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JCM2000 DSL100

Hi,

just put a Marshall JCM2000, DSL100 on the bench.

Looks nice .....

3 output valves installed, 6CA7EH ( Electro-Harmonix, 02/12), only one of which works.

Two, large mirror burn marks on the glass of one of the dead ones, but the OT and rest of amp seem OK.

Pulled all the 6CA7s and checked the bias voltage on pin 5 of all 4 sockets = -43V at max setting.

Played hot air onto the PCB near the octal sockets for about 20 seconds and re-checked.

Pin 5 voltages had dropped to between 28V & 14 V.

Oh shit !!!!!

How did this amp ever survive for this long with such massive PCB leakage ???

The grid feed resistors are all 220kohms too !!!!

Do Marshall actually have spare PCBs for this god awful POS any more ??

What sort of cost delivered to Sydney Australia ?

.... Phil

Reply to
Phil Allison
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"Gareth Magennis"

** Double negatives like that are mind numbing.
** Was that long ago ?

** Now, that is funny.

So * I * have to prove to Marshall that * I * know what I am doing ?????

They have SFA chance of ever proving the reverse.

** Thanks for the offer.

Is there anything special about ordering such a PCB ?

Or is the amp model number and serial number enough ?

... Phil

Reply to
Phil Allison

"Gareth Magennis"

** Thanks again.

I found this page that details the many problems techs have found with these Marshalls.

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Quote from Malcolm:

" I have just been visiting your web site and had a look at your attempts to deal with one of the most diabolical amps ever to see the light of day.

My advice to anyone given one of these thing to fix - drop it like a hot potato and run in the opposite direction. These things were doomed the moment they left the factory " .

Says it all really.

.... Phil

Reply to
Phil Allison

"Gareth Magennis"

** Thanks again.

I found this page that details the many problems techs have found with these Marshalls.

formatting link

Quote from Malcolm:

" I have just been visiting your web site and had a look at your attempts to deal with one of the most diabolical amps ever to see the light of day.

My advice to anyone given one of these thing to fix - drop it like a hot potato and run in the opposite direction. These things were doomed the moment they left the factory " .

Says it all really.

Well, what it says is what we already know, that a batch of faulty circuit boards were manufactured. Marshall have since redesigned it and the replacement seems to have sorted the problem out.

What it also points out is that any bodge is likely to cost far more in labour than simply replacing the board. Unless you happen to live in Sydney perhaps.

years ago now)

And you would still be charging the customer a load of money for leaving a faulty board in the amp.

Of course you could argue that Marshall should be offering a free exchange replacement on such boards, but that is a different debate.

Cheers,

Gareth.

Reply to
Gareth Magennis

Or read the article you showed us, which doesn't really say to give up, after all.

Reply to
dave

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