Well the replacement CL33 valve arrived safely via Royal Mail (even though the package wasn't marked as fragile) and earlier today I had another go at powering up the SUG91 chassis.
The valve heaters glowed once again, and the HT came up to around 245V on the rectifier cathode. Everything began to look good, but the loudspeaker remained suspiciously silent. After a couple of quick checks with the AVO it became obvious that the primary of the output transformer was open circuit!
I thought that I had checked that earlier in the restoration... but perhaps not.
I'm a bit suspicious that both of the faults have been around the output stage. Perhaps the valve suffered a catastrophic failure (excess grid current caused by a leaky capacitor perhaps) and took out the transformer?
So now I'm looking for a replacement, and the radio will have to stay unfinished for a while longer.
Keep listening!
No comments:
Post a Comment