08-12-2015, 05:32 PM
Firestone 4A22
I had this around for a while and thought I would give it a try so I recapped and checked the tubes all went well and I hooked it up to the variac and brought it up. It played good for about 2 days (not continuous) when I heard some crackling form the speaker and lost the station so I shut it down. Went back over my work and all was OK started voltage checks which ran about 20% higher than posted values and ran into a problem on the Plate of the 6K6 output tube would start to build then drop to about 2v . From there I started checking the output transformer and the primary is open. I dug into the leads to check the soldering and connection and it looked good.
I have an output transformer a PT-291 8 watt, should I use the full primary 491 ohms?
http://www.nostalgiaair.org/pagesbymodel...006233.pdf
Unfortunately the print here is not complete I have vol 15 so it was not a problem for me.
Thanks Eric
I had this around for a while and thought I would give it a try so I recapped and checked the tubes all went well and I hooked it up to the variac and brought it up. It played good for about 2 days (not continuous) when I heard some crackling form the speaker and lost the station so I shut it down. Went back over my work and all was OK started voltage checks which ran about 20% higher than posted values and ran into a problem on the Plate of the 6K6 output tube would start to build then drop to about 2v . From there I started checking the output transformer and the primary is open. I dug into the leads to check the soldering and connection and it looked good.
I have an output transformer a PT-291 8 watt, should I use the full primary 491 ohms?
http://www.nostalgiaair.org/pagesbymodel...006233.pdf
Unfortunately the print here is not complete I have vol 15 so it was not a problem for me.
Thanks Eric
