Problem with new Aleph J build

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That loaded ripple doesn't seem like a problem. I'd hazard a guess that your hum is ground loop related.

When you have the amp disconnected measure the current drawn by the PSU - put your ammeter between the transformer and the bridge. It shouldn't be more than a few mA, whatever the bleeder resistors pull.
 
That loaded ripple doesn't seem like a problem. I'd hazard a guess that your hum is ground loop related.

When you have the amp disconnected measure the current drawn by the PSU - put your ammeter between the transformer and the bridge. It shouldn't be more than a few mA, whatever the bleeder resistors pull.

Did some measurements, after having disconnected the PS board from the amp boards. The measurements are:

Idle current draw: 13-14mA on both the rails

AC at the rails: +/- 25mV

Cannot find any fault with the measurements.

Then I removed all the 15000uF caps and measured the DC resistance of each one of them. Out of a total of 8, 5 of them measured 'open' on both polarities (infinite resistance) and 3 of them measured anywhere between 10-40 mega Ohms on one of the polarities and close on the reversed polarities.

Do I suspect that 5 of the 8 caps are faulty? and hence not doing any role of filter caps in the PS circuit?

Cheers.
 
Your unloaded 13-14 mA sounds reasonable if you have bleeder resistors. What are the values of the bleeders?

The non infinite resistances are probably due to some residual charge. I measured a PSU that I haven't installed yet, and found similar numbers. I don't think that the caps are bad, but why not measure the unloaded current after installing each cap? That would allow you to verify that none of your caps are leaking excessively.

I guess we're back to a ground loop causing your hum.
 
Your unloaded 13-14 mA sounds reasonable if you have bleeder resistors. What are the values of the bleeders?

The non infinite resistances are probably due to some residual charge. I measured a PSU that I haven't installed yet, and found similar numbers. I don't think that the caps are bad, but why not measure the unloaded current after installing each cap? That would allow you to verify that none of your caps are leaking excessively.

I guess we're back to a ground loop causing your hum.

Cannot find any fault with ground loop. Checked and rechecked. Surprising thing is that, when I change to another PSU PCB with a different set of caps, the hum goes away. Exactly the same wiring and same loops (or no loops).

I am waiting for my new caps to come. I will replace all of them and check, before doing anything else.

Cheers.
 
The transformer also seems to buzz a little bit with this particular PS board. What could be the problem? It has 8 x 15000 uF caps in Pass CRC design. Would a faulty cap create this racket? I bought these Rubycon caps on ebay.

TIA.

It just goes to show you can't trust stuff on ebay.
If you want to buy anything it is usually safer to buy from members in the swap meet or vendor section. After all, when you buy from members (espescially old members) you know you are buying from enthusiasts who love their hobby and often sell stuff as a service to other members as well as being able to buy parts cheaply in bulk for themselves rather than for pure profit reasons.
If you don't have one an LC meter is often a good investment espescially if you are buying caps off ebay.

Is there also any chance the PS PCB is wrongly labelled?
Where did you buy the PS PCB from?
 
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It just goes to show you can't trust stuff on ebay.
If you want to buy anything it is usually safer to buy from members in the swap meet or vendor section. After all, when you buy from members (espescially old members) you know you are buying from enthusiasts who love their hobby and often sell stuff as a service to other members as well as being able to buy parts cheaply in bulk for themselves rather than for pure profit reasons.
If you don't have one an LC meter is often a good investment espescially if you are buying caps off ebay.

Is there also any chance the PS PCB is wrongly labelled?
Where did you buy the PS PCB from?

Yes, I agree about eBay. However my experience with eBay has mostly been very good. eBay and paypal combination ensure enough customer protection, and the seller cannot get away easily. My experience outside eBay has been to the contrary with items getting lost sometimes and seller simply asking me to chase the post office with no protection whatsoever.

Yes, few wrong jfets and these capacitors are the only bad items i might have got through eBay, over 60 purchases.

The PS pcb that I use is from suds who sold here as GB. Nothing wrong with that.

Cheers.
 
Got my shipment of Nippon 15000 uF, 63v caps. Promptly wired them into my existing ps board (4 per rail). No problem or no hum. One channel was picking minor hum through power rail wiring passing close to the toroid. Rerouted the -ve, +ve and 0v wires away from the trafo and the slight hum that was there in one of the channels is gone completely.

Thanks.
 
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