Whew! But now back from the dead. – REPAIRED

Unit 7: replaced D602 and D607 – REPAIRED

Tally so far on L1 repair is 7 for 7! 

Back to the original blog post:

The tower speakers slide into the base where they are both supported and electrically connected to the amplifier. All the circuitry is in the base.

The bad news is if you have a problem with this first generation L1 (ours is about 10 years old), Bose is zero help. They will no longer repair them and only implore you to get a new system. To make matters worse they are completely uncooperative about supplying schematics (though I was able to find documentation on-line).

Our L1 suffered a power supply failure, which is apparently fairly common as these units age. The culprit is the “Aux Power Supply” shown in the block diagram at this link.

Bose L1 Block Diagram

The below linked doc has schematics and instructions for disassembly. Even though it provides guidance, I still recommend taking LOTs of pictures. Especially of where connectors plug in.

Bose PS1-L1 rev1 Schematics

Dissembling the base is no small task. There are screws everywhere, and you have to pull almost everything apart to get at anything useful. Below shows the top cover and control panel PCB after unplugging from the power chassis.

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Top cover and control panel after disconnecting from power chassis
IMG_5529
Internal power chassis removed. Power stuff is in here. Note the four fans.

Pull the U-shaped top cover and you are in.

Bose aux locationI pulled out the Aux Power Supply board (upper right corner) and the EMI filter board (lower right corner) in order to troubleshoot the power supply on the bench.

HUGE WARNING! The EMI filter board and large parts of the Aux power supply are NOT isolated from the AC line! I powered this from an isolation transformer before hooking an oscilloscope. Make sure you fully understand what this means before proceeding with any testing. Unisolated circuits are VERY dangerous to work on.

Warning #2! The output of the EMI board is about 330V and the big capacitors on that board can store that voltage for up to 30 minutes time after the base is unplugged. Check that the voltage has fallen to a safe level (<20V) before touching anything or removing any boards.

IMG_5534

Aux power supply board

IMG_5535
Aux power supply back. Note that everything on the left side of this board is HOT TO THE AC LINE when input power is connected.

I found some unrectified AC waveforms in places that should have been DC, and pinpointed the problem to a large rectifier diode that was open-circuit. After replacing this diode, all the Aux rails powered up, but many voltages were off  (by 5V or more) from the spec’d values. I spent several days chasing this with no progress, until I guessed that the amplifier and the rest of the L1 circuitry might need to be connected to the Aux rails before they would read the correct voltages. This turned out to be correct. When I assembled and temporarily wired everything together, the Aux voltages read correctly. These rails are not tightly regulated and needed the load of the circuitry to pull them to their proper voltages.

Other miscellaneous inside images below, mostly to remind me where all the connectors go:

IMG_5533IMG_5526IMG_5527IMG_5525

IMG_5524
Control panel view of some connectors that must be removed before the power chassis can be separated from the main body.

IMG_5523IMG_5522

IMG_5521
Back of control panel close up
IMG_5520
Back of control panel close up
IMG_5518
Back of control panel
IMG_5519
Internal base plate for the tower support and speaker connector

133 thoughts on “Bose L1 Tower PA Repair

  1. We had an issue with our house PS1 sound system, coincidentally also 10yrs old. 3 years of faultless performance followed by an amp which failed to power up immediately when switched on….sometimes it would be 5 mins or up to an hour or two before the green led would light up .
    Hopefully this will be resolved with your help and a fabulously knowlegible friend. I’ll keep you updated. Bose were unsympathetic to the point that I felt like a cheapskate nuisance even enquiring about repair & all but told me to throw my PS1 in the trash and buy a new rig!! Watch this space for the next news

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    • Hi, Sorry for the delayed reply. I’m new to WordPress and don’t think I got notified of your comment. The symptoms are similar to mine, however we didn’t have any period where it worked for minutes before failing. It just didn’t turn-on one day. The Aux supply is still a likely culprit, but the problem is that this is thing is a bear to open-up and has a lot of messy “spaghetti” wiring and connectors to keep track of. I’m sure your friend knows that the first thing to check are the power supply voltages. It’s almost certain that some are off. Then the chase is to figure out if the cause is a dead capacitor or something else. good luck.

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  2. I have three classic L1’s that have failed now. Its not just the power supply failing, sometimes its an amp. I was able to rewire one L1 so it’s the same as the ones with two amps instead of the three.. Trying to figure a new amp to power the “sticks” and use as side fill speakers. I see these sticks for sale all the time now. There must be a easy set up with a small amp?

    Thoughts??

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    • I suppose it’s possible to gut the base and replace the electronics with your own, like maybe amps from Parts Express, but I think there would be a significant sound change. Though as a last resort, it might be worth a try.

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  3. Hi, I have the same problem (will not power up) and was wondering if I could pay you to repair my unit. I love this system. I tried the newer model and simply do not like the sound. Much more harsh and feedback prone.

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  4. Hi. You put some work into that. I wanted to point out though, you never did identify what part needed replacing! Anyone less knowledgeable about electronics but handy with a multimeter and soldering iron could probably do the same repair, if they knew where to look. If not actually marking the culprit on the picture, I’m sure some people would appreciate at least identifying the board stencil ID (D123? Z456? etc.) and maybe diode spec., if only for an idea of what to check first on their unit.

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  5. I have 4 of these units 2 of the original (3 amp) and 2 of the later (2 amp) versions. In the past both the 2 amp versions have died and been repaired by Bose, currently I have 1 completely dead 2 amp version and a 3 amp version that appeared to enter a tripping state (all lights flashing) in now has no power light (green) but the phantom power leds (red) light up – any ideas ?

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      • Hello I had my Bose L1 classic repaired the guy replaced all the amplifiers and my unit worked good for one show then at a practice the bottom tower popped loud and is now making a intermittent popping noise out of the bottom tower when I tore down the unit I checked the wires from the amp that go to the control board and the black and white wire that goes to the bottom tower has a spike on my meter is it possible that I have a faulty amplifier from the supplier. Any input will be greatly appreciated

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      • Crossing my fingers on this…
        I have an old Bose L1 Model 1 I Classic PS1 Power Stand that I used to LOVE.
        As you know BOSE is a bitch when you ask about repairs, parts, etc…
        The Power stand is dead and searching the internet I saw your post.
        Is there ANY chance that you are still repairing these?
        I’m in Palm Desert CA
        Please let me know..

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      • One thing I did for someone who was local to SF Bay Area, was swap one my working L2 bases for their dead one for $400. Then when I get time, inclination, and ambition, I fix the dead one. This way I and they don’t have to worry about success or failure and it doesn’t feel like a “job”. If you are interested, comment here with your email address and I will NOT approve it so it won’t be made public. Then I will contact you directly.

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  6. Hello
    I am so ticked with Bose that had written a scathing letter telling them to just ship their work overseas and have it done in sweatshops because that’s all it’s worth to me now! That obviously got me nowhere and I never got a response from “customer service”. Your site has been the first one I have seen that deals with this problem and actually has a resolve. I too am victim to the “it just won’t turn on any more and the fuse doesn’t work. Sounds like this could be a very lucrative business. I too am wondering if you will repair my L1 as I am not an electronics savvy individual. I hope to hear from you.

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    • Hi. I’d be happy to try fixing peoples towers, but the problem is that I can’t guarantee success (I’m an EE, but not a pro service tech) and shipping would be prohibitive. I also wouldn’t know what to charge because it takes hours to carefully open up the unit. If you live within driving distance of 94022 or can stomach paying two way shipping, I’d be willing to try, and not charge unless I succeeded.

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  7. I have a Bose L1 Classic
    A guy brought to me.
    I have checked the power amp direct Inputs on the PS1 they all work.
    The input channels seem to be receiving signal fine.
    But are not outputting to the power amps.
    Channnel inserts output.
    Have you run into this issue? The guy said he pluged in Speakers to the power amp outs when the tower was pluged in. Why I don’t know.
    It clearly says not to. To contact me

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    • Sorry, no. The Aux Power Supply issue is the only thing I have dealt with. I have a link to the schematics. The only thing I can suggest is to plod through the blocks step by step to see where the signal stops.

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  8. By looking at the pictures of the aux ps board, it looks like you swapped out MOSFET Q601 and thermistor TH603. Is that correct? If so, what did you use for the thermistor. The only 100C lug type I’ve found is a muRata and Mouser says it’s obsolete. Any help would be appreciated.

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    • I may have pulled those components during my “shotgun” troubleshooting efforts, but I did not replace them. They are the originals. Are you sure they are bad? They should be pretty easy to test.

      Looking at the photo now, None of the diodes show rework, but I am sure that I replaced one. The Aux Power Supply photo might have been taken before I did that. I’m not sure now which diode I replaced, but it was one of large ones (sorry for not being more precise). The labels for three large diodes are visible (D605, D608, and D609). The labels for the other two (near R630 and R631) are not visible in the picture. I would check these 5 diodes first.

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      • Yeah, I haven’t tested the mosfet and the thermistor. I just wanted to make sure I can get the parts. The diodes are no problem. I can get those for $.55/ea. Thanks.

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  9. I just finished a repair on the aux supply. In my case, it was D602 and D607. Also, you’re absolutely correct that the supply will not output correct voltages unless it’s connected to the load(s).

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  10. My L1 has not been used for 2 years (will not power up). Tried to find someone in northwest NJ that could repair (besides Bose) but no one had a schematic. Does anyone know who can do the repair in the NJ area?

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  11. GeorgeU. I do not know yet of a place in NJ for you, but there is a place in GA, and a place in CA that I took my two units to. The guy’s repair time is about 2 days, but shipping might be prohibitive for you. Also, he is not cheap. About $400 for the repair, but you get a warranty. He dd tell me that the Classic L1 was better built than later models. If you have the Classic with no power up, chances are 1 of the amps blew and that blew the Aux Power Supply. The main Power Supply is probably okay, but 1 or more amps went out and took out the Aux unit. The Classic is an easier diagnosis and fix than the Model 1. You might be able to find a shop in your area for the repair if you have the Classic L1. The Model 1 combines the amps and the power supplies, making dianosis harder and time consuming.

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    • I would like the information on the repair guy in California. I have 4 L1’s, 3 of which are not powering up. As everyone has stated, Bose only wants to sell the new model 2. I’m in California and maybe I can get mine repaired.

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    • Hi. Have a 14 year old PS1. Been flawless until a mont ago. Just has no power anymore. It would be worth fixing as Bose’s option is to buy a new system… I live in Chattanooga, TN on North border of GA. Could you send me guy’s name who does repair? Thanks in advance. -JIm

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  12. Guess I should have used spell check. Sorry for the misspellings. O.C. Electronic Repair is the place I go to in Southern California. Modular Electronics in Roswell Georgia is the other place.

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  13. Lens42, Thanks for all the information. Very much. Mistakenly leaving my unit on overnight was the last thing I did with it. Now nothing. Power is a bit dirty around here. I’ve taken the unit apart (Note to others: there’s a couple sneaky screws and a ground screw that will impede taking the power supply cabinet out – you’ll find them.). Can I send you the PCB(s) for testing? Glad to pay, success or otherwise. Drop me a line and I’ll fill you in.

    Thanks again – really nice work here.
    Andy Quinn

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    • My base on an L1 Model 1 blew up. I could not repair it but I saved the column radiator, I mounted each section on poles and fed them with a Crown 1000 amp in stereo. Incredible sound.

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      • Hi CharlyV, could you send me the info on wiring up the column radiator to the Crown. I have a QSC 1000 watt and should work like the Crown. Thanks in advance. Tim

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      • Hi, I too would like to know exactly what you did.
        I cant find the schems for the L1 columns but I have everything else.
        Thanks

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  14. Hi All,

    I have successfully repaired a number of these now, always diode issues, the last unit I have bought faulty has had a repair attempt already and the aux PSU is missing the EC-28 flyback transformer !!!, would anyone here want to sell me a faulty AUX PSU if you have any units you have been unable to repair ?, you could list it on Ebay and id buy it that way,

    Many thanks, look forward to responses.

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  15. If it’s any help to anyone (and while I have no connection this company other than as a very satisfied customer) I would highly recommend https://entertainmenthouse.co.uk/. I was told by Bose that my L1 Model 1 unit (which completely died) was unrepairable. I couriered it from Scotland to the company in Buckinghamshire, where a gentleman called Clive fixed it up so that it now works perfectly.

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  16. Hi! i also have a faulty PSU. D607 was short circuited, i replaced it and now i get some voltage on the secondary side, but very low. like 1V on most of the rails. I checked all other diodes (I trippled checked D202) and they all test fine. also de MOSFET is OK.
    If i test the aux board only connected to the High voltage DC rail comming from EMI Board, and nothing else connected to it, i should get voltages on the output connector going to preamp section right? they should be higher than expected and not as low, right? i tried to connect all boards, and the only thing i see is the phamtom power led comming up but intermitently. power led doesn’t turn on. I’m also assuming that i don’t need to have the speaker connected, right?
    thanks guy for any available help. (i also replaced all electrolytic caps)

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    • *i meant i tripple checked D602, it is fine. I’m probably just going to replace the PWM IC and check the feedback network for any faults..

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    • Yes, JohnD. When I first activated the board after replacing the diode, the output voltages were all pretty odd. I can’t recall if they were higher or lower than expected, but 1V on the rails does not seem right. My test was with no loads on the Aux supply. Only the EMI board and Aux power board were powered during the preliminary test. The voltages then all fell into line when amplifier loads were connected.

      Thinking about it, it seems logical that many outputs would be low if no loads are connected. IIRC, the circuit drives a transformer with multiple output taps. One output is fed back, so if there is no load on that output, the circuit will only need to switch infrequently to satisfy the fed-back output. That infrequent switching will not generate much voltage on the other “slave” outputs, so they may read very low. The fed-back output however (I think is was +15V) should read above or near the correct voltage. IIRC, I think that one read high and pulsed above 15V, because it had no load to discharge its capacitors.

      You should be able to verify operation of the PWM chip without pulling it (but maybe swapping is easier). Chips like this have a reference and feedback input. If the feedback input is below the reference input and the chip is not switching, then the chip is at fault. But if the chip it switching and nothing is happening at the transformer primary, then something else is wrong (maybe the power MOSFET). If the regulated output is low, but the feedback input to the PWM is “lying” and fooling it into thinking the output is in regulation (causing it not to switch), then something in the feedback path is bad. A big warning re checking the PWM is that parts of the circuit are hot to the AC power line, so the EMI board needs to be powered from an isolation transformer before you can safely probe these circuits. From the sound of your comments. it appears you are likely familiar with un-isolated AC risks. If not, get some technical guidance before proceeding.

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      • For god sake, the L1 in NOT AC at the boards, please be careful guys your dealing with 450v DC after the EMI filters, this is deadly

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    • Hi all, I’m new, I have the exact same problem, D607 in short, substitute but still presents the problem, led Phamtom Flicker Red, also replaced K2645 and UC2843B. Did you solve the problem and how? Thanks, if you want you can also answer me by mail (mb.ortu@tiscali.it)

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  17. This is such an authentic expression of the phrase “it takes a village” I love this. I have 2 L1 bases needing repair. Please contact me to discuss an agreement and shipping. Rich in Coronado, CA

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  18. I have a similar issue. No poer on the L1. I followed the advice and did find a bad diode which I replaced. The system still does not power up, however. Anything else come to mind? I saw no bad components or bloated capacitors on any of the boards. NO signs of burn’t components.

    BTW I had to order the diodes from China and buy a 10 lot so if anyone needs the elusive IR043IL 31DQIO DIODE I have a few left over.

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  19. RE: Amp “Replacement” / lens42
    “This is a great idea as a last resort, but you do lose a big L1 feature, which is the DSP magic that allows you the place the towers BEHIND the performers without generating feedback.”

    But I always thought the “Magic”/ Feedback rejection came from the “Line Array” design of the speaker column more than the “DPS” portion of the amp??

    I’m “just a puppy” here – but have been using the L1 (Original) for over ten years each week in Worship and we have acquired a newer / older L1 that just started giving us an issue that brought me here today…..

    We set up the 2 L1’s in a relatively small room 70’ x 50’ – one unit on each side of the (center) screen – 2 B1’s on each L1.

    Last week I noticed a “POP” early on before the service, and later noticed one of the B1’s may not have been putting out as I was playing bass – however I didn’t look into the issue at that time.

    This Sunday during rehearsal I bent down to hear the nearby B1, no sound, went and listened to the other, no sound….. swapped some speakon cables, still no sound. THEN I actually put the bass down & “listened” and noticed that the column was not putting out either… I looked at the L1 panel to see input lights 1 & 2 RED – (we were only feeding input 1) – Power LED was lit Green. – Powered on-off a few times – same result, no sound, same LED’s lit.- We continued the service using only the one unit. – Which actually works just fine, but not a “balanced;” in the room.

    Reading here that BOSE no longer wishes to service these units???? It may just be best to set up our own amp to feed the column & subs, granted it may take a while to set the EQ’s to match the other side of the room (Original L1) – but we’re not pushing much sound (volume wise) – Just looking for a balanced sound throughout the room. – Then again, perhaps “forget” both (cumbersome) base/amp modules and use the columns and B1’s

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  20. Hello I would like you to help me with my problem, I have an L1 II, and it does not sound. the power LED turns red … can you help me?

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  21. Hi everybody, I have the same problem, I changed the D607, was in short, but I don’t have any voltage, I think the pwm is not working.

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  22. I have Bose L1 model 1 and classic for sell I have to sets of speakers and bass. one of the psu does not work but the other one works but the top tower speaker does not work. I am selling everything as is. the speakers are in cases

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    • My phone number is 614-372-9792 if you are interested in buying the Bose L1 model 1 and classic that I posted above.

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    • I have 2 Bose L1 units. Both have the same power problem. My tech has replaced the the diode on the aux power with no luck. Has anyone thought of implanting a small amp into that space to power the board and speakers either internally or externally?
      Has anyone experimented in that direction? Rich

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      • I had the same problem (top speaker not working). The problem was actually the connection at the top of the BOTTOM speaker, which over time gets repeatedly pounded when the top speaker is rammed home. So have a look at that connection. In my case it was fixed relatively easily with the aid of some Gorrilla glue and by fiddling with the wires. Regarding the base unit, as you’ve probably discovered Bose no longer support the older L1s, and they’ll tell you to trash it. But if you find the right guy it can be repaired. (I’m in the UK, where there is a genius who bought a load of parts from Bose and can fix anything.) Best of luck.

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  23. Hello everyone here,

    I am a pro technician in Belgium/ Antwerp. My adress is given by Bose Belgium/Europe to customers of the L1 type 1 (old version) with problems, because they are not given support on this product anymore. You can reach me at luc@techniekvoormuziek.be. I am using a fixed repair price, (sending back-price excluded).
    Yours sincerely,
    Luc Bertels/Beta repair
    Techniek voor muziek

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  24. I AM LOOKING FOR THE TOP CONNECTOR FOR THE LOWER LINE ARRAY OF AN L1. IT WAS PUSHED IN AFTER A GIG. DOES ANYONE KNOW WHERE TO PURCHASE THIS PIECE. THANKS ROGER

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    • The exact same thing happened to me (I had omitted to tell my band mate this was a speaker not a scaffolding poll). I was unable to source the part (Bose are no help) but my regular technician managed to reconstruct it using strong glue. I’ve been careful with it over the last 2 years, but it has worked OK.

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  25. Hello,

    My unit has failed as well.. surprise surprise. I’m in San Diego and am looking for a reputable local shop with experience on this unit? Anyone?

    Also, I might have the chance to buy a working bottom unit. If I bought that, are there instructions on what parts to replace prophylactically? Only the diodes on the power supply?

    Thanks,

    Dave

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    • Dave I live in San Diego and have 2 PAs with the power problem. I’ve had one unit at Top Gear who are great but have not been able to get the system running. Maybe we could chat and get a plan in place
      Rich. Healedcancer@gmail.com

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  26. Hello,

    I tried having my unit fixed by a stereo repair shop in SD. He returned the unit after he replaced a diode in the control board and an out of tolerance 4007 diode. the unit worked at the shop. I brought the unit home and connected it to my mixer. It worked for a couple minutes and then went dead. I took it back to the shop and it worked. He was running a single channel into the amp. I brought it back to my location and it stopped working again, minutes after I hooked it up. By the way, my inputs to the L1 had been working fine for years and I could plug those inputs into other PA systems and everything works fine so it’s not the inputs. Also, I drive the units at a very low level, maybe 1 on a scale of 1-10.

    Anyway, I even took my whole setup, mixer, bass, etc. back to the shop and damn if it didn’t work at his location again. I’m suspecting an out of spec component from the initial failure is flakey and intermittent and I’m unlucky that it didn’t happen at the shop. So, again I brought the equipment back to my location and started playing. After about 5 minutes of playing there was a LOUD POP indicating a short or significant electronic failure. After that pop we were back at the beginning where there is no power to the unit.

    I returned the unit again to the shop and he replaced all the diodes in the power supply. The PS worked but then he indicated the 15V rail was being pulled down by the digital section of the unit. He was unable to diagnose that failure and retuned the not working unit to me.

    Do any of the electronics experts on this thread have any comment/advice on where to go from here? I’m in San Diego.

    There were some comments on just using the tower as a speaker. My gut feel is that won’t sound good since Bose has a lot of DSP code shaping the sound coming out of the tower.

    My final option would be to sell the unit for parts…

    Thanks,

    Dave

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    • This is tough. The root is probably just a loose connection or solder joint, but it SO time consuming to even get inside, that any repair is prohibitive if you are paying some one to fix it. I have two units I no longer use, so for one unfortunate owner, I traded one of my good bases for his dead one plus $350. When I get really bored, I’ll try to fix the dead one. He was local enough that we didn’t have to ship (I expect shipping costs would make the transaction a bad deal). If you want to do the same deal for my 2nd good base, let me know. I’m in SF Bay area.

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      • What do you think about the 15V rail being pulled down by the digital section of the unit? Have you experienced that?

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      • I’ll think about the swap out offer. Maybe next time I drive up N. Can you PM your contact info?

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      • Hi, I am located on the SF peninsula and just had my L1 unit fail yesterday. What seems a bit different than the issues I am reading about here is my unit has power but the tower stopped working yet still getting sound out of the base speaker. There was a brief popping sound out of the tower followed by electrical burn coming out of the base power unit. I’d be interested talking to you about buying one of your working units. Please let me know. Thanks.

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      • Hi Trevor – Unfortunately, I just swapped out my only remaining working L1 for a dead one plus cash. If one speaker is still working, that’s encouraging – maybe a blown capacitor in the amp that drives the tower. I will contact you privately.

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    • Dave make sure your plug is wired correctly. Also I asked the repair person if he could bypass the amplifier and put in a plug and play amp unit. Haven’t heard back.

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      • Thanks Rich,

        The tech did suggest a noisy 120V outlet and I did verify the correct wiring of that outlet as well. It’s the same on that the unit was working fine with for the last 5 years…

        Let me know what you figure out w/ the amp bypass approach.

        Thanks,

        – Dave

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  27. Can anyone email me a copy of the schematics for the L1 Model 1 columns and bass unit? I have a guy locally with no base and he has a column and a bass unit. I can see if my tech can hardwire them to run off an amp/xover setup directly?
    Thanks!
    dan@vvxlive.com

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    • I’m on the peninsula. As I mentioned to a few others, l’ll trade a working L1 base for a dead one plus $400. If interested, reply to this comment with your email and I won’t approve the comment so your address won’t be public. Then I’ll reply to you.

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  28. I have a BOSE PS1 L1 that went down hill. It started with intermittent popping and crackling then a low warble. The Red light is orange. It used to be green. Could this be an indicator of power stability?

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    • I repaired the auxillary power supply by replacing the D601, D605, D606, D607, D608, D609, Q601.
      I get power, the signal indicator light on the remote shows activity but no sound coming through.
      The next step is the 27v control circuitry check. If the logic boards are no good then end game.
      I’ll strip out the DSP board, hot wire the control lines in the aux board to allow power through the +27ps boards and see if that part of the system still produces sound. I believe the radiator, the amps and the ps boards are good.
      If my attempts dont work I have a really great sound bar.

      Like

  29. I have 2 L1 model 1 bases with suspected AUX power supply issues. It took about 2 hours to get the Aux power supply circuit out, but It’s now out. Anyone in the Dallas / Ft Worth Texas area with broken units ? The entire plastic cabinet of my 2nd unit is busted up, so may end up with all internal parts of it available. I plan to take the Aux PS out of unit 2 and swap it to see if that makes unit 1 work, then start chasing diodes on both units until I get them fixed. I also have an extra set of top/bottom towers but the center connector on one and the bottom of the other is cracked / broken so I will be chasing down those parts. They will be extra also. marktrezz – yahoo – com

    Like

    • Hi Mark – If you want to send me your aux ps modules, I should be able to fix them for not too much $, If you want to part out one, I need an aux ps for a tower I have. I will contact you via your web site.

      Like

  30. I need help with a Bose L1 Model 1, when I turn it on the LED changes from green to amber, I have no audio in both towers but I have on the B1 Bass module. Not sure where to start on that… I am near to San Diego area.

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      • Hi, Lens

        My L1 seems to have to opposite problem as Omar.
        Sound in the towers but the B1s are dead. Amber powerlight.
        Do you have any ideas?

        Live in Sweden, but maybe i can get someone over here to do the job…

        Is 2022 the year for the L1s to give up?

        Thanks.

        Like

      • There are separate power supply boards that generate +/-28V for each power amp module. I had one unit where the power supply for one amp was dead, consequently that amp would not work. In my case that was for the lower tower, but it could just as likely been for the base output. An easy test if you get it open is to check for the +/-28V getting to the base power amp.

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  31. Hi Omar. Not sure if this will help, but I had the same issue with one of my 2 (old) L1 units. The amber light showed and there was no sound. I found (totally by accident – I have no technical skills) that if you FIRST turn up the volume to say 33%, and THEN power up the unit, it works fine. You may care to try this simple step before embarking on anything more expensive, and I hope it works. Best regards.

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  32. I have a Bose PS1 and it makes a hum/screeching noise on the lower speaker only. Upon taking it apart, the Aux power supply is making a ticking noise and fluctuates the voltage with the ticking noise. Any suggestions? If you are interested I could, send it to you for repair. I am pretty good with electronics, so any suggestions would be helpful.

    Like

    • Hi Josh – This a bit odd. If the upper speaker works, and you have a green power LED, that would usually indicate the aux power supply is OK, but from what you say about the fluctuating aux supply outputs, it sounds like it is not OK. The first thing I would try is to isolate the problem. If you disconnect power to the lower speaker amplifier, does the aux board still click? You may have two unrelated issues. If you are comfortable doing board level troubleshooting on the aux board, I would first check all the diodes. One or more of the big Schottky diodes can go bad and very often the bootstrap diode (D602) also goes bad. As do a careful visual inspection because I sometimes will see darkened stressed resistors, indicating other issues. Surprisingly, I have yet to find a bad capacitor (which is what most “shade tree mechanics” usually blame). If you don’t want to tackle board level repair, I can do a board repair (or swap if it takes me too long to fix yours) for $200.

      Like

  33. Hi, I live northwest of Chicago; and own two L1 M1 (second gen) that push double B1s. My son just informed me one of the amps won’t power up after running for about an hour in an older facility. After coaching him through the usual connection troubleshooting, my inclination is a blown fuse; but, after reading through multiple posts here, the symptoms indicate it could also be the power supply has failed due to poor voltage in the facility he’s at. As I don’t have my hands on the unit nor any EE expertise, I thought I’d start with looking for replacement fuses.

    Bose L1M1 specs say, “T15AH / 250 V”; and an old Chuck-at-Bose post says, “It’s a T15A, 125V/250V, 6.3x32mm (slo-blow)” which Bose doesn’t carry anymore; and I’ve had no success locating them. Can anyone share recent success purchasing these specific fuses at a specific online or retail store?

    Thank you!

    Like

  34. My unit just died, I’m going to open it up and look. I know enough to be dangerous, but I tend to get things to work. All the inputs seem to work. The power light comes on green and with in a second turns amber. Any ideas? Thanks/

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  35. hello I am struggling with the repair of my Bose PS1 Power Supply Repair where the first intervention was in the replacement of the resistance R621which was open in addition was replaced IC601 (UC2843AN) with an equivalent one (UC3843B) and the mosfet Q601 (P10NK60ZFP).
    At the ignition I do not find any voltage on CN623 I thought of disconnecting all the other cards from the power supply leaving only the power supply thinking that there was a high load due to some other failure but it was not so I find myself with thousandths of a volt output.
    finally I noticed that leaving everything connected power button in ON and phantom power button (+24) activated the red led lights up a little while the power led is off.
    I hope in your answer cordial greetings

    Like

    • Hello. I can’t look at the schematic right now but one quick comment is that the most common failures I have seen are diodes. Check ALL diodes in circuit with a DMM in diodes test mode. The Schottkys read around 0.25 to 0.3 and the silicon diodes read around 0.45 in the forward direction. Bad ones will read like a near short or open.

      When testing, power the aux board up with all the loads disconnected. If working, the voltages will not read exactly right with no load, but should be within a few volts of the expected value.

      Liked by 1 person

  36. Hi to start thanks for replying
    I tested all the diodes that are in the circuit and found the diode D604 (UF4006) at a loss and the D609 with a measurement of 0.13 while the others are all normal

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  37. hello I just finished the repair and the power supply is back to work as well as other things, I just wanted to know if the cooling fans are activated when a certain temperature is read or are activated when switched on through the power on / off button

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  38. Hello – I was wondering if the Bose L1 array (first gen) can be powered by the Bose PowerShare PS602 power amplifier or similar? Thx! Mark

    Like

  39. i have four L1 model 1 towers that seem to have the same problem. i can remove the AUX power supply boards and bring them to you at your earliest convenience, any help is greatly appreciated. i live in the bay area. if you need more info i can give you my phone number in a private message . thank you for your time!

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      • Hello, I have a 1st generation L1 that seems to have the same issue with the light turning green when turned on and then turning to amber. I live in Oakland and would love to find one of these solutions. Thanks, Glen

        Like

      • Hi Glen. I have the same unit. A while ago, I switched it on (with volume at zero) and it appeared totally”dead”. I then turned volume to 30% and tried switching on again. The light then showed amber/red for a few seconds, and then turned the normal green. This now happens every time. Once green, the L1 works fine. Obviously something is at least slightly wrong with the unit, and I am prepared for it to fail one day (we always use a second L1, which would get us through a gig on its own if the first one failed). So this is just to suggest that, if it ever won’t switch on, try pushing up the volume to say 30% and then switch on again. Best of luck. I think this is simply Bose’s way of persuading us to buy new stuff! 😊

        Like

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