Playstation 2 PSU zener diode values (ZD1 and ZD3)

[Technomancer]

I am attempting to repair a PS2 PSU that died a horrible death when the Q1 mosfet shorted. There are 2 diodes that I believe got taken out along with the main fuse when that mosfet went, ZD1 and ZD3. From the searching/reading I've done on the topic, ZD1 can look like its failed when a continuity check is done in circuit as there is a .25 Ohm resistor in parallel with it. I'll pull ZD1 out of circuit to check it to be sure. ZD3 I'm pretty sure is gone as its showing a 0 voltage drop on my meter in both directions. (Just pulled and checked them both and they are blown).

Does anyone happen to know the values of ZD1 and ZD3? I wasn't able to find a good schematic for any of the power supply variants that I know of (shocker, I know) but there was a forum post of someone who mentioned that they used 18V zener diodes. From my limited knowledge of zener diodes though, there are 2 voltages to consider. The zener voltage and the voltage at which the diode fails (breakdown voltage?). I assume they are referring to the zener voltage in this case.

Any help you can offer would be greatly appreciated.

Here is a link to that thread where the guy said he used 18V diodes for ZD1 and ZD3: https://www.reddit.com/r/consolerepa...ly_for_my_ps2/

Here is the PSU that I have which is slightly different that his (1-468-634-11): https://gbatemp.net/attachments/19-jpg.258976/

[CapLeaker]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

First thing is to upload some high resolution, straight shot pictures of your PSU. Usually the diodes have a marking stamped on it... can you read anything on them?

[Technomancer]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

Looking at the diodes under the microscope, the both have the following markings:
A
TXZ
18

I assume the 18 is the zener voltage. If you still need a closeup of the board, I can probably get that too.

[CapLeaker]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

It's always a good idea to include pictures. A high resolution, straight shot picture can say 1000 words. It also tells the reader what version board.
I guess you answered your own question about the 18V zener diode.

[redwire]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

It would help to know the SMPS IC being used, on the back of the board.
If ZD1 is across a 0.25R sense resistor, no way it's 18V as that's 72A across it before it turns on. Usually there is no zener across such a resistor.

[Technomancer]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

I grabbed a couple of pictures of the board as well as the IC on the back:

Front - https://imageshack.com/i/pnZUUw7nj
Back - https://imageshack.com/i/pnSxqhWUj
IC - https://imageshack.com/i/pnYX7Omyj

[CapLeaker]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

None of those links work for me.

[Technomancer]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

Strange, they work ok for me. Try these instead:
Front - https://imagizer.imageshack.com/img923/6246/ZUUw7n.jpg
Back - https://imagizer.imageshack.com/img923/207/SxqhWU.jpg
IC - https://imagizer.imageshack.com/img923/457/YX7Omy.jpg

[R_J]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

You should attach the photos to your post so they don't disappear like the links do.

The zeners are very likely 18v but there is likely other damage, like the ic.
It is common to have a zener diode across the source resistor, it is there to provide some protection for the CS input of the ic (which is only about 1 volt) but it doesn't always work.

[Per Hansson]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

As R_J said please attach them here instead.
I have attached your pictures to this post.

[redwire]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

I analyzed the circuit enough to figure out those some values. PS2 power supply board 1-468-634-11, Delta ADP-75EP. SMPS IC is DAP002 apparently = ST L5991 pics did work ok for me.

It's usually the small caps C3, C20 that fail Badcaps Sony Phat PlayStation PS2 power supply repair

If the mosfet shorted and failed, then check current-sense resistor R18, if open then ZD1 is dead, check R10 1k if blown then IC might have bought the farm. The mains fuse is supposed to cover for this though.
Mosfet gate-drive: Check R9 20R 1/4W, ZD3, check R11/R15 if cooked then IC might have bought the farm...

ZD1 ?V current-sense resistor R18 clamp (would be 2.7V-5.6V zener, IC max is 6V)
ZD2 15V some overvoltage shutdown
ZD3 18V mosfet-gate drive protection
ZD4 ?V (mains) overvoltage shutdown

C3 33uF 35V (common failed part) SMPS IC power
C20 22uF 50V (replace too) maybe soft-start
R18 0.27R 3W current-sense
R9 20R 1/4W mosfet gate-drive

[momaka]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

And while at it, probably also a good idea to replace the output caps too. Generally speaking, the older Ltec from back then don't seem to fail as much as newer ones... but might as well take that out of the equation too.

[Technomancer]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

I appreciate the help with this one! I'll double check those resistors but I'm pretty sure they all measured ok when I looked at it a week or so ago. Certainly couldn't hurt to replace those caps while I'm at it as well as you suggested. I'll let you know how it goes once I get those components in from Digikey/Mouser.

Sorry about the photos. I didn't realize that I could upload them so I just linked them earlier. A couple of other forums I was on a while ago didn't let you upload things so I had gotten in the habit of just hosting them on ImageShack and linking them. I'll keep that in mind for next time.

[Technomancer]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

Ok, I finally got the parts in for this power supply. As I mentioned before, it needed the 2 15v zener diodes (ZD1 and ZD3), the Q1 MOSFET (K2545), a new main fuse, and the .27 ohm resistor R18 (between ZD1 and ZD3 in the top down picture). I powered up the supply and of course it still has issues. The drain of the Q1 MOSFET is getting 170v, which is good (I think) but the gate pin reads 0v. I checked the R9 (20ohms in circuit), R11 (30.8k ohms in circuit), and R15 (2k ohms in circuit) and they don't appear to be blown. Pin 7 of the DAP002 is 0v when I had it powered on. Is there any other inputs I should check to that IC to know if it's bad or should I just be looking to replace it at this point?

[redwire]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

Pin 8 is power for the SMPS IC and it won't start until over 9-16VDC.
If there is low voltage at pin 8 (same as across C3) I would say the IC has shorted, but there are a few parts like C3 that could be toast but not likely.
It might be hiccuping, trying to start up. I would be using a series light bulb limiter when messing with it.

[CapLeaker]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

That C3 starter cap would be my first guess too.

[Technomancer]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

I did some measuring the morning and saw 11.5v across the C3 cap. I also measured all the pins on the DAP002 and came up with the following:
1: .056v
2: .071v
3: .005v
4: .065v
5: 5.46v
6: .036v
7: 0v
8: 11.5v
9: 11.5v
10: .001v
11: 0v
12: 0v
13: .080v
14: .858v
15: 0v
16: .074v

I can't say I have used a series light bulb limiter before. Is it just a test light that will start flashing if there is intermittent voltage on the line? If so, (and until I get one of those), would any of the test settings on the Brymen 869s catch the voltage pulses in the meantime?

[momaka]

Re: Playstation 2 PSU zener diode values (ZD1 and ZD3)

I did some measuring the morning and saw 11.5v across the C3 cap. I also measured all the pins on the DAP002 and came up with the following:
...

Pin 4 (VREF) - voltage seems way too low. Should be 5V.
Of course, that could be due to voltage on pins VCC/VC is going up and down due to PSU hiccuping (i.e. trying to start.)
Check SMD resistor R6. Also check diodes D2 and D4. If they are good, replace C3. If that has already been done, you can insert about 15-17V DC on pin 8 (VCC) of IC1 through something like a 100-200 Ohm resistor. Before you do that though, make sure you use the series incandescent bulb on the AC of the PSU (see below) and also your voltage source for inserting 15-17V DC must be ungrounded / not ground-referenced (typically 2-prong "wall-warts".) When you insert the voltage, see if pin 4 (VREF) goes to 5V.

I can't say I have used a series light bulb limiter before. Is it just a test light that will start flashing if there is intermittent voltage on the line?

See this:
https://www.badcaps.net/forum/showpo...4&postcount=70

You can use either an incandescent or a halogen light bulb. Must be rated for 120V, obviously (or 220-240V for those who do this in countries with 220-240V AC line.) 40 to 100 Watts rating should do - just make sure you have the PS2 disconnected from the power supply. You cannot use the series incandescent bulb on a PSU that has a load on its output - not unless the bulb has a high enough power rating (several hundred of Watts... or just many bulbs in parallel.)

But anyways, the idea is that if something shorts in the PSU, you won't blow the fuse or any other part, because the bulb will limit the current (and power) going into the device.

Incandescent bulbs are indeed hard to find now... but "decorative" or "appliance" incandescent bulbs should still be easy to find (typically limited to 40 Watts, so grab two and wire them in parallel as if it was one 80 Watt bulb.)