quacktron 2/13/2007 9:22 AM
Schematics for a Crate VC2112R?
So I've had this amp for about six years now, and I absolutely love it. Huge sound in a small, inexpensive package. It's making a lot of hum now, especially since I'm using it with the gain cranked up. The whole chassis seems to be microphonic. Even with a guitar not plugged in the thing is ALIVE. If I poke around inside the chassis there is a microphonic "field" around the input jack and circuit around the first preamp stage. I'm pretty much a novice with tube amps, (i know how to drain a cap) but it seems like a ground issue to me. I just replaced all of the tubes and the problem is still there. Any advice? Also, I'm having a difficult time finding a schematic, can anyone help me out?

New member quacktron here, saying hello.

 
Steverino 2/13/2007 11:45 AM
Hey Mr. Quack, I'm new here too. I've never heard of a VC2112R, I own the VC3112. It's probably the best amp Crate ever made.

As far as a schem is concerned, try contacting the manufacturer for Crate, which is St. Louis Music Inc.

I found this on their site:

Owners Manuals, Schematics, Product Repair Information

For any questions concerning owners manuals, schematics, product repair, or locating a Certified Service Center in your area please contact the LOUD Technologies Inc. Service Center at 1-800-898-3211.
 
quacktron 2/13/2007 3:30 PM
Steverino,

Well, I've been calling LOUD all day, nothing but gosh darn busy signals. I'll keep trying manana. Thanks for the advice.

The VC2112R = Vintage Club 20 watts 1x12 w/reverb

2 el84's

Just took the Vintage 30 speaker out and put the stock crate back in. The cheapo stock sounds better than the celestion! vierd. I think the V30 might be more suited for a closed cabinet.

anywaze...

so.. does your crate hum and display intense microphonics when the gain is cranked way up?
 
Steverino 2/14/2007 7:17 AM
Quote Originally Posted by quacktron View Post

The VC2112R = Vintage Club 20 watts 1x12 w/reverb

2 el84's

so.. does your crate hum and display intense microphonics when the gain is cranked way up?
Sounds like one half of the 3112 I own (4 EL84s 30W)

I haven't used it in some time, but do seem to recall some pretty intense microphonics with the gain way up. The preamp tubes should have sheilds and the ouputs should have these brackets holding them in. I don't like the way the tube sockets are soldered to the pcb. I had to resolder all of them. Also, the clean/dirty switch kept crapping out and defaulting to the dirty channel, which really aggravated me since the clean channel is my favorite.

Usually it's a microphonic preamp tube that's the culprit. Try the pencil eraser trick on them and see if you can find the suspect tube. Also, check those plastic jacks. They can wear out pretty quick. I usually run my instrument cord through the handle before plugging it in.

Good Luck
 
quacktron 2/14/2007 12:56 PM
So I replaced the input jack last night, and that was it! Well, the grounding problem is solved at least.

So I popped in a new set of JJ's and it sounded great, lower noise. I then started swapping tubes with my cache, just to try different tones, and after about ten swaps the thing started sounding like shit.

Well it was about 12:30 and I'm sure the neighbors were not appreciating the importance of my gain experimentations, so I called it quits. Depressed again.

Guess I'll be back at it tomorrow night (valentines day). Maybe I busted a solder on one of the tube sockets. How did you determine yours needed replacing? Visually?
 
Steverino 2/14/2007 1:18 PM
Quote Originally Posted by quacktron View Post
So I popped in a new set of JJ's and it sounded great, lower noise. I then started swapping tubes with my cache, just to try different tones, and after about ten swaps the thing started sounding like shit.

Guess I'll be back at it tomorrow night (valentines day). Maybe I busted a solder on one of the tube sockets. How did you determine yours needed replacing? Visually?
Go back to the JJs. Let her warm up. Try to determine if the problem is temp related.

On mine, you could actually see where the automated soldering didn't adequately fill the solder "holes" where the legs of the sockets go into the board. Changing tubes often can't be good, because if you watch the board while you're pulling on them, it's flexing.
 
Enzo 2/14/2007 6:18 PM
The problem with the old input jack was that the tip grounding contact (that closes when you remove the plug) was not making good electrical contact. Thus the input is no longer grounded when nothing is plugged in. So wave your hand near it, and it makes more hum. Cleaning that contact might have saved the jack.

I don't know why, but Crate amps seem to be more sensitive to such contacts than other brands.

Since you have been manipulating the amp, check ALL the pots along the front for broken solder to their legs. Also check closely the solder to ALL the large rectangular cement power resistors.

And if you still need the schematic, send me an email with Crate VC2112R Schematic as the subject line. Send to: tmenzo at msn dot com
 
TomCarlos 5/15/2018 9:32 PM
I stumbled onto this post. I have a Crate VC2110R. I'm not crazy about the Gain and Level controls. I think I might try to modify this amp to make it as "clean" as I can get it without having to deal with the variable gain. Despite what my friend says, no way does this sound like a Marshall.

And here is a schematic for the amp.
 
glebert 5/15/2018 10:59 PM
FWIW I've found the VC amps to be really sensitive to preamp tubes. I have to go through my VC50 because I swapped some tubes out and now it is way too hot. Don't know why, but that is what mine seems like.
 
Tone Meister 5/18/2018 6:27 AM
Quote Originally Posted by TomCarlos View Post
... Despite what my friend says, no way does this sound like a Marshall...
He probably said, "it tastes like ckicken" Tom, NOT "it sounds like a Marshall."