Help Discharging Power Supply on Ampeg vh140c

[DERMIN]

Hello,

I've been doing some research on the best way to drain the voltage from my Ampeg vh140c solid state head. I am fairly new to the amp repair game and would like to know the best(& safest)  way to drain the power supply on this amp specifically. I've grabbed a copy of the schematic here
http://www.eserviceinfo.com/index.php?what=search2&searchstring=Ampeg+VH140C+guit+amp.pdf

Am interested to know if this unit has bleed resistors already installed or do I need to make a discharge tool? Also how well does the method of hooking up a guitar and playing it as you disconnect the unit from the power source work?


Thanks in advance for any advice!

[joecool85]

You're going to want to check for voltage across the power supply caps with a voltmeter.  If there is any voltage present you will want to drain it.  You can use a large resistor, a light bulb, or a screwdriver (not recommended since it can be potentially really dangerous, though it has been done) across the two leads on the power cap.

**edit**
If this is too vague, let us know.  No point in you getting hurt "just trying" when you don't fully understand.  This can be lethal.

[DERMIN]

Thanks for the reply, yes I do understand where your going with this. I will be checking cap voltage before I touch any components and will use a large resistor if there is still voltage present.
This being said, I have never actually done something like this myself before, so I wanted to get as much information as I could before opening the unit. Also I'm not that great at reading wiring diagrams so maybe there was something I was missing in the design that would aid in the discharge of voltage.
If you have any other thoughts..any at all, let me know...cant ever have too much info

[J M Fahey]

Solder permanently a 4700 ohm resistor, 1 watt , across each capacitor.
It will not affect normal use but will discharge those big caps in a few minutes when off.