Question on a power supply

[nosaj]

Have a power supply out of a electric piano

My question is for the 5 volt regulator having 2 inputs
I want to cobble a transformer to power this circuit, being that it has a 5 volt regulator, just not sure about pins1 2 3
nosaj

[Dave H]

It's a full wave rectifier. It needs a centre tapped transformer winding. Something like 7-0-7 volts should do it (as the input capacitors look to be only rated at 10V). Connect the ends of the winding to 1 and 3 and the centre tap to pin 3.

[nosaj]

It's a full wave rectifier. It needs a centre tapped transformer winding. Something like 7-0-7 volts should do it (as the input capacitors look to be only rated at 10V). Connect the ends of the winding to 1 and 3 and the centre tap to pin 3.

Ok did that getting intermittant DC at the back to back diode thingy( barrier diode?) Says IR81 C4P038 on it. I'm not finding anything on it anyone have suggestions?
I included a pic.

nosaj

[The Dude]

Can you share the entire power supply schematic? It's hard to help without knowing what you're working on. Sans that, it sounds like it's trying to start and then going in to protect- cycling. If that's the case, check secondary supply diodes. Check secondary outputs to ground and see if one of your supply lines is shorted.

[Dave H]

Connect the ends of the winding to 1 and 3 and the centre tap to pin 3.

Typo, that should read centre tap to pin 2

[Dave H]

Ok did that getting intermittant DC at the back to back diode thingy( barrier diode?) Says IR81 C4P038 on it. I'm not finding anything on it anyone have suggestions?

It looks like C4P03Q on the schematic which is a dual Schottky rectifier - C4P03Q.pdf

Where exactly are you measuring?

[nosaj]

Can you share the entire power supply schematic? It's hard to help without knowing what you're working on. Sans that, it sounds like it's trying to start and then going in to protect- cycling. If that's the case, check secondary supply diodes. Check secondary outputs to ground and see if one of your supply lines is shorted.

Sure, Just know this , the amp is in the shop the organ is at the owners house. I have a transformer rigged up to J17 which is connected to pins 1 and 3 and ct'ed to pin2 .
I get no voltage at the fuse. Next step is gonna be just pull out the diode thingy(does anyone know what to call it?) and run solo and see what voltage if any it produces.
Here's a link page 12 is what you want. https://elektrotanya.com/kurzweil_k1...wnload.html#dl
Thanks,
nosaj

[nosaj]

It looks like C4P03Q on the schematic which is a dual Schottky rectifier.
Where exactly are you measuring?

Guess an 8 and a Q are not the same.
Black lead ground pin2 and the other at the fuse.
nosaj

[Dave H]

Guess an 8 and a Q are not the same.
Black lead ground pin2 and the other at the fuse.
nosaj

Looking at the picture it could be a funny Q as it's not the same as the 8 above it.
It should measure DC there. I suppose you've checked the fuse?
Do the diodes measure OK in the C4P03 thingy ? Vf should be lower than silicon. I've attached a data sheet above.

[nosaj]

Looking at the picture it could be a funny Q as it's not the same as the 8 above it.
It should measure DC there. I suppose you've checked the fuse?
Do the diodes measure OK in the C4P03 thingy ? Vf should be lower than silicon. I've attached a data sheet above.

No I've not checked the fuse as the voltage wasn't making it to the fuse, just to be sure I checked both fuse connectors earlier.
On diode test it was measuring about .123 one way and OL the other. The low number was questionable for me, but being schottkey prob ok. But it still isn't passing rectified voltage. On pins 1 I get 12vac pin3 12vac pin2 0 So I'm getting input voltage to c4p03q.

nosaj

[The Dude]

That diode package is just 2 schottky diodes in one package. You should be able to just check them as 2 separate diodes- low resistance one direction and high the other. Is there AC all the way to the diode package (eliminate a connection issue). Is the fuse good? The smoothing cap(s) is/are on the other side of the fuse, so there will be a higher AC content at the diodes with the caps basically disconnected (if the fuse is open).

[nosaj]

That diode package is just 2 schottky diodes in one package. You should be able to just check them as 2 separate diodes- low resistance one direction and high the other. Is there AC all the way to the diode package (eliminate a connection issue). Is the fuse good? The smoothing cap(s) is/are on the other side of the fuse, so there will be a higher AC content at the diodes with the caps basically disconnected (if the fuse is open).

Fuse is good. i used a dc regulated supply about 8v clipped on diode side of fuse holder. Checked voltage at the 5v regulator looks shot also I see 8 volts on all 3 terminals.

Customer complaint was kids were having a hard time getting it to start and would rock the power switch several times to get it to go until it finally stopped responding over a week.

nosaj

[nosaj]

Fuse is good. i used a dc regulated supply about 8v clipped on diode side of fuse holder. Checked voltage at the 5v regulator looks shot also I see 8 volts on all 3 terminals.

Customer complaint was kids were having a hard time getting it to start and would rock the power switch several times to get it to go until it finally stopped responding over a week.

nosaj

Is there an alternative for a 3052v regulator? i could only find 10 pcs for $17 kinda steep.

Thanks,
Jason

[The Dude]

Is there a substantial enough heatsink that you could just use a TO220 5v reg? If so, I don't see why that wouldn't work as long as current capability is at least 2 amps like the original part. You'd probably have to run wires from legs to board, but the basing diagram will be different anyway.

[nosaj]

Is there a substantial enough heatsink that you could just use a TO220 5v reg? If so, I don't see why that wouldn't work as long as current capability is at least 2 amps like the original part. You'd probably have to run wires from legs to board, but the basing diagram will be different anyway.

Not sure how I'd mount it. Here's some pics of board and heatsink. Put an apple phone charger on board for size reference.
nosaj