#1
Hi everyone.
A friend of mine has remade all the electronic in my gibson. I bought new gibby pots, etc and handed it to him. When I got my guitar back, I plugged it into my amp and found a horrible harsh noise and low volume/messed up wierd noises. I decided to unplug it and bring it to a pro tomorrow. BUT!!! I plugged another guitar and now my amp seems to have a constant humming that im not sure it had before trying out my les paul. It might be all in my head but owh god!

So, can it??
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#2
Is this your new 800?

And no- it shouldn't. Most amps have a 1Mohm resistor to prevent problems from running the amp with no guitar plugged in. (open circuit)

I'm not sure about having one shorted......
Last edited by R45VT at Mar 19, 2012,
#3
Yeah!!

It might be all in my head though.
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#5
Quote by CodeMonk
Sounds like your friend may not have done a good job.
Check ground connections, cold solder joints

No, it won't hurt your amp.


You are my jesus. Amen
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#6
And the hum could be bad power tubes, loose connections, bad grounding again.
Or maybe tubes need to be re-seated.
Even new.
I once repaired a peavey amp for a band that was going through town.
It had 2 input jacks. They mentioned that one of the jacks never really worked properly.
The problem in that case was that jack wasn't fully soldered on the PCB. It looked like it came that way from the factory.

BUT...DO NOT TAKE APART THE AMP YOURSELF. LETHAL VOLTAGES ARE INSIDE.
Or be VERY VERY careful. DO NOT touch any bare wires or PCB connections.

You can drain the capacitors, which is what any semi-intelligent amp tech would do.
Amp techs that never do that probably don't exist. They're dead.


Most people should be able to replace or re-seat tubes though.
Last edited by CodeMonk at Mar 19, 2012,
#7
Pull all the tubes out and plug them back in again. Use a bit of contact cleaner on the pins if you have it.
You should buy yourself a complete set of spare tubes (in a 2203 I'd run JJ ECC83S and/or JJ ECC803) and test each tube by substituting each tube one by one and playing it for 10 mins or so. You shouldn't expect all the tubes to be 100%. Your plan now should be to find the perfect tubes to suit your amp - it deserves it. I'd be hunting down NOS preamp tubes over the next couple of years if I were you.
You can get away with a lot in the power amp of a 2203. I'd go for in decreasing order, SED =C=, JJ or Shuguang. That is also decreasing order of price too. All three will work very well. Shugs work surprisingly well in a Marshall but SED are best.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
Quote by Cathbard
Pull all the tubes out and plug them back in again. Use a bit of contact cleaner on the pins if you have it.
You should buy yourself a complete set of spare tubes (in a 2203 I'd run JJ ECC83S and/or JJ ECC803) and test each tube by substituting each tube one by one and playing it for 10 mins or so. You shouldn't expect all the tubes to be 100%. Your plan now should be to find the perfect tubes to suit your amp - it deserves it. I'd be hunting down NOS preamp tubes over the next couple of years if I were you.
You can get away with a lot in the power amp of a 2203. I'd go for in decreasing order, SED =C=, JJ or Shuguang. That is also decreasing order of price too. All three will work very well. Shugs work surprisingly well in a Marshall but SED are best.


Right now, ive got some sovtek powertubes and JJ EL34's. I'll probably buy new tubes next week. I'll take in considerations the ones you suggested. Thanks a lot buddy!
To buy:

Line 6 MM4
Voodoo Lab power
Mesa Boogie Single rectifier
Done
Boss TU-3 Done
Shure SM58 Done



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#9
I've got Shuguang EL34's in my JCM900 (it's modded so it isn't shrill like a normal 900) and they work quite well. The power amp in the 900 is pretty much the same as in yours, it's the preamp they screwed up in the 900 and I've fixed the worst of that. The Shugs are miles ahead of the Sovteks.
In the preamp of a Marshall it's JJ if you can't afford (or find at a good price) NOS tubes. I wouldn't bother with anything else with the possible exception of Shuguang 12AX7C or maybe Gold Lions (but I don't have much experience with the new Genalex valves.)
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Mar 19, 2012,
#10
Quote by Cathbard
I've got Shuguang EL34's in my JCM900 (it's modded so it isn't shrill like a normal 900) and they work quite well. The power amp in the 900 is pretty much the same as in yours, it's the preamp they screwed up in the 900 and I've fixed the worst of that. The Shugs are miles ahead of the Sovteks.
In the preamp of a Marshall it's JJ if you can't afford (or find at a good price) NOS tubes. I wouldn't bother with anything else with the possible exception of Shuguang 12AX7C or maybe Gold Lions (but I don't have much experience with the new Genalex valves.)


So I should go for some shuguang in the power amp section and some SED in the preamp? I'll check those out on ebay.
To buy:

Line 6 MM4
Voodoo Lab power
Mesa Boogie Single rectifier
Done
Boss TU-3 Done
Shure SM58 Done



OUCH MY WALLET