Amp now working but loud Hum.
- Thread starter grabread
- Start date
petehall347
the brandy coffee man
supply to ground short if on secondary side of things could be many things . output devices are number 1 suspect . then the rectifiers .
if on primary transformer is shot or wiring is shorted
if on primary transformer is shot or wiring is shorted
Binkman
Lunatic Member
Pete is pretty sharp on the 220 UK transformer stuff, I'm at the 120vac in USA... wonder if elnaldo member.. could chime in. wonder if there is a thermistor in the transformer? here in USA a lot of transformers are center tapped to ground etc. just not that familiar but elnaldo comes across a lot of these situations.. hope it can help.
elnaldo
Lunatic Member
Hello, I don't think I can do better than what you are already doing.
What you posted first, (HUM) and your actual situation (shorted PS) makes me think in some rectifier or capacitor that started to fail (HUM) and finally gave up (short), but it could be HUNDREDS of things inside an amp.
I'd start disconnecting the transformer secondary from the circuit (perhaps removing a fuse is enough) and start from scratch, checking with a Dim Bulb if AC voltage is OK and the transformer is working, then I'd check the diode bridges, then check you don't have a short between - and + rails to ground, all this passive checks before connecting the AC again.
A link to the schematic or a crop of the PS section will help.
What you posted first, (HUM) and your actual situation (shorted PS) makes me think in some rectifier or capacitor that started to fail (HUM) and finally gave up (short), but it could be HUNDREDS of things inside an amp.
I'd start disconnecting the transformer secondary from the circuit (perhaps removing a fuse is enough) and start from scratch, checking with a Dim Bulb if AC voltage is OK and the transformer is working, then I'd check the diode bridges, then check you don't have a short between - and + rails to ground, all this passive checks before connecting the AC again.
A link to the schematic or a crop of the PS section will help.
grabread
Active Member
Thanks you guys are great, I really appreciate your / everyone's help Manual here..... https://elektrotanya.com/hitachi_ha_6.pdf/download.html
