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Author Topic: Marshall DSL201 OT Possibly Blown  (Read 14249 times)

g1

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Re: Marshall DSL201 OT Possibly Blown
« Reply #30 on: January 19, 2014, 02:29:37 PM »
Have you checked R71?
Have you resoldered the EL84 sockets?

Littlewyan

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Re: Marshall DSL201 OT Possibly Blown
« Reply #31 on: January 19, 2014, 03:02:03 PM »
No I must admit I havent

Littlewyan

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Re: Marshall DSL201 OT Possibly Blown
« Reply #32 on: January 20, 2014, 03:06:22 PM »
There isn't much point now am afraid to say as my friend took the amp apart last night to check for cold solder joints and when he put it back together he mixed up a red and black lead. Anyway he said something popped and smoke came out the back, fried PT :(. I did tell him to wait for me as he didn't know how to discharge capacitors, i told him he was lucky there was no charge left in them!

joecool85

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Re: Marshall DSL201 OT Possibly Blown
« Reply #33 on: January 21, 2014, 08:04:43 AM »
There isn't much point now am afraid to say as my friend took the amp apart last night to check for cold solder joints and when he put it back together he mixed up a red and black lead. Anyway he said something popped and smoke came out the back, fried PT :(. I did tell him to wait for me as he didn't know how to discharge capacitors, i told him he was lucky there was no charge left in them!

Wow, that's not good.  Glad no one got hurt.
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Roly

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Re: Marshall DSL201 OT Possibly Blown
« Reply #34 on: January 21, 2014, 10:53:14 AM »
Quote from: Littlewyan
fried PT

You sure about that?  It's generally not that easy.

Offer him $5 for it.
If you say theory and practice don't agree you haven't applied enough theory.

Littlewyan

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Re: Marshall DSL201 OT Possibly Blown
« Reply #35 on: January 21, 2014, 12:56:59 PM »
He said the PT looked damaged so I'm guessing thats where the smoke came from, I'll double check for him when I see him. No thanks Roly, that thing is a can of worms!

Roly

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Re: Marshall DSL201 OT Possibly Blown
« Reply #36 on: January 22, 2014, 07:59:37 AM »
Guessing is okay, but facts are better - you're guessing on his guess.  It may be the tranny, or it could be smoke from a burning resistor came out near there.  Does he even know what a "damaged" tranny looks like?  I remain dubious until proven.

Something a tech learns early on is that most people are truly lousy witnesses, particularly when smoke is involved.  I've even had somebody bring me their "valve" amp to fix that turned out to be fully solid-state.   ::)

"...are you sure?"
"Am I ... WHAT?:o   :trouble
If you say theory and practice don't agree you haven't applied enough theory.

Enzo

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Re: Marshall DSL201 OT Possibly Blown
« Reply #37 on: January 22, 2014, 11:37:12 AM »
Agree^^^


Usually, the thing stops working - smoke is even better - then they come up with the one name of an electronic component, and suggest, "It's probably just a (component name here)."


Transformers do fail now and then but they are the LAST thing on a list of potential failures.

Roly

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Re: Marshall DSL201 OT Possibly Blown
« Reply #38 on: January 23, 2014, 04:55:26 AM »
^^^Yup.  :tu:  OT's certainly do fail, particularly if a valve amp is driven without a speaker connected, but even then they hardly ever smoke (which makes them tricky to diagnose).  Power transformers are generally a lot harder to kill.

I'll make a small bet that if you go sniffing (literally) under the chassis you will quickly turn up a burnt resistor, and where that is will give us a strong clue as to what happened.

Can you be more specific about the black/red wires he misconnected?
If you say theory and practice don't agree you haven't applied enough theory.

Littlewyan

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Re: Marshall DSL201 OT Possibly Blown
« Reply #39 on: January 31, 2014, 02:58:01 PM »
Hi guys sorry its been so long, been very busy with a new project. My mate wants to look at the amp himself now so I've basically left him to it, I'm not sure what hes done but I don't think he can get sound out of it anymore, he does however now know how to discharge capacitors!

Roly

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Re: Marshall DSL201 OT Possibly Blown
« Reply #40 on: January 31, 2014, 11:28:32 PM »
I don't think he can get sound out of it anymore, he does however now know how to discharge capacitors!

It's sulking, and it bit him as a dying gesture.  ::)

If you say theory and practice don't agree you haven't applied enough theory.

Littlewyan

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Re: Marshall DSL201 OT Possibly Blown
« Reply #41 on: April 12, 2014, 04:49:19 AM »
Hello everyone! Been a while. I took the amp back off my mate so I could have another look, however I've got to fix an additional mess that he created. Pretty annoyed here. First off, he was getting sparking, this was caused by no solder on the joint of the mains fuse holder, second, hes replaced the rectifier for the heaters with one that doesn't mount to the board so I've got to mount that on the chassis (cant put the old one back as hes broken the tracks) and third he didnt put the nuts back on the pots when testing and this is the amp's only ground points.

A lot of nuts are also now missing, found big blobs of solder on cable cut offs loose underneath the board and the whole thing is covered in cat hair. One is far from impressed!

DrGonz78

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Re: Marshall DSL201 OT Possibly Blown
« Reply #42 on: April 12, 2014, 05:10:33 AM »
Good thing it is back your possession, poor amp! But that's not too bad of work done on the amp.... if the cat was doing the work  :lmao:. Good luck!!
“A person who never made a mistake never tried anything new.” -Albert Einstein

Roly

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Re: Marshall DSL201 OT Possibly Blown
« Reply #43 on: April 12, 2014, 11:35:03 AM »
Quote from: Littlewyan
I've got to fix an additional mess that he created. Pretty annoyed here.

We know just how you feel.    :trouble

Quote from: Littlewyan
the whole thing is covered in cat hair.


If you say theory and practice don't agree you haven't applied enough theory.

Littlewyan

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Re: Marshall DSL201 OT Possibly Blown
« Reply #44 on: April 22, 2014, 03:33:46 PM »
Right, sorry its been a while. Got the Amp powered up, however I had a very low distorted output. Did the battery and neon test on the OT, dead. Checked the Amp with my scope and found the Output was fine until I got to the otherside of the OT. I think my mate fried it when he connected one of the primaries onto the heater supply. So thats the end of that.