Aaaargh. Ridiculous. I had a cold joint on one of the TPs - I measured directly on one 1 ohm resistor. It works fine, now.
Ah, the sound is superb. Thank you, Mr. Pass.
Ah, the sound is superb. Thank you, Mr. Pass.
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I had the same exact problem on one channel of a different amp.
It turned out that I had soldered rca positive signal input to ground on the pcb.
Check all your wiring.
Amp has a star GND which is connected to the Chassis via a NTC. see pic 1
I did remove the PSU and BA-3 FE and now the noise is reduced to a level that it is barely audible at listening position. But still there is a little noise. Again disconnected Pre the F5T is silent
Nils
Attachments
9 wire connections onto that copper Zero Volts plate look very suspicious.
Power zero volts in could be two wires.
Power zero volts out could be two wires.
Safety connection to Chassis is one wire.
What are the other 4 wires?
I hope none of them are AUDIO references !
The audio references MUST NOT go to the PSU zero volts. This plate passes huge charging current pulses.
Those current pulses will contaminate the audio if wrongly connected.
Power zero volts in could be two wires.
Power zero volts out could be two wires.
Safety connection to Chassis is one wire.
What are the other 4 wires?
I hope none of them are AUDIO references !
The audio references MUST NOT go to the PSU zero volts. This plate passes huge charging current pulses.
Those current pulses will contaminate the audio if wrongly connected.
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where do you see 9 wires Andrew? i only see 5. 1 from each speaker Return. 1 from each amp ch. and one going to chassis ground.
there is ofcourse 2 wires comming from the 2 bridges and 2 connections from the bleeder resistors.
there is ofcourse 2 wires comming from the 2 bridges and 2 connections from the bleeder resistors.
the 2 bare leads are the bleeder resistors. 1G/Y is chassis ground. the 2 white close to the transformer is from the bridges. the 2 whites at the center is from the amp boards. the 2 blue are speaker return.
it's all good.
it's all good.
the starground IS the MAG.
but yes, it could be seperated from the PSU. but that is not the noise issue.
but yes, it could be seperated from the PSU. but that is not the noise issue.
locating the MAG on the pulse carrying PSU plate is usually the hum and buzz problem.
Wijgers,
Do you want to confirm what those wires are?
Wijgers,
Do you want to confirm what those wires are?
What's up with that grey wire between the transformer and the front plate? Looks like it's forming a loop at first glance.
if that was the problem, the hum/noise would be present even without a preamp connected.