Friedman Runt 50 Bias Test Point On Circuit?

[craigbeckta]

Hi,

Regarding the Friedman Runt 50 head...

Where do I measure the Bias on the circuit using a Multi Meter?

Is there any links to a tutorial video or circuit schematic?

I am not sure where to measure the MV DC on the circuit board.

Any help would be appreciate.

Thanks,

Craig

 

[Chubbs]

Hi,

Regarding the Friedman Runt 50 head...

Where do I measure the Bias on the circuit using a Multi Meter?

Is there any links to a tutorial video or circuit schematic?

I am not sure where to measure the MV DC on the circuit board.

Any help would be appreciate.

Thanks,

Craig

Haven’t seen a pic of the board but if it’s like most Marshall’s you would need pin 1 and 8(I think) connected with a 1ohm resistor to ground. I doubt those are installed from the factory but they might do that. I’d email Dave. Don’t confuse the pin 5 voltage with the bias (I’ve don’t that before).

 

[311boogieman]

Craig

I don't have a Friedmen but thought this might help. I made a very detailed biasing tutorial for my Splawn. I'm sure it is pretty similar. The safety tips alone should be very helpful for you.

https://splawnfans.proboards.com/thread/7786/amp-biasing-tutorial

I would highly recommend getting a bias probe. Even the cheap ones at $20 are well worth it but spending a bit more ($30 - $80) will really get you a much safer and much more capable option.

Good luck