Can we id this transformer?

[dka56]

From a B&K Ref 50, I might recap the power supply circuit....but want to start here. Not sure the make but here's the pic.

I'm looking to at least get a schematic of the transformer or find out what each wire does. I'm new to diagnosing circuits but im good with a soldering gun.....

I have an increased amount of hiss from the tweeters and a very small amount of hum from the mids. May be a ground issue but either way, it's roughly 17 years old so it wouldn't hurt to check it out.

 

[cademan]

Just take a volt meter and see what the voltages are on the secondary windings.

Your transformer is NOT the cause of hiss or hum. Please don't guess on the diagnosis or you will have more problems than what you started with.

FYI, I am using amps and receivers over 60 years old with original transformers. If it is not shorted or smoking or blowing fuses, ignore the power transformer and look somewhere else in the circuitry for the hum & hiss.

Hiss is usually due to off resistors and/or noisy rectifiers/diodes.

Hum is usually bad capacitors except for ground loop hum.

 

[dka56]

Thanks...I should have been more clear on my intentions with the transformer.

I'm not sure what the voltages should be, mainly wanted to verify. I will check the above mentioned, likely change the caps mainly due to age.

 

[tarior]

Don't overthink things, man. Like cademan said, if it's not smoldering or blowing fuses, there really isn't anything to check or double check when it comes to the transformer. It's safe to make the assumption that it is functioning correctly.
Hum and hiss developing could be a few different things, including in your head (no offense meant), or more noticeable after getting more sensitive speakers, or a sign of component degradation, grounding issues, or a combination of all the above.

 

[Bob]

or trace the leads back to a solder joint. wires that go to a switch then the AC power input line
OR to the power supply circuit. that's if your picture is accurate in only showing 4 wires.
stop and go no further if there are other wires not shown (other side or underneath).

or use insulated probes on each of the set identified as to power supply then clip on these,
switch VOM/DMM to appropriate voltage setting, then turn on power. record.

then do the same for the other set of wires. record.

you will now have the "test" specs. verify twice. once against schematic and if not noted
then work backwards from power supply to arrive at voltage input to PS which should
be identical to AC output of transformer. second test is look up transformer in parts list,
must match stenciling on transformer AND lookup specs on the web. again, verify all three
are identical - if not do not touch. one wrong change can turn unit into (inedible) toast.

this test (5 minutes with bio, smoke, breaks) and 30 minutes for the paper chase.

 

[dka56]

I was unable to find the specs for the transformer, and I agree, the issue is very likely elsewhere, if not absolutely. Perhaps the caps but I only wanted to verify the voltages it I did get them recorded.

Top to bottom:

White: Mains neutral
Yellow: 121.8 VAC
Orange: 220.6 VAC
Red: 240.4 VAC

Top to bottom:

Purple: 2.71 VAC.......... Blue: 24.65 VAC
Black: 185.3 mVAC......Gray: 16.22 VAC
Purple: 2.73 VAC...........Gray: 16.22 VAC
Brown: 4.68 VAC...........Blue: 24.68 VAC
Brown: 4.68 VAC

 

[century tek]

Voltages don't look out of the ordinary, and they really don't mean anything in this particular circumstance as your problem has absolutely nothing to do with the power transformer.

If its coming through both channels, any hum is most likely caused by a bad capacitor in the power supply.

Hiss can either be out-of-tolerance resistors, or noisy (hissy) diodes.

17 year old unit is just a child.