Just a few notes on one of these i picked up cheap as dead.
The 1Amp fuse on the a/c transformer board was blown and I checked the DC power supply to find only 1.6Ω across the bridge rectifier! That might have some bearing on it!
I thought it might be one of the 2 transisorts on the output of the power supply, which seem to serve as stabilisers- but no!
It was 2 of the output transistors (darlington) that were shorted collector to base (1.3Ω) I removed the offending and at least had an amp with one channel working.
Ordered 2 new ones 2SB1254 + 2SD1894- and its all up and running. it does have the annoying selector switch issue which is probably caused by age/misuse oxidisation- but i doubt Ill be bothered to desolder it as its a fairly fragile looking device and threads on here are mixed about swapping them out for a 'traditional' type.
The reason the Darlingtons were shorted was probably the cracked solder joints on the sc2240 transistor -
The 1Amp fuse on the a/c transformer board was blown and I checked the DC power supply to find only 1.6Ω across the bridge rectifier! That might have some bearing on it!
I thought it might be one of the 2 transisorts on the output of the power supply, which seem to serve as stabilisers- but no!
It was 2 of the output transistors (darlington) that were shorted collector to base (1.3Ω) I removed the offending and at least had an amp with one channel working.
Ordered 2 new ones 2SB1254 + 2SD1894- and its all up and running. it does have the annoying selector switch issue which is probably caused by age/misuse oxidisation- but i doubt Ill be bothered to desolder it as its a fairly fragile looking device and threads on here are mixed about swapping them out for a 'traditional' type.
The reason the Darlingtons were shorted was probably the cracked solder joints on the sc2240 transistor -