These are built in China for a UK retailer in York (UK)
Build quality quite good in general, I had a failure which I traced to the power transformer with an open-circuit thermal fuse buried in the primary winding. Dismantled transformer, reassembled it & discovered the NPN output device short circuit
Has anyone got a schematic for the power amp section? Importer/retailer will not supply one & not disclose who build them in China
Output pair are 2SD1047 & 2SB817
I have tried replacing both with a pair of 2SC5200 & 2SA1943 but to no avail
Every other semiconductor has been removed, checked & is OK
The only difference between 2SD1047/2SB817 & 2SC5200/2SA1943 that I can see is that the presence of on-chip ballast resistors on the 1047/817. Would this make a difference?Pin outs, VCEO & IC are equal/ better on the 5200/1943
There must be something else hence need for a schematic
Can anyone help?
Build quality quite good in general, I had a failure which I traced to the power transformer with an open-circuit thermal fuse buried in the primary winding. Dismantled transformer, reassembled it & discovered the NPN output device short circuit
Has anyone got a schematic for the power amp section? Importer/retailer will not supply one & not disclose who build them in China
Output pair are 2SD1047 & 2SB817
I have tried replacing both with a pair of 2SC5200 & 2SA1943 but to no avail
Every other semiconductor has been removed, checked & is OK
The only difference between 2SD1047/2SB817 & 2SC5200/2SA1943 that I can see is that the presence of on-chip ballast resistors on the 1047/817. Would this make a difference?Pin outs, VCEO & IC are equal/ better on the 5200/1943
There must be something else hence need for a schematic
Can anyone help?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.