Hi Mcgreg66,
I had hum on my F5. I tried everything, moving wires around, making sure they were twisted, hum busting circuits etc, but what eventually worked was tipping the antek transformer up perpendicular to the amp base.
Then I got the same thing on my Aleph J, built using the same Antek, rotating the transfo didn’t help. So tried replacing my twisted hookup wire for inputs with coaxial cable, Mogami w2330 I think, and that did the trick.
I had hum on my F5. I tried everything, moving wires around, making sure they were twisted, hum busting circuits etc, but what eventually worked was tipping the antek transformer up perpendicular to the amp base.
Then I got the same thing on my Aleph J, built using the same Antek, rotating the transfo didn’t help. So tried replacing my twisted hookup wire for inputs with coaxial cable, Mogami w2330 I think, and that did the trick.
Hifi Porn
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have you tried a different pre-amp? different cables? is the chassis grounded?
Hey mcgregg66,
I’m sorry you’ve got the dreaded hum. I’ve been there. I’ve been looking at your pictures on my phone. I’m just throwing this out there and it could just be a weird reflection but I noticed what looks like unsoldered leads coming up through some of the neg rail pads on the PSU. I’m attaching a close up screen grab.
I’m sorry you’ve got the dreaded hum. I’ve been there. I’ve been looking at your pictures on my phone. I’m just throwing this out there and it could just be a weird reflection but I noticed what looks like unsoldered leads coming up through some of the neg rail pads on the PSU. I’m attaching a close up screen grab.
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Only PSU ground is connected to star ground via thermistor!
And V+ and V- grounds are connected on board!
http://i198.photobucket.com/albums/aa276/aeroplane_album/F5PSUschematic.jpg
The yellow/green wire is transformer shielding connected to starground!
And mains inlet safety ground goes to starground!
Can’t find anything wrong
Thanks but I didn’t used these.....the thermistor is wired under the board to ground...
-same color of input wires , be sure that you didn't swap wires between hot and gnd
- you grounded neg input on pcbs ?
-try connecting one fat wire directly between two channel pcbs , their main ground points ........ in other words - bridge two channel gnd points in shortest way possible , to determine is there hum culprit
- you grounded neg input on pcbs ?
-try connecting one fat wire directly between two channel pcbs , their main ground points ........ in other words - bridge two channel gnd points in shortest way possible , to determine is there hum culprit
Is it wired underneath?
Nevermind I see that it’s wired underneath but is it connected to the negative rail only? The green wire connected to the thermistor?
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I had a hum problem with my F5 which I finally solved by rotating the transfo. However I got a lot of good suggestions. Here’s the initial post:
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1543.html#post4986983
AndrewT helped me out and gave me some pointers on how to improve my wiring:
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1548.html#post5000555
Also, per Andrew again, I always ground my transfo shield as close to the transfo as possible, shortest possible wire. Seems to work. You can see it, a purple wire to the right of the transfo, in the attached image.
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1543.html#post4986983
AndrewT helped me out and gave me some pointers on how to improve my wiring:
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1548.html#post5000555
Also, per Andrew again, I always ground my transfo shield as close to the transfo as possible, shortest possible wire. Seems to work. You can see it, a purple wire to the right of the transfo, in the attached image.
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now , plug in interconnects , connect two RCA gnds on other (free) end of interconnects , power on ;
what's happening ?
