Bush AC2

[Radio Tech]

Hi folks

Picked up a rather tatty Bush AC2, the bottom of the case full of woodworm rot but I managed to remove the bottom and intend to get hold of a piece of 6mm ply and cut out a new bottom and glue it back in. But that only half the problem, appart from replacing those waxie caps, there seems to be some problem with two of the valve bases, these are the paxillin type and from basic tests the first valve not making good contact likewise the o/p valve being the same, it will be a long job if I am forced to replace these bases but I will try cleaning and check for dry joints, these sets are not the best to work on by any standard but we will see.

Ken

[Radio Tech]

Hi Folks

The set is being stubborn in coming back to life, I have changed all the caps (waxies and electrolytic) I looked at the voltages around the valves and the HT at the points specified on the anodes and grid 2's are all reasonable just appear to be around 10 Volts down so followed the ht back to rectifier and the resistors in line with the HT are ok I did wonder now if its the rectifier not up to scratch, just puzzling, just seems as if the hexode/ triode isn't doing what it should, the valve in there is a ECH35 but should be a CCH35, wonder now if a complete set of know good valves should be put in.

Ken

[stevehertz]

Looks like you got a job on your hands there Ken. This is where a good valve tester comes in, but saying that a lot of members say valves should or could be tested in the set. Personally I like to get a set of fully tested valves into a set, and work from there in the knowledge that they're not to blame.

[cathoderay57]

Hi Ken, the set is series heater chain using valves that draw 0.2A. the ECH35 wants 0.3A so it will be underrun at 4.2v or thereabouts instead of the expected 6.3v. With a good ECH35 you'd probably get away with it but if the valve has already lost emission it won't perform well. Ten volts down in the HT shouldn't be critical. I'd try and get a CCH35. Unfortunately, I don't have any. Best of luck with the resto! Jerry

[Cathovisor]

Originally Posted by cathoderay57

Hi Ken, the set is series heater chain using valves that draw 0.2A. the ECH35 wants 0.3A so it will be underrun at 4.2v or thereabouts instead of the expected 6.3v. With a good ECH35 you'd probably get away with it but if the valve has already lost emission it won't perform well. Ten volts down in the HT shouldn't be critical. I'd try and get a CCH35. Unfortunately, I don't have any. Best of luck with the resto! Jerry

The set should have a CCH35 in the frequency changer position as per the Bush manual, but I also seem to recall that later ECH35s had an Ih of 0.225A.