Author Topic: 90's Delta Power Supply Repair (Read 5010 times)

xavier60 · « **Reply #25 on:** July 24, 2021, 06:28:57 am »

Just confirming that the TRIAC has been left out of the auto voltage selector?
Any sign of the TOP222YN being damaged? Between the Drain and Source pins should test like a diode.

Max1636 · « **Reply #26 on:** July 24, 2021, 06:44:11 am »

Yes I removed that triac like you said. I have 155v where the gate terminal would be so that board is trying to turn on the triac I assume. Why would that be? I don’t believe there’s any damage to the TOP222YN as far as I can tell, I have plenty of spares though as I bought 10. I will test it more a bit later. Thanks very much for your help so far I think it’s very close to getting this working.

xavier60 · « **Reply #27 on:** July 24, 2021, 07:30:35 am »

Quote from: Max1636 on July 24, 2021, 06:44:11 am

Yes I removed that triac like you said. I have 155v where the gate terminal would be so that board is trying to turn on the triac I assume. Why would that be? I don’t believe there’s any damage to the TOP222YN as far as I can tell, I have plenty of spares though as I bought 10. I will test it more a bit later. Thanks very much for your help so far I think it’s very close to getting this working.

That 155V likely means nothing, it's about the expected reading between HVDC ground and Neutral.
One possible next action is to apply mains while the TOP222YN is removed with a new R50 fitted.
Another option is to power the Standby PSU board with low voltage, 30V, with all parts fitted.

xavier60 · « **Reply #28 on:** July 24, 2021, 07:41:04 am »

Also check all diodes on the Standby PSU board.

Max1636 · « **Reply #29 on:** July 24, 2021, 12:48:37 pm »

Did some more checking and I’m confident TOP222YN is fine, reads like a diode between drain and source. Couldn’t find any bad diodes on the board. I’m getting 5v DC on the control pin and 16v on the drain pin.. but that was before I removed R50, now I have almost nothing. So somehow R50 was still passing something? Even though I can’t get a reading on my meter… Will have to replace R50 and see what happens as it might of already been bad before.

Do you still think using a 1W resistor from Jaycar would be a bad idea instead of a 0.5W one?

xavier60 · « **Reply #30 on:** July 24, 2021, 01:05:00 pm »

Quote from: Max1636 on July 24, 2021, 12:48:37 pm

Did some more checking and I’m confident TOP222YN is fine, reads like a diode between drain and source. Couldn’t find any bad diodes on the board. I’m getting 5v DC on the control pin and 16v on the drain pin.. but that was before I removed R50, now I have almost nothing. So somehow R50 was still passing something? Even though I can’t get a reading on my meter… Will have to replace R50 and see what happens as it might of already been bad before.

Do you still think using a 1W resistor from Jaycar would be a bad idea instead of a 0.5W one?

You can try the 1W resistor to see what happens. Do you have a variac so that the mains can be increased gradually?

Max1636 · « **Reply #31 on:** July 24, 2021, 01:09:13 pm »

I don’t have a variac unfortunately no, I’ll try a 1W resistor tomorrow and let you know what happens, thanks again for he help.

Max1636 · « **Reply #32 on:** July 25, 2021, 02:31:32 am »

So I’ve added the 1W resistor (In a temporary way because I thought it might blow) and now on both sides of the resistor I have about 330v DC. At the pin I highlighted in the photo I’m actually getting 470v for some reason, does that seem normal? I’m also getting 5.76v from the TOP222YN.

At the top of the transformer which I imagine is the primary side I have the following readings:
1: 330v
2: 330v
3: GND
4: 0v

I don’t seem to have anything from the secondary side.

xavier60 · « **Reply #33 on:** July 25, 2021, 02:51:53 am »

Quote from: Max1636 on July 25, 2021, 02:31:32 am

So I’ve added the 1W resistor (In a temporary way because I thought it might blow) and now on both sides of the resistor I have about 330v DC. At the pin I highlighted in the photo I’m actually getting 470v for some reason, does that seem normal? I’m also getting 5.76v from the TOP222YN.

At the top of the transformer which I imagine is the primary side I have the following readings:
1: 330v
2: 330v
3: GND
4: 0v
I don’t seem to have anything from the secondary side.

If that point is one end of the spike snubber capacitor, then the 470V could be normal. There should be a bleeder resistor across the capacitor, make sure it's ok.
The specs for the TOP222YN says that it self current limits at 0.5A and that's for a brief peak at each switching cycle while at full load, nowhere enough to blow a 1Ω 0.5W resistor. It's a mystery to me.

The presence of the 470v and the 5.76v on the control pin means that the IC is chopping.

Max1636 · « **Reply #34 on:** July 25, 2021, 03:03:04 am »

I’ve highlighted the pin that reads 470v from the other side, doesn’t appear to be a capacitor very close by? Thanks very much for the quick responses.

xavier60 · « **Reply #35 on:** July 25, 2021, 03:12:30 am »

There are 2 brown disc ceramic caps, one is across the HVDC and the other looks to be the snubber.
There should be secondary voltage between the 2 pins that supply the the auto voltage board and the 3rd pin along with respect to HVDC ground.
And also possibly 12V and regulated 5V on the isolated end.

More: How many times have you replaced R50?

Max1636 · « **Reply #36 on:** July 25, 2021, 03:35:45 am »

I just realised I have 4.95v coming out of the standby board! That must of only happened after replacing R50 (Which I’ve only replaced once.) I must not of realised before… I’ll do some more testing and let you know what happens, the PSU might be close to working now.

Max1636 · « **Reply #37 on:** July 25, 2021, 08:03:40 am »

No luck with the server powering on unfortunately. But as I said the standby board is now generating 10v DC which seems odd as I’d expect 12v and 4.95v which is possibly a little low as well.

I think it would be best if I can turn on the PSU without being connected to the rest of the system as it has many micro switches need to be in place and could be faulty. There is a pin on the board labelled ON/OFF, any idea what to do with that pin?

Max1636 · « **Reply #38 on:** July 25, 2021, 08:11:47 am »

So here’s something else. I have 4.95v on the OTP pin on the power supply which you can see in the previous photo. I assume this is over temperature protection?

timenutgoblin · « **Reply #39 on:** July 25, 2021, 08:35:44 am »

Quote from: Max1636 on July 25, 2021, 08:03:40 am

There is a pin on the board labelled ON/OFF, any idea what to do with that pin?

Looking at the photo, those optocouplers might have something to do with OTP and ON/OFF. Maybe ON/OFF is an input and OTP is an output. Try reverse engineering the circuit to figure it out.

xavier60 · « **Reply #40 on:** July 25, 2021, 08:48:32 am »

Normally high may be correct for the OTP.
Not being fully certain of what voltages are supposed to be outputted by the standby PSU makes things tricky.
Measure all of the voltages for now. There might be something damaged near the TOP222YN's Control pin.
There appears to be a transistor there which is odd.

Max1636 · « **Reply #41 on:** July 25, 2021, 09:35:38 am »

These are all the voltages I’m getting at the moment.

Max1636 · « **Reply #42 on:** July 25, 2021, 09:45:22 am »

I can see that one of the optos does OTP, at one point I had continuity and it would change when powering the PSU on and off but now nothing… Not sure what the other 2 do but one of them has continuity. Still 4.95v on the OTP pin.

xavier60 · « **Reply #43 on:** July 25, 2021, 09:57:52 am »

Quote from: Max1636 on July 25, 2021, 09:45:22 am

I can see that one of the optos does OTP, at one point I had continuity and it would change when powering the PSU on and off but now nothing… Not sure what the other 2 do but one of them has continuity. Still 4.95v on the OTP pin.

You will have to research to find the normal state of the OTP.
Did you measure the 160V with respect to Neutral or HVDC ground? If it really is 160V it should be restored back to its normally loaded state by placing a jumper wire between the 2 outer holes of the removed TRIAC although I dont think it matters.
Does the on/off wire have 5V on it like an ATX PSU?

The 13V seems correct for the live side control circuitry.

There is a 25V electrolytic across the auto select PCB's power supply.

Max1636 · « **Reply #44 on:** July 25, 2021, 10:08:47 am »

I’ll see what I can do but as far as I can tell there’s no documentation on the PSU as I have searched. I got that 160v with my negative probe on the HVDC Negative. If I use the Neutral pin with my meter on DC I get 6.7v.

xavier60 · « **Reply #45 on:** July 25, 2021, 10:15:49 am »

Quote from: Max1636 on July 25, 2021, 10:08:47 am

I’ll see what I can do but as far as I can tell there’s no documentation on the PSU as I have searched. I got that 160v with my negative probe on the HVDC Negative. If I use the Neutral pin with my meter on DC I get 6.7v.

The 6.7V is the correct reading and seems low so maybe the 13V is low also. What value is the large resistor on the auto select PCB?
There should be a Zener connected to TOP222YN Control pin. Is it leaky?

Max1636 · « **Reply #46 on:** July 31, 2021, 06:13:14 am »

Check this out! After giving up trying to get information from someone else with this PSU I bit the bullet and connected the 5v Standby pin to the ON/OFF pin and it powered up! The only issue is the 12v rail seems to be very weak which might be why it wasn’t powering up the server it was connected to. I can’t even power up a standard 3.5” hard drive with it, it also only reads about 10.5-11v. I’d say the PSU likely needs a recap?

Max1636 · « **Reply #47 on:** July 31, 2021, 06:25:56 am »

Fairly sure the issue is just caps now as the voltage fluctuates with change in temperature, voltage goes down when applying heat and voltage goes up with freeze spray.

xavier60 · « **Reply #48 on:** July 31, 2021, 06:30:51 am »

I avoid replacing capacitors unless they are known to be faulty.
I don't understand the output topology. The photo in Reply #11 shows a yellow choke with 2 windings on it.
The next 2 yellow chokes to the right have single windings. The 2 small chokes could be saturable inductors to allow independent regulation of rails. See if you can figure out which yellow chokes are involved with which rails.
Also try loading the 5v rail to see how it affects the 12V rail.
Can you check for ripple across the capacitors?

Max1636 · « **Reply #49 on:** July 31, 2021, 07:40:15 am »

Hopefully my scribble is of some help. So it looks like the 12v comes from a different spot than the 3.3/5v rails. There are 2 3-pin chips on heatsinks that I’m yet to identify. Worth noting as well probably that the 3.3v rail is high, it’s more like 3.7v. What do I need to measure capacitor ripple? I will load the 5v rail up with something when I can.

Also I removed and tested the 2 larger caps on the 12v and they both actually test good.


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Author Topic: 90's Delta Power Supply Repair (Read 5010 times)

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