UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Roberts R200- Distorted Output

JoshWard · 21st Aug 2013, 11:36 pm

I tried an 8.2k resistor in there and I can now get the bias up to 4mA OK with the AC128 in there. I think I will try it with a silicon diode and do some tests though just in case it does work, silicon diodes are a lot cheaper than AC128s so it would be good if it does work.

The voltages were measured with positive probe to chassis. I had the same problems with the original transistors which is why I tried replacing them, with no luck it would seem!

Josh.

21st Aug 2013, 11:36 pm	#17
JoshWard Octode Join Date: Dec 2005 Location: Near Stowmarket, Suffolk, UK. Posts: 1,962	Re: Roberts R200- Distorted Output I tried an 8.2k resistor in there and I can now get the bias up to 4mA OK with the AC128 in there. I think I will try it with a silicon diode and do some tests though just in case it does work, silicon diodes are a lot cheaper than AC128s so it would be good if it does work. The voltages were measured with positive probe to chassis. I had the same problems with the original transistors which is why I tried replacing them, with no luck it would seem! Josh.