2203X Schematic?

Since it’s a current production model, you might have to try and find an authorized Marshall service center and plead your case for a schematic. Good luck with that, though.

Guitar Center in Santa Maria, Crookedfornia?

Maybe these guys:

CONTACT

Contact Desert Amplifier Repair with any questions, concerns, or feedback.
desertamplifierrepair.com desertamplifierrepair.com
 
Don't know if this is what you're after but it's a 2002 revision schematic, that includes the FX Loop

 
Clockworkmike said:
Don't know if this is what you're after but it's a 2002 revision schematic, that includes the FX Loop

Click to expand...
Thanks appreciate your efforts.
This amp is kind of a mystery...
I haven't actually seen it but, it blew the cathode resistors in the preamp, fried the filament balance resistors humdinger thingger, fried the filaments in the tubes, and rendered itself FUBAR.
And I have little clue why...never seen this happen before. :run::run::run:
Totally FUBAR.
 
Amp Mad Scientist said:
Thanks appreciate your efforts.
This amp is kind of a mystery...
I haven't actually seen it but, it blew the cathode resistors in the preamp, fried the filament balance resistors humdinger thingger, fried the filaments in the tubes, and rendered itself FUBAR.
And I have little clue why...never seen this happen before. :run::run::run:
Totally FUBAR.
Click to expand...
Isn't another Bias Drift is it? Same problem, new amp?
 
Clockworkmike said:
Isn't another Bias Drift is it? Same problem, new amp?
Click to expand...
It's more like the mains power is shorting to the chassis somewhere, or the electricity was wired wrong hot and ground reversed. (chassis and ground were energized?)
That's the only explanation I have so far but not really sure what happened, it's bizarre never seen anything like it happen before.

Quote:

Preamp tube 1: Pin 5 to 9 open (heater element). C1 was shorted (checked with R1 lifted). R1 and R2 ok.

Preamp tube 2: Pin 5 to 9 open (heater element). R11 visibly burned. R12 ok.

Humdinger, R31, R32, VR2 all open (not visibly burned)

All other resistors to ground checked and OK. Long Tail Pair resistors were OK.

Tube 5, EL34: pins 2 to 7 open. Pins 7 to 8 shorted (heater filament to cathode short).
 
Amp Mad Scientist said:
The consensus was:
Inside the power transformer, the HT winding and the filament winding are shorted together.
I think the power transformer ate lunch.
Click to expand...
How can this happened? A defective power transformer? What brand is this transformer? A Dagnall or MAV(Transformers built by Marshall in Vietnam)?
Current Marshall Transformers are MAV on all his amps. My '23 JTM45 has MAV transformers but filter choke it's Dagnall.

IMG_20240108_172856_copy_1228x1632_1.jpgIMG_20240108_172516_copy_1632x1228_1.jpgIMG_20240112_132504_copy_1228x1632.jpg
 
marshalltsl said:
How can this happened? A defective power transformer? What brand is this transformer? A Dagnall or MAV(Transformers built by Marshall in Vietnam)?
Current Marshall Transformers are MAV on all his amps. My '23 JTM45 has MAV transformers but filter choke it's Dagnall.

View attachment 100650View attachment 100651View attachment 100652
Click to expand...

The wrong speaker impedance
often causes arcing on the tube socket between pins 2 (filament) and 3 (plate).
And considering that, the same type arcing may have occurred inside the transformer.
It's going to overheat the insulation of the transformer windings.
Just a theory; but plausible.
Or,
the tube sockets are damaged: there's a carbon track forming / burning between filament and plate on the tube sockets.
It may or may not be visible.
I have seen this happen pretty frequently because people ignore the speaker impedance happens all the time.
 
I had a whole rash of fried power transformers voltage spikes my guess I seen them after the fact
a few years ago in Sitka Alaska the step down transformer shorted out from the power company anything thing that was plugged in
to power got 16,000 volts AC cost the power company millions. when the power goes out and they switch over to generator power
spike city.
 
Amp Mad Scientist said:
The wrong speaker impedance
often causes arcing on the tube socket between pins 2 (filament) and 3 (plate).
And considering that, the same type arcing may have occurred inside the transformer.
It's going to overheat the insulation of the transformer windings.
Just a theory; but plausible.
Or,
the tube sockets are damaged: there's a carbon track forming / burning between filament and plate on the tube sockets.
It may or may not be visible.
I have seen this happen pretty frequently because people ignore the speaker impedance happens all the time.
Click to expand...
So regardless of either event, an impedance mismatch was the likely culprit?
 
mcblink said:
So regardless of either event, an impedance mismatch was the likely culprit?
Click to expand...
Yes probably
and the sad thing is: no matter what you tell people to stop it from happening,
they are likely to ignore all warning and do the very same thing again.
If there's one thing that musicians are in complete denial of: it's speaker problems and speaker impedance.

Trying to get a guitar player to test and fix speakers: is like pulling their teeth out.
They will evade it and avoid it, to the ends of the earth.

if sound comes out of the speakers: "nothing could be wrong." You know how many times I have fought this idiocy?
Then, the amp blows up again:
it's the technicians fault.
It's caused by JJ tubes, which are ALL defective.
But it is NEVER caused by the wrong impedance speakers. (because my imagination told me so.) And if I imagine it, it MUST be true.
 
If this 2203x is the same amp I suspect it is, we're dealing with multiple cabinets and multiple speaker types, and it's affected both a 4100, and now this 2203x.

Perhaps I should gently suggest that someone RTFM again. No fun jamming when the other guy's gear is kaput lol
 
In my younger, dumber days, I smoked a brand new Mode Four just fifteen minutes after bringing it home, then smoked its replacement about 3 months later. Didn't know why it happened until I had it sent back to Marshall, who in turn had a tech in my state fix it: impedance mismatch from hell. Needed 2 16 ohm cabs to run it in fullstack mode and I bought 2 of the matching Mode Four cabs but they were the 400w series, which are only 8ohms.

Like this? Fried the power transformer and some of the initial components within the power amp section. Tech called and asked " What in the living hell did you do to this?!?" And that's when I learned a valuable lesson.
 
Clockworkmike said:
In my younger, dumber days, I smoked a brand new Mode Four just fifteen minutes after bringing it home, then smoked its replacement about 3 months later. Didn't know why it happened until I had it sent back to Marshall, who in turn had a tech in my state fix it: impedance mismatch from hell. Needed 2 16 ohm cabs to run it in fullstack mode and I bought 2 of the matching Mode Four cabs but they were the 400w series, which are only 8ohms.

Like this? Fried the power transformer and some of the initial components within the power amp section. Tech called and asked " What in the living hell did you do to this?!?" And that's when I learned a valuable lesson.
Click to expand...
When I was a kid
I plugged a brand new Marshall head into a speaker cabinet with a shielded guitar cable.
Lasted about 30 seconds before the output transformer lunched.
I guess we all did some dumb things when we were kids.
 
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