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Re: Looks like you need....

Posted by Russ57 (A) on December 30, 2003 at 06:30:05

In Reply to: Re: That's nothing compared to what your Asylum friends can teach you to do:) posted by Raver on December 29, 2003 at 12:56:43:

Two diodes, say 100 volt and 5 amp or better, and three caps, a 150uF, a 250uF, and a 50uF with a voltage rating of 50 VDC or better oughta do it. Just remember that the caps have the positive lead connected to ground! Remember to pull your tubes when you fire it up and check for proper bias voltage. Once you feel the voltage is okay then put in the 12AX7's and recheck before putting in the output tubes. One pair of 12AX7's gets their heater voltage from this bias supply so they will give you a visual indication of bias voltage. Quite likely that you will have to make some slight resistor value change to get proper heater voltage. It looks like that resistor is R68, a 47 ohm 5 watt resistor. Measuring voltage drop across it will give you current and with that then you can calculate the new resistor value via ohms law (voltage drop across resistor equals amps times ohms).

The main can cap is a different job. You appear to have two multi section caps, C53 and C24. The first cap next to the rectifier tube, a 20uF should be no larger than a 40uF and should have a voltage rating around 500VDC. The rest of the caps can pretty much be whatever size you like and 450VDC rating should suffice. You can buy new can caps or you can wire in a suitable radial or axial replacement cap under the chassis. Something like a Solen would be nice for the first cap and Panasonic electrolytics would be fine for the reast...say around 50 to 100uF each at 450VDC. New power supply caps such as I mentioned above will make a big difference in the units performance.

Russ

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