Crate Vintage Club 30 electronics help...

[jndietz]

Hey everyone, I have a Crate Vintage Club 30 that isn't outputting any sound. Last week, the overdrive channel stopped working on it and only the clean channel worked. A few days later, the clean channel started breaking up and eventually stopped working as well. Now, neither channel outputs sound. The tubes were brand new around the March/April time frame and were biased by a technician.

Where should I start to troubleshoot this? This amplifier has been in the shop too many times for me to pay someone to fix it and would like to learn amplifier electronics.

Thanks!

 

[MatchBookNotes]

simple economics; Sell it for what you can and buy a reliable amp.

 

[dementedchord]

well the first thing to do is cop a schematic for it... i just checked the amp sites i have bookmarked and i didnt see yours listed.. so if ya can find one i'll get you started... and BTW ya might want to move this to the diy forum...

 

[jndietz]

simple economics; Sell it for what you can and buy a reliable amp.

i thought about it. i love how this amp sounds though i can't just 86 it

well the first thing to do is cop a schematic for it... i just checked the amp sites i have bookmarked and i didnt see yours listed.. so if ya can find one i'll get you started... and BTW ya might want to move this to the diy forum...

I found this:

http://www.blueguitar.org/new/schem/misc_amp/crate_vc3112pre.gif

 

[jndietz]

The power section is at that site also...
http://www.blueguitar.org/new/schem/misc_amp/crate_vc3112pow.gif

Are the tubes glowing as they are supposed to? All lamps light that are supposed to?

Try some easy stuff first....
The amp shows as having an effects loop jack. That jack has switching in it to enable the signal to pass when there is no jack plugged into it. Occasionally the contacts get dirty and prevent the through signal from passing. Try jacking in and out a guitar cable plug several times and see if the contacts may clean up and make contact.

If that doesn't help you can possibly determine if the preamp section or the power amp section isn't working by sending a signal (guitar and a pedal effect) into the return of that jack. It looks like from the schematic you can just plug into it with a regular guitar cable to hit the return. If you get sound this way it sort of proves the power amp is working and the preamp section has a problem. Conversly if you get no signal the power amp or power supply may have an issue.

With the amp not powered so the tubes are cold to the touch, wiggle the tubes in their sockets. One or two could have loosened up and lost connection. The small tubes are 12AX7's. you could try wiggling them while the amp is powered as they shouldn't be too hot to touch.

Keep in mind that if you attempt to pull the chassis, there are lethal voltages under there that can knock you on your ass or potentially kill you.

All of the tubes appear to be glowing. I can't tell on the preamp tubes because they have those covers over them. I'll have to take it apart to see them. Otherwise, I just plugged my guitar into the effects loop and i'm getting sound out of it. no sound coming out of the "input" jack, though. so something is wrong in the preamp section?

 

[jndietz]

Ahh.. the culprit.

Well, after taking the amp apart I found the culprit:

After further investigating, I wiggled the tube around and then gave it a tiny tug. The tube was cracked at the base.

What I want to know is, how the hell did this happen? Especially since I literally never move this amp around?

 

[dementedchord]

well then looks like a pretty easy fix... glad you didn't just sell it??? down load those schemos ... never know when we'll need them next... or who will need them for that matter... congrats...