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Vintage threads from the first ten years

Re: JCM 800 #2210

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12/15/1999 10:54 PM
Gil Ayan	Re: JCM 800 #2210 The schematic for the 2210 is in Doyle's Marshall book. I don't have a scanner with me, but I do have the book. If someone can't scan that for you, send me a snail mail address and I will be glad to send you a photocopy of the schematic. Gil

12/16/1999 3:59 AM
Stan Bailey	Wow, thanks for the generous offer Gil, your too nice! I e-mailed Pat's schematics, but if that doesn't work out I may take you up on your offer. Stan

12/16/1999 3:36 PM

Geoff Van Brunt

I have a 2210, or used to depending on how you look at it. It too sounded thin and lifeless to me, not to mention the interaction of the clean and dirty controls and noisy switching chip they used. I gutted it and made it into a combination of a 1959 and 2204 type heads. It sounds great now.

It's a great platform for mods considering it has 5 preamp tubes, a huge 3 spring reverb pan and matching transformer.

GVB

12/16/1999 4:03 PM
anon	Re: JCM 800 #2210- site with schems http://sloth.wcug.wwu.edu/~jamie/GIF/ The preamp is the same as in model 2205

12/16/1999 5:24 PM

quote:
"The preamp is the same as in model 2205"

Unless someone went inside and changed everything, it does not appear to be the same circuit. Thanks though!
Stan

12/16/1999 7:39 PM
Geoff Van Brunt	The 2205 & 2210 preamps are the same. I have both schematics and there are no differences. However, there have been a few small changes with differnet revisions of these amps. Are you sure you have a 2210? GVB

12/16/1999 11:44 PM

Ok, this is what I can see without pulling out the pcb.

V1A:
Ra = 100K
Rg = no resistor
Rk = 1.5K
Ck = .1uF

V1B:
Ra = 220K
Rg = 6.8K from V1A grid (soldered on pins 2 and 7)
Rk = 2.7K
Ck = .68uF

V2A:
Ra = 220K
Rg = no resistor ( signal taken from middle of 1M gain pot.
Rk = 1.5K
Ck = .1uF

V2B:
Looks like cathode follower.

Also, there are 4 BC182 NPN transistors in there. Switching? I don't see the IC that is on the 2205 schematic. The PI is a little different in R values as well.
Where is V1B on schematic? My copy is very poor, but I swear the other part of the first tube is not there.
Man, I sure do love point to point. Screw this trying to figure out pcb traces. The only markings on the amp are:
Front Panel - JCM 800 Lead Series
Back- Model 2210 written in. Maybe a screw-up?
You say this is the same as a 2205, but I would love to have the 2210 schematic so I can confirm this for myself. Thanks for your reply.
Stan

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