Draining Mark IV Filter Caps

[hagcel]

Just want to make sure this approach is safe for a Mark IV (B, wide 1x12 combo)

1. Unplug the amp, turn power switch on, turn the standby switch on (so the amp would be in standby mode)

2. Connect an aligator clip to the chassis

3. Connect an aligator clip to Pin 1 on V1

4. Wait 30 seconds and done?

I assume I can check that they are drained with my DMM by take black lead to ground and red lead to the + side of a filter cap?

Thanks for any help! I know that's how you do it on a Marshall or Fender but wanted to check this approach for my Mesa.

I want to clean the tube sockets and pots (by spraying contact cleaner in) and check the filter caps for bubbles and see if there are any burned up resistors, clean the grounding bus if it needs it. The amp has quite a bit of hum and random static with nothing plugged in. Could be the power in my house but figured I'd check it out. Any wires I should check to make sure they are insulated properly?

Thanks!

 

[topcat0399]

I can't believe someone didn't answer this for you.

I haven't been around lately.

Simplest way is to have amp turned on and not on standby. Have guitar plugged in with volume all the way up.

Flip amp power switch to off while striking all the strings on the guitar.

The sound of the guitar strings dying as the amp turns off is the sound of your caps discharging.

Very simple.

Good luck.

 

[yeti]

you're going to want to read up on how to properly drain caps in an amp, ANY amp, before you end up fucking killing yourself.....holy god.

no, you dont just clip alligator clips on.

no, the above method doesn't completely drain the caps, and, besides, they can recharge over time.

learn how to do it.

if you can't figure out how to google your way into finding this info, maybe you should have a tech show you.
be safe, be smart!

 

[GawlGuitar]

Safety tip........ Never use both hands and the current won't have a path through your heart. That's how the guitarist can get killed. And wear safety glasses before discharging high voltage caps.

Always treat HV electronics like it's powered and treat every firearm like it's loaded and you'll live to be an old fart like me.