Marshall Valvestate Bi Chorus 200

[Vass]

haha as I was reading that I thought to myself I hope he doesn't die if whatever pot is playing up contacts properly all of a sudden!!

A bit of playing around but the chassis does come out quite easily. While there you can check for any ill signs on the pcb, checkout the tube (probably a 'marshall' branded one) and as said clean up the pots and check the solder on them and the jacks.

Congrats on bringing her back man!

Hehe I am alive. Thanks for your congrats, I'm pretty happy. I'm not 100% sure how to get the chassis out, and I'm no where near 100% comfortable doing so...I don't want to eat a capacitor discharge. I would of course do all of this with the thing unplugged, but still.

What cleaner brand do you all suggest? And do I just spray it in the pot & work it a little bit?

Thanks for all your help guys. If she finally gets running good I'll try to get some tone files up so you can hear her do her thing.

Vass

[lerxstcat]

The 4 bolts on the top of the amp are all that holds the chassis in place. Unplug the speakers as well as the power cord, of course. You don't actually have to touch the inside of the PCB, just use the extension hose on the contact cleaner to spray the cleaner into the slots on the pots and jacks and switch, then turn the pots back and forth numerous times, work the switch back and forth a bunch of times, and plug a 1/4" cord in and out of each jack a number of times. Let it sit for a few minutes and then you might hook the speakers up and try it before you actually return the chassis to the cabinet. Sometimes you may have to clean some of the pots twice.

If doing it twice doesn't work, you probably have a bad part for whichever one doesn't respond to the cleaner. But contact cleaner does work wonders sometimes.

I'd go to an electronics store and just tell the salesman what you need it for, and they will steer you to the right stuff for this purpose. Don'
t get it at Radio Shack unless you don't have any real electronics stores around, because the Radio Shack stuff is less effective and you get half as much for the money.

Hell of an amp for $20, $30 by the time you buy a can of contact cleaner. Again, I am NO tech whatsoever, but I can clean the pots in an amp. I did it with my 8040 simply because I didn't have the money to take it in, and found that it's easy. Plus you need to know how to take the chassis out anyway, because you will want to replace the 12AX7 preamp tube eventually, or maybe even now to improve the sound. A $19 Tung-Sol 12AX7 would probably make the amp sound 100% better, even if you like how it sounds now. Not a necessity but just an idea for later.

[yard dawg]

Too bad he doesnt live near someone who isnt afraid to open an amp up. It would be cool for someone here to be able to help him. There are way to discharge an amp. Im sure if you google it you will find a few sites that can help you do this work safely.

[Vass]

Well, if it's as straight-forward & un-contact oriented as Lerxstcat says I might give it a shot. Like I said, I just don't want to get cooked. If getting cooked is unlikely then I'm happy.

The fact that the bass pot doesn't seem to do anything at all concerns me, but then again it might be just that it's not running right period & that will fix itself once it is.

So basically if I don't touch the angry green board, I don't get cooked?

You guys are fantastic. Really appreciate all your advice. Someday hope to reciprocate.

Vass

[yard dawg]

Do some research on how to discharge caps. Its the safest way . You may just have a bad solder joint on the bass pot. Easy fix if you can solder. Its an easy fix if you have to replace it. If you can solder haha.

If youre careful you should be ok.

[Vass]

Soldering I can handle The capacitors scare me simply because I just today learned what they look like....Little coke cans & advil with legs.

So much knowledge about so many things, so little knowledge about others, but this process is helping.

As far as discharging, I am finding on one hand plans involving resistors stuck to the end of chopsticks and on the other advice such as "use a screwdriver, you should be fine."

Fun stuff.

Vass

[Sjusovaren]

Dude, that's kickass! Congrats on what sounds like a pretty good deal! Just don't fry yourself fixing it.

[Genebaby]

The 8280 is indeed a kick ass amp, big brother to the 8240 combo, with more options front and back. I bought one new back in 92, my first "big" amp (seemed huge then, not so big now). Those original larger Valvestates sound great and mine was no exception, except it died on me after a couple of months. It got repaired but when it came back it didn't have the tone and sizzle it used to, something was missing and I couldn't explain to an amp tech what was wrong. As far as they could tell it was fine as it worked, but it didn't sound good anymore, it felt like my volume on the guitar was on about six.

I kept playing it and it developed this "strange" booming sound at stage volume so I took it for repair again. Unbelievably, they didn't fix the booming, but all the tone from before was back!! I had to take it back and sure enough, they fixed the boom and the tone was gone again. This was too much so I sold it to someone who liked how it sounded now. If it had not lost that original tone, I would have kept it forever.

[Vass]

That's awesome, hopefully I get this one squared away & it'll have the tone yours did

I fooled with it a bit today. No way really to get to the pots without pulling the chassis, so I just rolled the pots a couple dozen times on each one. Sure enough, I can get her to play with a "full" signal. Wicked loud. Still going to have to get in there to bring the pots back to life/replace them. Bass started working once the signal was going through strong. Seems like it's the midrange pot on the clean channel & the master volume that are bitchy, along with the "reverb" which is weak as hell even when it's on. Added some reverb through my Podxt just to see what it would sound like- It helped, but tweaking is needed.

Anyway, this is the most fun you can have for $10.


Vass

[Genebaby]

You got a bargain, I would have snapped it up for the original $20. I have heard 8480's and they sound great too.

Oh, I forgot to mention, the power amp is the same as the Head version, 2x100w, but with the speaker impedance used in the combo it pumps out 2x80w. The usual thing with solid state power amps, output changes with ohms of speakers used.

[Vass]

I saw that on the specs. I could never use 80 let alone 100 in my apartment so it's all good

Lol the one thing I forgot to mention was the guy was like, "I have these cords. I don't know what they do, do you want them?" 3 15 or 20 foot patch cords for free.

Vass