JCM2000 DSL100

[Phil Allison]

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

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message
news:bltu0u...@mid.individual.net...

There is no reason why Marshall would not have these PCB's for sale.
The last one I bought cost me just short of £50 including VAT and carriage.

I guess if you could persuade them to ship to Sydney, the VAT would be
deducted and you would pay VAT/import duty in Australia instead.

They did have a policy of only selling things that might kill people to bone
fide engineers who wouldn't kill themselves or others with High Voltage, so
you might also have to prove you are not a numpty.


If you're really stuck I have one here I could ship you, but with carriage
and import taxes and already paid VAT @20% now, its going to end up bloody
expensive.



Cheers,


Gareth.

[N_Cook]

Or you could get sculpting on what you have. Possible with small conical
cintride/diamond bits but I now have a set of cintride tile-hole cutters
for a quick neat job.
Explained on a couple of M, on my file
http://www.divdev.fsnet.co.uk/repair2l.htm
IIRC one was thermally-kicked-off conductive pcb problem at a preamp
valve and the other for output valves. Neither have bounced back to me
and one of the owners I'm in regular contact with.
You have to wonder if the replacement M boards are old stock from the
original salt? contaminated board production run

[Gareth Magennis]

"N_Cook" <div...@tcp.co.uk> wrote in message
news:ldct6l$no1$1...@dont-email.me...

No they are new boards, different colour, different screen printing.
Nobody in their right mind would comtemplate such a thing. Surely.



Gareth.

[Phil Allison]

"Gareth Magennis"

> No they are new boards, different colour, different screen printing.

** I absolutely hope that IS the case.

> Nobody in their right mind would comtemplate such a thing. Surely.

** Right mind ?? "Nutcase Kook" ??

Surely you jest ...........

FYI:

Years ago, I established beyond all doubt that the PCB leakage problem with
these models extends waaaay beyond the octal vales back into the phase
splitter and earlier stages. PCB modifications and/or the use of fans are a
dodge at best and I will never try them again.

In this case, I'm gonna make the OWNER buy the new PCB and supply it to
me.

Soooo, if it turns out to be the wrong one OR has any kind of other
problem - I can just hand it back.

There are for too many *complete idiots* involved in the chain from
Marshall in the UK to me.

Just like the smug pommy bullshitter in these videos:

https://www.youtube.com/watch?v=WeerxAO3oRU

https://www.youtube.com/watch?v=rhe7qXP08qw


Fair makes my skin crawl .......




.... Phil

[Phil Allison]

"Gareth Magennis"

>
> There is no reason why Marshall would not have these PCB's for sale.

** Double negatives like that are mind numbing.

> The last one I bought cost me just short of £50 including VAT and
> carriage.

** Was that long ago ?

> They did have a policy of only selling things that might kill people to
> bone fide engineers who wouldn't kill themselves or others with High
> Voltage, so you might also have to prove you are not a numpty.

** 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.

> If you're really stuck I have one here I could ship you, but with carriage
> and import taxes and already paid VAT @20% now, its going to end up bloody
> expensive.

** Thanks for the offer.

Is there anything special about ordering such a PCB ?

Or is the amp model number and serial number enough ?



... Phil

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message

news:bluhqb...@mid.individual.net...

Nothing special, just ask for a DSL 100 board.

Just for confirmation, both are marked JCM2-60-00.
The new board has two extra connectors, Con 15 and Con16, as well as a relay
which the old board does not. (Also Con 4 is not in the same orientation)
This is probably so it can be used in the TSL 100 as well, the 3 channel
version.
Definitely not the same PCB at all.

I think the DSL 50 also uses the same PCB, but with only 2 output valve
sockets populated, but don't quote me on that cos my memory is a bit shit
when it comes to things like that.


Cheers,


Gareth.

[Phil Allison]

"Gareth Magennis"
> "Phil Allison"

>> "Gareth Magennis"
>>
>>>
>>> There is no reason why Marshall would not have these PCB's for sale.
>>
>>
>> ** Double negatives like that are mind numbing.
>>
>>
>>> The last one I bought cost me just short of £50 including VAT and
>>> carriage.
>>
>> ** Was that long ago ?
>>
>>
>>
>>> They did have a policy of only selling things that might kill people to
>>> bone fide engineers who wouldn't kill themselves or others with High
>>> Voltage, so you might also have to prove you are not a numpty.
>>
>>
>> ** 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.
>>
>>
>>
>>> If you're really stuck I have one here I could ship you, but with
>>> carriage and import taxes and already paid VAT @20% now, its going to
>>> end up bloody expensive.
>>
>> ** Thanks for the offer.
>>
>> Is there anything special about ordering such a PCB ?
>>
>> Or is the amp model number and serial number enough ?
>>
>

> Nothing special, just ask for a DSL 100 board.
>
> Just for confirmation, both are marked JCM2-60-00.
> The new board has two extra connectors, Con 15 and Con16, as well as a
> relay which the old board does not. (Also Con 4 is not in the same
> orientation)
> This is probably so it can be used in the TSL 100 as well, the 3 channel
> version.
> Definitely not the same PCB at all.
>
> I think the DSL 50 also uses the same PCB, but with only 2 output valve
> sockets populated, but don't quote me on that cos my memory is a bit shit
> when it comes to things like that.
>

** Thanks again.

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

http://www.lynx.net/~jc/TSL122.html

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

[Gareth Magennis]

"Phil Allison" wrote in message news:bm01ok...@mid.individual.net...

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.
(Last one I bought was something around £35 +carriage +tax, that was 2 or 3
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.

[Gareth Magennis]

http://imageshack.com/a/img845/570/o62e.jpg


The old PCB is the top one.

Note Con15 below the bridge rectifier, it is connected to + and - of
rectifier.
Con 16 is below Con 8 and is just wired in paralell with it.

The old PCB has an LDR, the new one a relay.


There may be more differences, I haven't bothered to check thoroughly.



Gareth.

[Phil Allison]

"Gareth Magennis"
> "Phil Allison"

>
> ** Thanks again.
>
> I found this page that details the many problems techs have found with
> these
> Marshalls.
>
> http://www.lynx.net/~jc/TSL122.html
>
> 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.

** Wot - a single batch ??

1. How about 20 or 30 batches over a period of 5 or 6 years ?

2. How about publishing schems AND making many thousands of PCBs with 5.6k
grid suppressors substituted for 220k ?

3. Have about never informing any of their overseas agents about it ?

4. How about 10s of thousands of EL34s ( and OTs) destroyed by the stupid
problem ?

5. How about the hefty repair bills paid by Marshall owners and consequent
bad will generated against hard working amp techs who were deliberately NOT
informed of the REAL problem by the culprits - ie Marshall.

> Marshall have since redesigned it and the replacement seems to have sorted
> the problem out.

** You ARE fucking joking !!!!

You must be sucking those cunt's cocks so hard.

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

** No it fucking is not.

It is nothing short of gross consumer fraud.



.... Phil

[N_Cook]

It would be nice to nail down exactly what the problem was with the pcb
manufacture. As China made, probably affects other makes, which at lower
voltages perhaps would take longer to emerge as a problem. I posited
NaCl salt contamination to the filler material as it seems to give the
right sort of temperature / conduction graph. The problem does not
require the amps to be stored in sheds or garages, ie dampish, to induce
the fault condition.

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message

news:bm142i...@mid.individual.net...

I'm not going to respond to that, it is disingenous on far too many levels.




Gareth.

[N_Cook]

On 12/02/2014 10:20, Gareth Magennis wrote:

Knowing how precious some guitarists are, I'd rather mechanically adapt
the original board rather than swap out to what may or may not be a
sound-wise eqivalent replacement board. I've been there before, having
spent out large spondulics for (not Marshall) a manufacturer's
replacemnt board and ended up in a god-awful slanging match with an
owner because the "sound" was all wrong and resulting with me being the
time and money loser.

[Gareth Magennis]

As a matter of interest, how old is this amplifier?

It'll be part of the serial number.



Gareth.

[Gareth Magennis]

"N_Cook" <div...@tcp.co.uk> wrote in message

news:ldflvg$5tj$1...@dont-email.me...

In this case the problem may have been exacerbated by incorrect value and
possibly temperature co-efficient type of resistors fitted, if Phil's link
is to be believed, so possibly a combination of problems, not a single one.

It would be unwise, IMHO, to assume ALL PCBs in the faulty batches ended up
suffering from this problem. Any contamination/faults may have been quite
clumpy in distribution, and/or down to a single individual during their
shift.

Who knows.




Cheers,


Gareth.

[Phil Allison]

"Gareth Magennis"
> "Phil Allison"

> I'm not going to respond to that, it is disingenous on far too many
> levels.
>

** It is all simple fact, you lying pommy cunt.

Points 1,2 & 3 are detailed in the link I posted - which I seriously
doubt you bothered to read.

Points 4 & 5 are the unavoidable consequential outcomes.

You have no response because you have been caught lying.

Again.

Fuck you.




.... Phil

[Phil Allison]

"Gareth Magennis = Liar"

>
> In this case the problem may have been exacerbated by incorrect value and
> possibly temperature co-efficient type of resistors fitted,

** Regular carbon film types were fitted to early examples and later metal
film - neither were the culprits.

The first and worst case I saw ( a TSL 122 ) used metal film types.

FYI, fuckwit:

NTC resistors in the bias feed would have HELPED the problem.


... Phil

[dave]

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

[dave]

Read the last 2 letters on Phil's link. The bias problem is on the
Overdrive board.

[Phil Allison]

"dave the stinking cunt"

>> I found this page that details the many problems techs have found with
>> these
>> Marshalls.
>>
>> http://www.lynx.net/~jc/TSL122.html
>>
>> 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.
>>

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

** Malcolm does not say that either, you stinking trolling moron.





.... Phil

[Phil Allison]

"dave the trolling cunt "

> Read the last 2 letters on Phil's link.

** Don't waste your time.

> The bias problem is on the Overdrive board.

** Like hell it is.



... Phil

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message

news:bm1es4...@mid.individual.net...

Oh I see what you did there Phil, you changed this:

In this case the problem may have been exacerbated by incorrect value and

possibly temperature co-efficient type of resistors fitted, if Phil's link
is to be believed, so possibly a combination of problems, not a single one.

To this:

>> In this case the problem may have been exacerbated by incorrect value and
>> possibly temperature co-efficient type of resistors fitted,

For one who is always complaining about snipping and changing the context,
that takes the biscuit.

You lying snipping changing the context Marsupial's dirty unwiped arse.



Cheers,


Gareth.

[Gareth Magennis]

"Gareth Magennis" <sound....@btconnect.com> wrote in message
news:gIqdndJVuamLFWbP...@bt.com...

Which kind of proves "Malcolm" is talking a load of bollocks then.



Gareth.

[Phil Allison]

"Gareth Magennis = Stinking Liar"

>>
>>> In this case the problem may have been exacerbated by incorrect value
>>> and possibly temperature co-efficient type of resistors fitted,
>>
>>
>> ** Regular carbon film types were fitted to early examples and later
>> metal film - neither were the culprits.
>>
>> The first and worst case I saw ( a TSL 122 ) used metal film types.
>>
>> FYI, fuckwit:
>>
>> NTC resistors in the bias feed would have HELPED the problem.

>

> In this case the problem may have been exacerbated by incorrect value and
> possibly temperature co-efficient type of resistors fitted, if Phil's link
> is to be believed,

** Utter crap.

Some people who posted in that link HAVE worked out the real problem, ie
the PCB itself - but others ( having never seen anything like it before)
fell for red herrings.

Such a weird fault is bound to cause confusion among valve amp techs - most
of whom are not very bright .

Like you.

BTW:

Try learning Ohms Law you stinking pommy LIAR !!!!




... Phil

[Phil Allison]

"Nutcase Kook the Fuckwit Pommy Nut Case "

>
> Knowing how precious some guitarists are, I'd rather mechanically adapt
> the original board rather than swap out to what may or may not be a
> sound-wise eqivalent replacement board.

** Why were you not aborted ?

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message

news:bm1g4n...@mid.individual.net...

I learnt that once before and its a bit boring. Murphys law is a little
more interesting.

And by the way I see you have just repeated the snipped and contex changed
post of mine above.
That's not very sporting, now is it?


You stinking half dried up pool of Wallaby vomit.



Cheers,


Gareth.

[Phil Allison]

"Gareth Magennis = Stinking Liar"

>>
>>> In this case the problem may have been exacerbated by incorrect value
>>> and possibly temperature co-efficient type of resistors fitted,
>>
>>
>> ** Regular carbon film types were fitted to early examples and later
>> metal film - neither were the culprits.
>>
>> The first and worst case I saw ( a TSL 122 ) used metal film types.
>>
>> FYI, fuckwit:
>>
>>NTC resistors in the bias feed would have HELPED the problem.

>> --------------------------------------------------------------------------

>
> In this case the problem may have been exacerbated by incorrect value and
> possibly temperature co-efficient type of resistors fitted, if Phil's link
> is to be believed,

** Utter crap.

Some people who posted in that link HAVE worked out the real problem, ie
the PCB itself - but others ( having never seen anything like it before)
fell for red herrings.

Such a weird fault is bound to cause confusion among valve amp techs - most
of whom are not very bright .

While other are complete fuckwits - like you.

BTW:

Try learning Ohms Law you stinking pommy LIAR !!!!

NTC resistors in the bias feed would have HELPED the problem.

BTW2:

You drunk ?

You sure sound like you are.



... Phil

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message

news:bm1h61...@mid.individual.net...

No Phil, I don't drink during the day at work, you can do as you please.

By the way, read my post again. You know, the one you snipped. It says:

>> In this case the problem may have been exacerbated by incorrect value and
>> possibly temperature co-efficient type of resistors fitted, if Phil's
>> link
>> is to be believed,

I never mentioned NTC resistors at all. I quickly read that page before
going to work this morning and merely re-iterated that Malcolm seemed to
think the wrong type had been fitted.

Which is exactly what I said.


You lying content changing Fuckwit.



Cheers,


Gareth.

[dave]

I don't know Malcolm. The last couple letters are from someone else I
think. Or maybe not. It's not important. I've only had a couple of those
on my bench and aside from the general cheapness certainly no worse than
many other amps. Now I am in an arid climate 25.6 miles from the sea, so
that may be why I haven't noticed any 500 VDC HV peter tracks.

[Gareth Magennis]

"dave" wrote in message
news:wLCdneJfmd9-eWbP...@earthlink.com...

I've had a little bit more time to look at that web page now.

Seems to me about a lot of so called Engineers blowing their own trumpets
and becoming Superheroes for sorting it out.
But actually not really.


The first time I came across this problem, I was totally confused. What I
was seeing could not logically be happening.
I changed everything in the Output stage, but still the same symptoms.
Eventually I phoned Marshall, and spoke to one of their techs, who informed
me that yes, there was a problem with the PCB's, and yes, I should replace
it with a re-designed one.

All admitted by Marshall up front, job done, sorted.



Seems this problem is more about Ego's, than simply looking at the problem,
finding the solution, and implementing it at the least possible cost.



The best post on the site I found was this one, which kind of sums up what I
have experienced perfectly.

http://imageshack.com/a/img545/362/4pvn.jpg


Most everything else is all Me Me Me.

[William Sommerwerck]

Do you realize that when you so viciously attack people who disagree with you
(whether they're right or wrong), you destroy the atmosphere needed for an
intelligent conversation?