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I had a bug (yes, a literal bug) decide it would be a good idea to crawl inside my printer and short itself across two pins on my printer's power supply board.

I have pulled the board in the hopes of repairing it and I am stuck trying to identify a particular IC so I can replace it.

Could anyone identify the chip and/or suggest an alternative that I could use in place to repair the board?

Printer is a Brother HL-2135W. Board is a Delta EDPS-52BF. Brother part number for the board is LV0848001. I have managed to find a circuit diagram for a very similar board (came from a service manual for the Brother DCP7055 - see below).

Visible markings on the mystery IC are:

DAP?
PVA?
G?

'?' denotes obscured letter/s - unsure how many are obscured.

Images and schematic in link below. Relevant component number is IC31.

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closed as off-topic by Leon Heller, Ricardo, Daniel Grillo, Dave Tweed Aug 24 '15 at 14:35

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the repair of consumer electronics, appliances, or other devices must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired. See also: Is asking on how to fix a faulty circuit on topic?" – Leon Heller, Ricardo, Daniel Grillo, Dave Tweed
If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ Based on those pictures some of the traces of the PCB also got vaporized? D31 looks pretty dead as well. \$\endgroup\$ – Arsenal Aug 20 '15 at 15:53
  • \$\begingroup\$ Yeah did damage some other areas of the board, luckily those are pretty localised and easy to figure out. \$\endgroup\$ – Chris Aug 20 '15 at 16:02
  • \$\begingroup\$ Chances are it's a custom part. Notice they don't provide a parts list in their service manual. This is to keep so-called "unqualified personnel" from servicing it. Just another way to drum up some money. \$\endgroup\$ – DerStrom8 Aug 20 '15 at 16:04
  • \$\begingroup\$ Besides, this question really doesn't have anything to do with electronic design, which is the focus of the EE SE. We do not cover repairs here. \$\endgroup\$ – DerStrom8 Aug 20 '15 at 16:19
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    \$\begingroup\$ @derstrom8: Disagree because OP did the homework and background study as the guidelines ask. \$\endgroup\$ – kabZX Aug 20 '15 at 18:46
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It looks like this is an ONSemi chip from the DAPxxx series. It's a "PWM Current-Mode Controller" and they are all customer specific chips.

Unfortunately you don't know the complete marking but you can probably use the datasheets to determine the version based on the PCA.

But then you need to find some place to get the chip. Maybe you are lucky at a broker.

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  • \$\begingroup\$ You may be right about OnSemi, but i'm skeptical that this is a custom chip. Nealy every manufacturer - TI, OnSemi, Fairchild etc have pin compatible chips for these power supply applications \$\endgroup\$ – kabZX Aug 20 '15 at 20:00
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    \$\begingroup\$ Please see the datasheets of the DAP006: google.nl/url?sa=t&source=web&rct=j&url=http://… first line says customer specific device. All of the DAPxxx datasheets from ONSemi contains these lines. You also cannot find them on the website of ONSemi as they don't show customer specific devices on there website. You agree probably right that there are drop in replacements, but you don't know if all the parameters of the chip are the same. \$\endgroup\$ – rfkortekaas Aug 20 '15 at 20:07
  • \$\begingroup\$ That the datasheet is available is surprising in the first place. \$\endgroup\$ – Passerby Aug 20 '15 at 21:27
  • \$\begingroup\$ @rfkortekaas: You're right about "Customer Specific" but does that mean it is NOT available elsewhere? I did a quick search and came across an ebay link (goo.gl/wO2rCr - Caveat Emptor!). Yes drop in replacement can be a lot of risk for very little gain, hence my suggestion to patch in 24V/3v3 from an external source. \$\endgroup\$ – kabZX Aug 30 '15 at 8:35
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Looking at the circuit and photos, here's my guess:

Power lines L and N come in the top left, then some protection and line filtering is there, which then goes to a bridge rectifier to generate mains rectified DC voltage across C1. If C1 is big (large capacitance), then this is not a UPF circuit since then the frontend is practically just a rectifier.

T1 looks to be a flyback inductor, winding 4-6 is the primary - its got a snubber across it. Winding 1-2 is probably a sense winding, it is used to detect amount of flux in the core. It also seems to be generating some sort of bootstrap voltage across C31. Winding 7-8-9-10-11 is the secondary - the turns have been designed to give 3.3V and 24V. IC1 provides the isolated feedback loop.

I can't see R6 and C34 in your photos, but my guess is that they are there for mains voltage sensing and/or powering the chip at startup.

So: you need to search for
- a switch mode power supply controller chip, 8 pins
- Feedback on pin 2
- Overcurrent detection on pin 3
- Ground on pin4
- Capable of driving MOSFET, gate o/p on pin 5
- Oscillator on pin 6
- Pin 7 unknown
- Pin 8 maybe supply?

Good luck!

Update: Since I happen to have nothing better to do at the moment, I did a little digging on Digikey with the above constraints and the first one that popped out is UCC28600. (datasheet:www.ti.com/lit/ds/symlink/ucc28600.pdf) Having worked in this area briefly I know there are dozens of pin-compatible replacements from a variety of manufacturers, so finding the matching package markings might be near impossible.

However, since your interest is presumably to just get your printer working, you could just desolder the transformer o/p and patch in 24V and 3.3V from a different power supply.

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