Carvin Vintage 33 help

[Doc Stitches]

Help. Got a 1996 Carvin Vintage 33 amp that is blowing R52 as soon as I turn it off of standby. I replaced R53 because it was roasted and thought that would fix the problem. Still blows R52. I have one weak EL84 and one weak 12AX7...could these be the problem?

Thanks
Jim

[hasserl]

What do you mean by "blowing"? These are dropping resistors in the power supply rail dropping the voltage of the supply to the PI and preamp. Do you mean they are burning up as soon as you take it off standby?

The schematic shows these to be 1/2 watt resistors. On the VT50/Nomad/BelAir, which are very close to the Vintage 33, Carvin upped these to 1 watt resistors, probably wouldn't be a bad idea to up your's to 1 watt also. Still, they shouldn't burn up as soon as you take the amp off standby. Something in the circuit is causing a large current draw to overdissipate them that quickly.

You can try pulling all the small 9 pin tubes from the amp and see if it still causes the problem. If not you can install one tube at a time and turn the amp back on each time, when it fries the resistor you've found the faulty tube. But that is taking a risk of damaging the pcb permanently. I would build a light bulb type current limiter to plug the amp into as you work your way thru this problem to keep from damaging the pcb.

http://www.geofex.com/Article_Folders/SPO_Test.htm

[Doc Stitches]

They were burning up.

What I found was a tiny thread of solder that was shorting out 2 of the main caps. Removed it and now I have a wonderful sounding amp .....only thing now is an occassional scratchey sound somewhere in channel 1.

Thanks for the good info. I'll save it for sure.
Doc

[hasserl]

You know, you can remove the clipping diodes from the dirty channel in that amp to get a cleaner sound with more natural overdrive characteristics. Let me know if you're interested.

Hasse