Crate VTX212 Loud Hum Whe Instrument Plugged In

[Groucho63]

Hello everybody! -I just goofed again. I bought a Crate VTX212 from a pawn shop to give my son for Christmas and although cosmetically it's in great shape, when you plug a guitar into it the thing makes a terrible hum- not effected by any controls or switching channels- goes away when you unplug the cord.

(I'm a retired car mechanic and my electronics expertise doesn't get much further than basic multimeter testing, soldering, etc...)

-I also bought him a Behringer 212 amp off Craigslist that didn't work either- my luck has to change one of these days!

Anyway, could somebody please shoot me any ideas where to start looking for what might be the problem with this Crate. I really like the looks of this old thing, have always had pretty good experiences with Crate stuff before- and it seems to work pretty well except for this hum!

Grr! Thanks in advance,

Groucho63

[DrGonz78]

Stop turning it on and immediately remove the speakers. At this point that low level hum could be an indication that there is DC voltage output of the amp. Use a multimeter, dc volts setting, to check the speaker terminal lead. Report back if we have DC voltages and don't connect a speaker up to the amp until we know that there is no DC voltage on the output. The DC will fry a speaker(s).

[52 Bill]

Stop turning it on and immediately remove the speakers. At this point that low level hum could be an indication that there is DC voltage output of the amp. Use a multimeter, dc volts setting, to check the speaker terminal lead. Report back if we have DC voltages and don't connect a speaker up to the amp until we know that there is no DC voltage on the output. The DC will fry a speaker(s).

I would think that the hum would be there all of the time if it had dc on the output, but it is a good thing to check before moving forward.

Groucho, you do mean that the hum goes away when you unplug the instrument cord and not the ac cord right?

[Groucho63]

Stop turning it on and immediately remove the speakers. At this point that low level hum could be an indication that there is DC voltage output of the amp. Use a multimeter, dc volts setting, to check the speaker terminal lead. Report back if we have DC voltages and don't connect a speaker up to the amp until we know that there is no DC voltage on the output. The DC will fry a speaker(s).

No, no DC voltage- meter just auto-ranges around

[Groucho63]

Guys- I decided to change boats mid-stream. I went ahead and took advantage of the 5 day warranty and took it back- traded for a Fender Frontman 212R -When I was a lad about my son's age I had a Fender Twin~Reverb rated back then at 100 watts (same as this one) I was just telling my son that mine had a two-button footswitch- Tremelo and Reverb- this one's has 'Channel' and 'Overdrive' (tap it again for 'More Overdrive"!!) -Where things really that much more civilized back then? Ha ha... Even though I do recall having to have had my speakers re-coned twice from running it on '10' with an old MXR Distortion+

Thank you for your help, but I thought it best to not open a can of worms that really wasn't absolutely necessary. Do you think I made the right decision? I really liked the looks of the Crate, it had DFX and all... looked somewhat like an old VOX or something (but of course it wasn't. It was a Crate. And a broken one at that.)

Thanks again guys, I mean that- and Merry Christmas!!!

[g1]

If the hum is only there when a cord is plugged into the input, and the amp otherwise seems to work, then have a close look for a bad solder connection or broken trace at the input jack.

Edit: oops, too late . Hope this one works mo' better!

[Groucho63]

If the hum is only there when a cord is plugged into the input, and the amp otherwise seems to work, then have a close look for a bad solder connection or broken trace at the input jack.

Edit: oops, too late . Hope this one works mo' better!

Hey thanks though- I really have mixed feelings about this. I really liked the Crate's looks, and that it had DFX -and wheels! -But it wasn't for me, it's for my 18 yr old son. -I think he probably liked the Crate better too, but I'm inclined to trust the Fender a little better (but maybe that's my age talking- probably not much difference in the way they're built anymore, and like I said I've probably had less problems with Crate stuff over the years) I might should have pulled the head out for at least a quick look-see, but I only had 5 days to return it, and I'm on dialysis so I never know when I might be feeling horrible.

I'm kinda gun shy right now about solid state amp failures anyway, having bought that Behringer off Craigslist and it not getting any louder than one of my kids practice amps...grrr... I guess now would be a good time to bring it out here and pull it down and try to find the problem with it. Like I say, I'm generally handy with the basics- like for instance I managed to fix a pawn shop dumpster find Peavey KB-1 by sticking an amp off Digikey in it, but much more than that I'll definitely need some help and guidance - (I think you know what you're talking about~ I've been dredging forums on the Crate and did come across a lot of opinions that they were known for nnot using enough solder on their stuff... I guess I'll always wonder... ) Hate that!

But thanks again for the reply! Take 'er easy!

[DrGonz78]

Sorry I was in a rush when I read the original post and misread the whole "when you plug a guitar into it ... terrible hum" part. Hey the Fender is a good amp and easier to work on than the crate if something should fail. When the digital part of the amp goes bad, it can be a real nightmare to repair the amp. Tell your son that you can always add effects with pedals on the front end or through the loop. Personally the effects built into the amps these days are not as versatile as stand alone effects(i.e. stompboxes etc...), but thats just my opinion. I think you made the right decision to replace a non-working amp with a working amp. Good one!