Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: Rynlander on May 11, 2015, 08:04:46 AM

Title: Draining capacitors in a Crate VTX200S
Post by: Rynlander on May 11, 2015, 08:04:46 AM
The way that the circuit boards are mounted internally, there's no access to the pins on the caps without first unmounting the entire circuit board that they're connected to and then flipping it over first.  Is there an alternative way to discharge them?  Any help would be greatly appreciated.  This amp seems to be designed to be impossible to work on.
Title: Re: Draining capacitors in a Crate VTX200S
Post by: Enzo on May 11, 2015, 01:18:01 PM
The nice thing about a circuit is that it is, well, a circuit.  Everything is connected to something else.  The pins on the caps may be underneath, but they connect to other things.  The rectifier diodes that feed the cap are probably where their leads are exposed to you.  I don't know the amp but it appears to be solid state, which means there are no multi-hundred volt power supplies.  I suspect the power in this will discharge all by itself pretty quickly.   get out your meter, turn the amp off, and measure if there is any voltage still in the system.

I will guess it uses chip amps for the two power amps.  If it were transistors, then the collectors and eemitters of the power transistors would be connected pretty much directly to the power rails, so a clip lead to ground either of those would do it.  Chip amps are harder to get clean onto a pin, but find some other component connected to it to ground off.
Title: Re: Draining capacitors in a Crate VTX200S
Post by: Rynlander on May 11, 2015, 02:53:51 PM
Thanks a ton Enzo.  I'm new to these forums, but have learned a lot in here.  Much appreciated.
Title: Re: Draining capacitors in a Crate VTX200S
Post by: Enzo on May 11, 2015, 04:40:52 PM
Oh, well welcome to the forum too.
Title: Re: Draining capacitors in a Crate VTX200S
Post by: Roly on May 11, 2015, 06:33:56 PM
Quote from: EnzoThe nice thing about a circuit is that it is, well, a circuit.
:lmao:   :dbtu:



Hi Rynlander, welcome.


Big rack amps with humungus beer-can caps aside, I've never really found the need to discharge the power supply caps in s.s. amps.