Marshall Power Brake troubleshooting

This is what it sounds like, when cones cry.

Moderators: VelvetGeorge, BUG

Post Reply
User avatar
rgorke
Senior Member
Posts: 4509
Joined: Fri Feb 08, 2008 11:37 am
Just the numbers in order: 13492
Location: Drought Ravaged SoCal

Marshall Power Brake troubleshooting

Post by rgorke » Fri Apr 29, 2016 12:15 pm

A few questions for those of you who have one. When I put a cable into the input, it reads only 1.5 ohms. Shouldn't it read 8 or 16 ohms depending on the switch position? It reads the same at every attenuation and at load, with or without a cabinet plugged in. I have checked and even substituted the 8r2 resistor...same reading.

Also, just recently, the tone was very bright, thin, and broken glassy sounding. Switching out attenuators for my Alex, the tone was back to "normal" (I'll say good, but that is subjective).

So, for those of you who have a Power Brake, could you check what resistance reading you get on the input? I do realize that inductance and resistance are different but shouldn't the resistance be higher with a static signal i.e. A meter?

Thanks,
"If you make a mistake, do it twice and smile and let people think you meant it." Jan Van Halen.

sniperschool
New Member
Posts: 27
Joined: Tue Jan 19, 2010 10:28 am
Just the numbers in order: 7

Re: Marshall Power Brake troubleshooting

Post by sniperschool » Fri Aug 12, 2016 7:12 pm

I have a few PB's so will check of you after the weekend and report back

sniperschool
New Member
Posts: 27
Joined: Tue Jan 19, 2010 10:28 am
Just the numbers in order: 7

Re: Marshall Power Brake troubleshooting

Post by sniperschool » Sun Aug 14, 2016 10:51 am

One of mine reads 2ohms and the other 1.9ohms
Not sure if that means yours is low or within tolerance
Sean

User avatar
VelvetGeorge
Site Owner
Posts: 7216
Joined: Tue Oct 14, 2003 5:12 pm
Just the numbers in order: 13492
Location: The Murder Mitten
Contact:

Re: Marshall Power Brake troubleshooting

Post by VelvetGeorge » Mon Aug 15, 2016 1:29 pm

If you take the lid off you should be able to see the inductor and capacitor on the board. These are typical failures. You will likely smell if one or both are bad.

george
Check out Plexi Replicas for my personal amp builds...
Image

Post Reply