Marshall Stanmore Repair

[hann]

Re: Marshall Stanmore Repair

Hi Hann,
I've read your post with great interest.
My Stanmore is also down, no led on at all, just earing a little click, for a few seconds, at the start.
No success after replacing the MC34063A, the LM317T and FMG23S.
So I would like to make your solution (replacing the 3.3/50), but I don't see it on the PCB...
Could you please give me its place and its reference ?
Thanks a lot.
Best regards.
Michel (from France).

pls see attached

[hann]

Re: Marshall Stanmore Repair

Hi Hann,
I've read your post with great interest.
My Stanmore is also down, no led on at all, just earing a little click, for a few seconds, at the start.
No success after replacing the MC34063A, the LM317T and FMG23S.
So I would like to make your solution (replacing the 3.3/50), but I don't see it on the PCB...
Could you please give me its place and its reference ?
Thanks a lot.
Best regards.
Michel (from France).

pla see my drawn schem its near OB2269

[Tamaska]

Re: Marshall Stanmore Repair

Hi Guys,

I have just joined this forum to be able to talk to you.
My stanmore is not powering up either.
Basically what happened:I unplugged it from the socket while it was playing, and ever since there's no pilot light and power.
I found the fuse blown so i replaced this, this gave not a lot of joy. While i was clapping happily for the fact the pilot light came up by the time i clapped twice it went out again.
I took out the big board and looked for damaged components but found nothing yet.
I did some measurements around the diodes to make sure they are not blown they seem alright. Now the speaker is just eating fuses. It looks like a dead short but i cant find the short.

Do you have any idea what it could be? What should i look for?

[walzz]

Re: Marshall Stanmore Repair

Update:
The amplifier IC has the marking 42TTI A87CG4 (?) but someone else suggests that it could be a TAS5342A IC?

Has anyone information what the amplifier IC could be?

As mentioned earlier in this thread U15 is a Texas Instruments TAS5342A (100w Class D amplifier with digital input) in a 44pin HTSSOP package.

Data sheet: http://www.ti.com/lit/ds/symlink/tas5342a.pdf

[walzz]

Re: Marshall Stanmore Repair

I'm still looking for a schematic/ service manual for this amp. Hope someone can help with a copy or a link?

Posts in other repair forums mention the use of cheap chinese 'ChenX' caps on this board that leak electrolyte. Caps with Marshall goop poured around them had corrosion hiding underneath which destroyed a number of SMT components. I believe some of these design issues were addressed in the Mk2 version.

[Chris_J]

Re: Marshall Stanmore Repair

Update:
The power amplifier was fried and the 7812 IC together withthe shorted D7 located underneath. Everything replaced except the amplifier.

The unit started up and this time the bluetooth worked as well Could easy pair it so there is hope for the unit but we see when I receive the power amplifier.

The amplifier IC has the marking 42TTI A87CG4 (?) but someone else suggests that it could be a TAS5342A IC?

Has anyone information what the amplifier IC could be?

[Chris_J]

Re: Marshall Stanmore Repair

Hi,

Interesting thread. I have replaced the burned R23 (220 ohm) with a bigger resistor underneath the PCB. I have attached a picture so you can see how I have done it.

I have also a picture for you who have problems finding the 3.3 uF capacitor.

PS still broken but faultfinding is still in progress.

[VanDivX]

Re: Marshall Stanmore Repair

I have already sent the speaker to the authorized Marshall repair shop out of province for $35 CAD to get it fixed.

I wonder if you are still around, if you could report how the repair went. I am in Toronto and guess 'out of province' likely meant to Quebec, Montreal?

I took several months off trying to fix mine, maybe will give it another go since in the meantime I got some parts for it I ordered from China. My speaker blows fuse and I hope it is something wrong with P/S part of the PCB, like the bridge diode or the MOSFET

[pbakai182]

Re: Marshall Stanmore Repair

Hi all,

So I received the replacement IC chip (MC34063API) and after a long and arduous effort to solder this larger thru hole component onto a surface mount board, the original intermittent bluetooth problem persisted...

I have already sent the speaker to the authorized Marshall repair shop out of province for $35 CAD to get it fixed.
Hopefully they don't have an issue with the fact that I have a jumper wire from one of the IC pins to the connecting smd capacitor as the damn pin track came off as soon as I touched it with my solder wick

[benzbenz]

Re: Marshall Stanmore Repair

hi everyone
i am new to fix my Stanmore
my Stanmore while playing music , sound went on and off all the time
with some strange noise before went off.
anyone know how to fix it?
appreciated

[pukipuki09]

Re: Marshall Stanmore Repair

sir R_J thanks for the input sir. i have found the fault. its the 3.3/50 volts e cap, replaced it then voila! power restored. i studied the datasheet on the pwm ic. the e cap doesn't charge that is why the ic wont start. a very big thank to you sir.

Hi,
I just got this device from my friend for repair.
Where this 3.3/50 cap is located on PCB?

[pbakai182]

Re: Marshall Stanmore Repair

Also, if anyone has had success swapping out the 8-pin surface mount DIP MC34063A who was experiencing my issues (Case#1, Bluetooth connecting but no sound), I would be very grateful if you could try to guide me in how to check the voltage on the part, and anything I need to be aware of when replacing. I have a basic multimeter, and an OK soldering iron kit. My experience is beginner in the electronics field, I've successfully swapped out a damaged micro USB port on a Logitech Bluetooth speaker, so I have confidence in my soldering abilities.

[pbakai182]

Re: Marshall Stanmore Repair

Hello, I purchased a used Stanmore (1st edition) and while the unit turns on, LEDs working, Bluetooth connecting and staying a solid red LED, the sound will turn off when switching media apps (playing music, then playing a YouTube video, then back to music). The issue is very odd, as sometimes when I unpair and re-connect to Bluetooth, music will play, and sometimes it won't at all no matter how many times I try to unpair, unplug, and reconnect...

Speaker works just fine when connected to AUX... I have been able to replicate these no-sound issues with BT over 3 phones in total (Galaxy S7, A50, and iPhone 6S).

Marshall is willing to repair the issue (non-warranty repair), having me pay for shipping. But if I can repair by swapping out a 10 cent part, then I would prefer to try that. However, I'm not sure if Marshall would still repair if I opened up the back...

So has anyone here experienced my issues with speaker working fine with other inputs except no sound on Bluetooth even though it is connecting successfully?

Thanks.

[michel91]

Re: Marshall Stanmore Repair

Hi Hann,
I've read your post with great interest.
My Stanmore is also down, no led on at all, just earing a little click, for a few seconds, at the start.
No success after replacing the MC34063A, the LM317T and FMG23S.
So I would like to make your solution (replacing the 3.3/50), but I don't see it on the PCB...
Could you please give me its place and its reference ?
Thanks a lot.
Best regards.
Michel (from France).

[Andersswe]

Re: Marshall Stanmore Repair

Im trying to repair my Marshall now, and i see that c9 is burnt, what part is that?

[jabase]

Re: Marshall Stanmore Repair

Greetings...I was looking around for a schematic for the Stanmore and came across your discussion. I should pop in more often . I usually park my brain in some other forums :-)
Anyway ,the unit I received for service did not have audio. Unit came on with LED ,etc. I found that U15, audio output IC was cooked. I replace the IC, however I still have no sound. All voltages appear to be good. I can see audio at U19 (in/outs) . I see audio going into U4, but nothing coming out, data or analog. There could be a micro/software issue not enabling this IC, or something else. Seeing how U15 imploded pretty good, I suspect that it may taken out something else. Man , a schematic or even a block diagram would be great right now. It's fairly easy to obtain and replace U4 , which I'll do , but looking for other suggestions ...Thanks !!!

For reference:
U15 : TAS5342A(digikey)
U4: PCM1808 ( digikey)

U19 : HCF4052

[RethoricalCheese]

Re: Marshall Stanmore Repair

Put a lightbulb in series before powering up.

[VanDivX]

Re: Marshall Stanmore Repair

Does anybody know what is the purpose of the NPN transistor in hot side next to the optocoupler, marked in red square?

Just a guess - the OP mentions in 'case' #3 'blown fuse' some ""standby mode" circuitry thrown in for European compliance"

3. If a surge occurred and replacing the fuse doesn't solve the problem, this could be a fault of the primary (power supply) or secondary (cold) side of the PCB. ...The power supply is a 100-240V SMPS with some "standby mode" circuitry thrown in for European compliance.

Could someone have removed that transistor in some earlier 'repair effort'? It might well be superfluous but then again... again just guessing, maybe someone removed it, found it faulty but didn't get replacement and abandoned working on it?

As for my problem, I wait for the mosfet and rectifying bridge to arrive in mail but replacing them is just a shot in dark.
I think the big clue for fuse blowing might be my measuring 'open circuit' on A/C 120V input when there is no power supplied - yet once AC is connected, the fuse blows, indicating short circuit.

[RethoricalCheese]

Re: Marshall Stanmore Repair

Does anybody know what is the purpose of the NPN transistor in hot side next to the optocoupler, marked in red square?

I've got a speaker which has it missing. I have ordered a new one but I doubt it fixes the issue I have.

It does power on but no sounds coming from any input.

[VanDivX]

Re: Marshall Stanmore Repair

Can one edit one's posts here? Like at least to correct some spelling? I don't see how to do that.

Anyway, I measured across the two yellow blocks either side of the smaller transformer and they measure 0.8uF, I suppose then they are capacitors then and are OK. One of them is marked as CX1 on pcb.

I tried to take picture of the markings on the 'transistor' mounted on the black heatsing right behind that big capacitor I removed for measuring and it says 'F' 1FO5BR FDPF 10N60NZ

Googling around, I found it is FDPF10N60NZ ECAD Model
Fairchild Semiconductor MOSFET N-CH 600V 10A TO-220F

MOSFET is another possible culprit - all I know is it sensitive to electrostatic discharge and it passes current depending on input... that might be why I don't measure short on AC input, it needs powered up to short it (if it is faulty). I just don't know how to check it, if someone has an advice how to measure on it, I'd be grateful. Keep in mind I can't power the pcb up to measure voltages on it.