19-05-2013, 09:49 PM
Latest update;-
Audio amp probs with trimpots falling apart some dry joints and a very strange transistor, this measures on a DVM from each pin the same. Putting it on the HFE test provides variable but repeatable results as an NPN device but nothing if PNP selected. The Tranny in question was one of the drivers, substituting it restored the functionality.
FM now works quite well. AM is humming and showing signs of instability. The -24V line is only 22V and the O/P from the bridge rec is about 10V low, Changing the caps produced no change. It appears that something is pulling a lot of current from this line, according to the volt drop on the series 22Ohm res about 80mA. Will look at this prob in the next day or two. I reckon this will be the last thing I do with 3 legged fuses.
Instead of doing a FET grid dip meter next I'll do one with a DL96 if I can find one.
Mike
Audio amp probs with trimpots falling apart some dry joints and a very strange transistor, this measures on a DVM from each pin the same. Putting it on the HFE test provides variable but repeatable results as an NPN device but nothing if PNP selected. The Tranny in question was one of the drivers, substituting it restored the functionality.
FM now works quite well. AM is humming and showing signs of instability. The -24V line is only 22V and the O/P from the bridge rec is about 10V low, Changing the caps produced no change. It appears that something is pulling a lot of current from this line, according to the volt drop on the series 22Ohm res about 80mA. Will look at this prob in the next day or two. I reckon this will be the last thing I do with 3 legged fuses.
Instead of doing a FET grid dip meter next I'll do one with a DL96 if I can find one.
Mike
