Another Deer rebuilt

[Dan81]

As the title says, it's another Deer I rebuilt.

A small set of pictures before the mods. I replaced the AC receptacle as I had a spare one from a defunct Allied. Other than that it was pretty much stock (meaning nothing done to it yet).

What was done:

-Yang Chun 470uF 200v (more like 330uF, and maybe not even that) - replaced with Fuhjyyu LP 470uF 200v ( from a Linkworld, they're at least true 470uF caps)
- added Y cap betweeen primaries
- EE25 choke added in empty spot on PCB
- replaced unsafe Y caps (orange) with safety approved Y caps
- cleaned and lubed the fan (it was full of dirt)
- populated every inductor spot and every PI coil slot
- 1x 1000uF 10V CapXon KM on 5vSB - 2x 1000uF 16v Panny FL (I didn't have any other caps of the same diameter as the CapXon)
- populated all empty cap spots on the secondary with a Samwha RD, a couple of Nichicon PWs and a single KZG (1000uF 16v, it was to replace a 470uF 16v tiny as hell Yang Chun cap near the 12v rectifier)

And that's pretty much all for now. I plan to even out the rails at 20A each and maybe replace the main switchers with 13007s. Not sure if I should replace the heatsinks because they're thick enough (I personally have another Deer on the same platform and that one has paper-thin heatsinks!).

Pictures of the finished rebuild coming soon! I need some sleep right now

[PeteS in CA]

Re: Another Deer rebuilt

Holy cow! Where's the beef?! I think that main output transformer might limit the practical output power capability to around 200W. The output inductor is probably not good for anything close to the rated 5V current; same with respect to what I assume is the 3.3V inductor. Those TO-220 rectifiers look doubtful with regard to the rated 5V and 3.3V currents. But for a 200W PSU, not bad.

I'm going to guess the 5VSB is a "two transistor" design everybody seems to love. If you haven't already, replace all the small electrolytics with PW or LXZ or FL series parts. If you have room and the design skills, add an OVP crowbar circuit at the 5VSB output. That should protect the load should the regulator lose control.

[Dan81]

Re: Another Deer rebuilt

As promised, here are a few shots after the rebuild. The only thing left to do now is replace the load resistors (I might have to ask momaka about that, he knows better than me about these resistors found in Deer PSUs) and replace the secondary rectifiers with 20A parts for each rail.

[Per Hansson]

Re: Another Deer rebuilt

Looks like you did not replace the small capacitors.
If it's a "two transistor" 5VSB design you really should as PeteS in CA said!

[Dan81]

Re: Another Deer rebuilt

You mean those near the two Panny FL on 5vSB? I don't have any replacements for those, unless using 6.3v caps is an option.

[Per Hansson]

Re: Another Deer rebuilt

The smaller caps between the transformers, I count 5x of them.
There is also one by the supervisor chip
They will be rated around 35v to 63v and around 22uF or maybe less.
https://www.badcaps.net/forum/attach...3&d=1510988520

[Dan81]

Re: Another Deer rebuilt

In that case, I don't have any replacement on hand. I could get some Samwha RD caps but not sure if they're good for the purpose, since they're GP from what I've heard. I could be wrong though.

[Per Hansson]

Re: Another Deer rebuilt

Just look up the datasheets of whatever is installed there now.

[momaka]

Re: Another Deer rebuilt

As the title says, it's another Deer I rebuilt.

Hmmm... now that looks awfully familiar. Wait a minute! I know why - it's the same PSU I posted about eons ago here:
https://www.badcaps.net/forum/showpo...&postcount=491

A small set of pictures before the mods.

YAY! You're finally taking nice pictures for us.

- 1x 1000uF 10V CapXon KM on 5vSB - 2x 1000uF 16v Panny FL

GOOD. As it's a flyback design, these ultra-low ESR caps are actually not a bad idea. Should keep the 5VSB circuit happy... if you also replaced the critical cap, C8 that is (by the mains fuse). IIRC, that should be either a 50V/22uF cap, 50V/47uF, or 25V/47uF.

If you don't have a proper replacement low-ESR cap for it, then you can just add another small cap with it in parallel, just in case (like 1-4.7 uF). I actually tried adding a 4.7 uF ceramic SMD cap in parallel with the critical cap in another Deer, and it didn't seem to have any adverse effects. But I do need to do more testing on that. I want to see what happens if I remove the electrolytic cap and run the 5VSB just with the 4.7 uF ceramic cap.

Another idea is, you can use several 4.7-10 uF caps in parallel (the number will depend on the capacity you're trying to achieve) to replace that critical cap. This will give you lower ESR and also redundancy - if one of the caps fails, you will still have at least another one still working.

Judging by how darkened the area looks around your 5VSB circuit, you really should do something about the critical cap C8.

In that case, I don't have any replacement on hand. I could get some Samwha RD caps but not sure if they're good for the purpose, since they're GP from what I've heard. I could be wrong though.

If they are not rated for at least 105C, then don't bother. That part of the 5VSB circuit runs on the very warm side, and 85C caps may not last too long.

Not sure if I should replace the heatsinks because they're thick enough

They're thick enough indeed, but they don't have that much surface area. And I'm not sure how (in)efficient this PSU is, but I wouldn't be surprised if it's somewhere in the low 70's for the most part. With that said, personally I wouldn't bother replacing the heatsinks, unless you will be drawing over 120-130 Watts DC power from the PSU. I don't suggest pushing it over 200 Watts, as that is probably the maximum continuous (long-term safe) DC power you can draw from this.

Holy cow! Where's the beef?!

It's a Deer, so naturally... no beef for you today, sir.
But if you like Deer meat... that's been hit and rotting on the side of the road for months, this PSU has that.

I'm going to guess the 5VSB is a "two transistor" design everybody seems to love.

And I will confirm that guess.

As promised, here are a few shots after the rebuild. The only thing left to do now is replace the load resistors (I might have to ask momaka about that, he knows better than me about these resistors found in Deer PSUs)

Ask, and you shall be answered.
Actually, I am no expert when it comes to the load resistors. I just "try things" and see what works.

Now, the interesting part is, when I posted about my same PSU above, I mentioned that I would fix/mod it sometime in the future... and I did. But for some reason, I never posted about it or what I did (nor did I take notes of what I changed, which is strange because I always do). But I did take some pictures. And going by those, it looks like one of the very first few things I did was to remove the minimum load resistor on the 3.3V rail, which I believe is R49 - a big 6.8-Ohm resistor rated for what appears to be 3 Watts. I replaced it with a 30-Ohm resistor (3x 10 Ohm resistor in series, as they were tiny 1/4 Watt ones). I don't remember what the 5V rail had for the load resistor, but looking at your pictures, it appears to be 100 Ohms (R61 or R67?), which is fine. Looking at the pictures I took of my modified unit, I left that resistor in there as well, so mine was probably the same as yours.
Finally, the 12V rail load resistor is between the 12V rail PI coil, 12V rail output filter cap, and 12V rail wires. I can't quite see what I did with mine from my pictures, but looks like I either removed it altogether (probably because I didn't have anything suitable). But typically I recommend 330 to 1000 Ohms, 1/2 Watt or higher rated (1 Watt if under 470 Ohms).

Otherwise, I did pretty similar mods to you - added most of the missing PI coils (save for the -5V and -12V rails), and populated the empty cap spots with more YC caps from another similar gutless L&C (posted in the same thread as the above PSUs, right just under that post). I never planned on using that PSU in a computer, but I fixed it just in case I really needed something and didn't have anything else better over in that house. After all, I'm sure my modded L&C is better than a stock new one.