Marshall Stanmore Repair

[Hkekkonen]

My Stanmore is powerless again. Have found some major issues in it. Will share the info later.


Came across with this post on another forum. (mikrocontroller.net/topic/547728)

Translated it from Germany to English.

From Josef Aichhorn (Guest), first contact with my inquiry: 16.12.2022 01:00

Hello everyone!
I want to thank everyone who helped me repair my MARSHALL STANMORE! Yes, it's working again - something I hardly believed after initial research.
The link to Badcaps by "4:46 (Guest)" was very efficient! THANK YOU! Among tons of photos and posts, I found the values and designations of the burned components!
In short, facts (values and designations of the components, see schematic sketch):

2 defective electrolytic capacitors (EKLOs): C59 [electrolyte leakage], C80 [bulging cap], [both 470µ/50V], and as a precaution, 4 more of the same type replaced.
Defective parts: Si 1.6AT, Q7, C124, U1, R18+R104, R19,
Defect due to the removal of the black, hard, tough paste: R69 (not in the power supply: R41[3R30]).
A heartfelt THANK YOU to everyone!
Josef from Austria
PS: As a small thank you, I want to share my painstakingly created sketch of the switching power supply (from Marshall Stanmore) here - because I can imagine that it might be useful ;-) !
Maybe someone can send it to the Badcaps forums - I don't have authorized access yet... just for viewing. °[:->)

And here is the sketch:

[jingleslacks]

Hi Friends,

I'm not too bright, and I could use some guidance. I don't know a lot of part names or terminology, but I'm trying to follow along. I was measuring voltage across my chips, and my cat got curious and a bit too close to the exposed electronics. I turned my head for a second to shoo him away. In that moment, I was met with a tiny pop, flame and smoke from my leads shorting something. I'm pretty sure I fried the chip. I don't know it's sole purpose, but now I'm not getting any real measurable voltage to that board. My (what I think is my BIOS chip) was getting 1.8V- now nothing. I don't remember the voltage of the cooked chip. Any wisdom would be appreciated. If anyone has the file for that chip, it would be double appreciated.

[jingleslacks]

I realised that I just posted my previous in the wrong forum since I have a Stanmore II. In other news, I found these in another group. Hope they help

[Dioniso]

Hello everyone, I had an update issue installing the last firmware version on my Stanmore II. Actually I'm able to power on the speaker but control panel seems freeze.
It is also possible to soft reset the speaker and to connect the smartphone to the device but after few seconds panel get freeze again.
s anyone aware how to hard reset the software? I saw that we have a service port on the back, it is usefull for the scope?

[Puuhis79]

I have one on my desk to get scrapped or fixed😂
I managed to measure those zeners (zd1 and zd3), feedback opto is not working so it needs to be replaced. Also a handfull of other componens has toasted😂

all caps seems to be in working condition

ZD1 = 6v
ZD3 = 17.7v

[brockauly]

Hi,

My TAS5342A is completely burned. Thank you for the chip's identification.
I see on providers webistes that there exist a variant of that chip (TAS5342LA), which is available while the original is not.

Does anyone know if I can safely replace the TAS5342A with a TAS5342LA ? Will it work properly ?

[gergogergo]

Hi,

Marshall Stanmore 1st gen. sounds nice and well at quarter volume, but turns off at higher volumes.

What could be wrong? Thank you for your help.

[Hkekkonen]

Hi,

Marshall Stanmore 1st gen. sounds nice and well at quarter volume, but turns off at higher volumes.

What could be wrong? Thank you for your help.

Im not an expert on electronics but here comes what i found out.

Look for left over solder balls on the pcp board. Mine had alot of them they might make short at higher operating current/ higher volume or if they move and cause short.
Main board was bent because of the insulation in between the back plate and board was too high. That causes stress on it and it being inside the speaker vibrating probaly wont do anything good in a long run.
There was short on ribbon cable connector between two pins on the one that connects the mainboard to frontpanel(pcp with buttons/knobs) i have no idea did it cause problems or not. Did some of the other repairs as well without testing it in between.

Replaced 3 pcs of caps near optocoupler and 1-2 other ones.

I got the speaker working after cleaning out those solder balls and sorting out the other issues.

Only after couple hours of playing some music it would shut down again. I replaced caps near optocoupler and it would work for couple more hours and went silent again. And last i accidently shorted the board and burnt the optocoupler and some other components around it and thats when i gave up on it.

I did buy another speaker as used to see if it has these same factory made faults/issues. Well it doesent. Same look and model but different product number on it and slightly different circuit. Has way worse sound dont know if it was like that since it had been new.

Then i changed some messages with Marshall(Marshall headphones) and adressed some of these issues as factory fault and demanded for compensation. They only offered me almost worthless gift card if i would send them detailed info of all the issues and would have them fix my speaker with me having to pay for the job. No deal they can f**k off!

Did some reviewing on new models. They definetly havent made their products any better and dont seem to care to do so on next gen. Just dont anyone buy these they are complete cheap ass junk. I also found out that these products are only licensed to use Marshall's brand but they are not even authentic Marshall products and not made or designed by Marshall. Thats so idiotic and only does harm to their reputation in my opinion its ridiculous. Brand is actually Marshall headphones and doesent have anything else do with real Marshall than the brand. Thats what i was told and i see this as💩 product line that they just dont want to take responsibility of and its way of selling cheap short lived products to consumers.

[Jose Luis Gil]

Hi guys, I just fell upon this post while searching information about the Stanmore...
A friend (now not so sure!) gave me his speaker and I've been trying to repair it. Apparently everything is working, besides the big capacitor from the power side (done!), and the U15, which is completely burnt.
I removed it with the purpose of replace it, but I've noticed that part of the tracks are broken because of the U15 burn.
Does anyone have a clear picture of the board with the U15 removed, to see if I can try to rebuild the burnt part? It will be the last try I'll make with this speaker, as I've read that a lot of people have had issues with...

Thanks a lot in advance to everybody!!