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Biasing problem with '62 Princeton 6G2

6/25/2004 3:09 PM
Chris	Biasing problem with '62 Princeton 6G2 Hi, Just got a '62 brown 6G2 Princeton. Plugged it in the other day and noticed that the PT ran really hot. I decided today I should go through the amp anyway and change out the cathode bypass caps and the capacitor can. After having done that, I measured the bias using the transformer shunt method and noticed 83 and 77 mA on the 6V6s. I measured the voltage on the plates at 198 and 199 V, respectively. This equates to 15-16 watts dissipation, and I think the max for 6V6s is 12 watts. So, I thought, no problem, I'll sub in a 50k pot across the bias cap and try to adjust the bias. But I can't get the bias to change. I changed out the bias cap thinking it was shorted. Still no luck. I can't figure it out. Anybody know what I should check next? Help! Chris

6/25/2004 3:09 PM

Chris

Biasing problem with '62 Princeton 6G2

Hi,

Just got a '62 brown 6G2 Princeton. Plugged it in the other day and noticed that the PT ran really hot. I decided today I should go through the amp anyway and change out the cathode bypass caps and the capacitor can.

After having done that, I measured the bias using the transformer shunt method and noticed 83 and 77 mA on the 6V6s. I measured the voltage on the plates at 198 and 199 V, respectively. This equates to 15-16 watts dissipation, and I think the max for 6V6s is 12 watts. So, I thought, no problem, I'll sub in a 50k pot across the bias cap and try to adjust the bias. But I can't get the bias to change. I changed out the bias cap thinking it was shorted. Still no luck. I can't figure it out. Anybody know what I should check next?

Help!
Chris

Replies:

Wild Bill Chris, 198 volts on the 6V6 plates ... -- 6/26/2004 8:20 AM