So I am repairing a SMPS in a barco projector and I have this IC that is getting power in but, nothing out. Searching for DPA2A anywhere on the web does not tell me what it is- or who the manufacturer is. I have found some places in China that sell it and they claim that it is made by ON Semi. If you search ON Semi's website, that part number doesn't yield any results. I have attached a photo of it. Any help would be appreciated. Thanks guys.

 

Some photos of the circuit board showing the whole board and some closer views of components around where that part came from may be helpful in at least getting a better idea of what the function of the part might be. Though not unknown, ICs usually are not the problem in non-functional switchers. In modern designs the main switching FET(s) is often the culprit. Bad ("worn out") electrolytic capacitors are also extremely common in switchers.

I suspect all the sellers say it is ON Semi because one said it was and all the rest followed the lead. It might be an ON part with some manufacturer's house number. Most component manufacturers do make an effort to put their logo on parts if at all possible, and SO-8 packages, while not exactly broadsheets, do have a fair bit of space available. Sometimes what is marked is an incomplete part number, but you would likely still have found something plausible in your searching if that were the case.

 

So I am repairing a SMPS in a barco projector and I have this IC that is getting power in but, nothing out. Searching for DPA2A anywhere on the web does not tell me what it is- or who the manufacturer is. I have found some places in China that sell it and they claim that it is made by ON Semi. If you search ON Semi's website, that part number doesn't yield any results. I have attached a photo of it. Any help would be appreciated. Thanks guys.

You're misreading it. I had to blow up your image by 400%. Here's what's written on it:

DPAZA_
PLYW
Jo

 

Nope. Look again. It is clearly 2 not Z.

0.2 pixel gaussian blur, upsampled, contrast enhanced

 

Some photos of the circuit board showing the whole board and some closer views of components around where that part came from may be helpful in at least getting a better idea of what the function of the part might be. Though not unknown, ICs usually are not the problem in non-functional switchers. In modern designs the main switching FET(s) is often the culprit. Bad ("worn out") electrolytic capacitors are also extremely common in switchers.

I suspect all the sellers say it is ON Semi because one said it was and all the rest followed the lead. It might be an ON part with some manufacturer's house number. Most component manufacturers do make an effort to put their logo on parts if at all possible, and SO-8 packages, while not exactly broadsheets, do have a fair bit of space available. Sometimes what is marked is an incomplete part number, but you would likely still have found something plausible in your searching if that were the case.

Thank you for your reply. I have added a couple more photos to help identify what this is. It is U106 on the board.

 

It certainly appears that it is the main switcher control IC.

There appears to be some darkening around Q203, as if it has been burned.

Could you post a photo of the other side of the board? Again, an overall plus one around the region of U106. I'm particularly interested in electrolytic capacitors in that area. C141 may be the only one.

Have you tried to find a schematic for the board?

 

It certainly appears that it is the main switcher control IC.

There appears to be some darkening around Q203, as if it has been burned.

Could you post a photo of the other side of the board? Again, an overall plus one around the region of U106. I'm particularly interested in electrolytic capacitors in that area. C141 may be the only one.

Have you tried to find a schematic for the board?

Yeah the black is from when I first removed q203 to verify it (the glue held it on there pretty well).

I have attached 2 photos; 1 of the other side of the board and 1 of the other side above that IC.

Thank you again for helping me identify this.

 

That's a pretty complex power supply. It looks like it has "active power factor correction" - does it accept "universal input", something like 100 to 240 VAC? Not that it helps identify the part.

I can't find anything at ON that looks like a likely candidate. ON makes lots of switcher controllers in 8-pin packages but nothing I would find with even PA2 in the part number.

One of the switchers on that board will be a "housekeeping' supply to provide standby power for some part of the digital circuitry and probably other parts of the power board. It might be the circuit we're looking at, but it might be the one down at the bottom of the board near the connectors. At that end of the board there are two 4-pin optocouplers across the high-low voltage boundary hatch. To the left of those is what looks like a 1 or 2 watt resistor that looks a bit like one end is quite right. It might be a current sense resistor and sometimes they sort of get blown open like a fuse if a FET fails short-circuit, without actually looking burned. Please have a close look at it. What is marked on the 8-pin DIP IC beside it? (again, not helpful in identifying mystery part, but may have something to do with supply not working).

 

That's a pretty complex power supply. It looks like it has "active power factor correction" - does it accept "universal input", something like 100 to 240 VAC? Not that it helps identify the part.

I can't find anything at ON that looks like a likely candidate. ON makes lots of switcher controllers in 8-pin packages but nothing I would find with even PA2 in the part number.

One of the switchers on that board will be a "housekeeping' supply to provide standby power for some part of the digital circuitry and probably other parts of the power board. It might be the circuit we're looking at, but it might be the one down at the bottom of the board near the connectors. At that end of the board there are two 4-pin optocouplers across the high-low voltage boundary hatch. To the left of those is what looks like a 1 or 2 watt resistor that looks a bit like one end is quite right. It might be a current sense resistor and sometimes they sort of get blown open like a fuse if a FET fails short-circuit, without actually looking burned. Please have a close look at it. What is marked on the 8-pin DIP IC beside it? (again, not helpful in identifying mystery part, but may have something to do with supply not working).

Yeah this little guy powers an 18K Projector. It indeed has active power factor correction. As far as what this supply will accept for mains, it's a single phase 120V only.

I suspect that it may be made by ON but uses an "in-house" Barco part number.

The 3.3V and 5V standby rails are actually the issue with this supply. You are correct that it is in the bottom right corner on the riser pcb. The DIP-8 is an offline current mode controller (ICE3B0365J) which has been verified. I wanted to find the datasheet for this switching ic so that I could verify that circuit as I found the optocoupler (the one by itself in pic 14) faulty. When I get back into the shop tomorrow I will verify those two resistors.

Thanks again!

 

The current sense resistor was indeed open. When you mentioned it, I couldn't remember if I had verified it yet or not. The FET that the mystery ic is running appears to be a little intermittent as well so I'll be replacing both. As far as the mystery ic, I think it's just a PWM ic but, the world may never know lol.

Thank you again for your help.

 

There are so many switcher controllers in 8 pin packages it really is hard to guess what it might be. It does seem to have more than its fair share of passive parts surrounding it and it also looks like it has a discrete transistor output buffer to drive the FET. I think you are right, it is going to have to remain a mystery. It occurs to me that it might have been a sort of "pre-release" part that had a temporary identification marking. I've seen a few things like that in the past.

Hopefully what you've found in terms of known-bad parts will allow you to repair the board. I've fixed lots of switchers by making educated guesses as to what was likely dead, but the complexity of that board doesn't make things easy. At least is isn't built in a way that makes repair next to impossible.

Good luck with it. If you have more questions, don't hesitate to ask. Maybe someone might actually have some useful input.

If you do ever find out what the IC is, please report. Someone else may find this thread in the future and be grateful for the info.