Panasonic switching power supply daughter board has two 27uf @ 50 volt capacitors which I do not keep in stock

[sam_sam_sam]

I did not have any 27uf @ 50 volt capacitors but one nice thing is that it has enough room for two capacitors in parallel a 22uf and a 4.7uf @ 50 volts 22 plus 4.7 equals 26.7uf which so very close to 27uf I will show some pictures of it sometime tomorrow

This is one of the shit est boards I seen in a very long time and it was the daughter board the traces just lifting off the board I had to use the capacitor leads to repair the the traces and the main board is not any better because I had to repair several traces for the daughter board to the main board

After all of that I managed to get the switching power supply working properly again I still have to replace the output capacitors but did not want to do this before I made sure that the daughter board to the main board was working properly or not now that I know that it is working properly I will now replace the output capacitors so I have a power supply for one of my battery testing machine

I am not sure if this switching power supply is medical grade switching power supply it the same company that I have the switching power supply that are but they have a lot better board quality than this one does and the other one does not have a daughter board in it and it does not say Panasonic on the enclosure but the layout is very similar inside of the board so who knows

[stj]

33uf would be my move.
or 47 - depends on what it seems to be for.

[sam_sam_sam]

33uf would be my move.
or 47 - depends on what it seems to be for.

I tried this a couple of times on switching power supplies and things did go very well either it would turn on or it wined really bad so I decided to go that route because of the results that I have seen before

[CapLeaker]

33uf isn’t that common but you should have 47uf in stock, so put either of these in.

[redwire]

You'd have to know what the two caps are doing, if their value is critical or not. Going from 27->33uF is reasonable.
If the cap(s) are part of the SMPS IC power then you'd get a delayed start-up, a few more seconds can get added before the PSU starts up with using bigger parts. I'll go from 22->33uF because they take the ripple current better which is one reason the little caps fail.

What model is this PSU, post pics if it's a crazy Japanese SMPS with Sanken and discrete parts or does it use an IC?
Sometimes manufacturers will use an oddball value like 27uF because they got a good deal on them.

[stj]

27uf +20% for tolerance is 32.4uf
just saying

[sam_sam_sam]

33uf isn't that common but you should have 47uf in stock, so put either of these in.

You are right that it not a common value but it is common in servo drive boards so that is the reason I plenty of them of them if this board quality was not so bad as far as the traces lifting off of the board I would probably would try it and see if it complains about the higher UF value

I also have 39uf @ 50 volts for the same reason they are common in servo drives as well and I have plenty of them as well
I have plenty of the 4.7uf @ 50 volts because some of switching power supplies have this value as well

The main reason I used the two values is because I have them in my capacitor parts bin and because there was p
l of room on the daughter board and because of the way that it was attached to the main board it gave you plenty of room to put them in there that way

[sam_sam_sam]

27uf +20% for tolerance is 32.4uf
just saying

Yes real close to the high limit of the range and like you said it should work with no problem I even consider just using 22uf @ 50 volt ones but this is in the lower range limit but like you I would prefer to go in the higher range limit and not go to the lower range limit

[sam_sam_sam]

You'd have to know what the two caps are doing, if their value is critical or not. Going from 27->33uF is reasonable.
If the cap(s) are part of the SMPS IC power then you'd get a delayed start-up, a few more seconds can get added before the PSU starts up with using bigger parts. I'll go from 22->33uF because they take the ripple current better which is one reason the little caps fail.

What model is this PSU, post pics if it's a crazy Japanese SMPS with Sanken and discrete parts or does it use an IC?
Sometimes manufacturers will use an oddball value like 27uF because they got a good deal on them.

Here are the pictures of the switching power supply in question

[redwire]

I don't see a main PWM control IC in there, but the two 27uF caps might be for the driver stage of a 1/2 bridge, they are to keep imbalance or maybe average current reasonable. They see action when the PSU is heavily loaded.
Never seen a Marcon primary cap before 180uF 400V.

[stj]

marcon are complete crap, i just replaced over 90 of them in a scope.

[redwire]

I know the Marcon paper-in-oil HV caps are crap, used in Leader oscilloscopes. No idea about their electrolytics though, if they are any good. It is an old Japanese brand.

[CapLeaker]

Here are the pictures of the switching power supply in question

Interesting… I am working on a Motorola XPR8300 UHF with intermittent power up. Coincidentally I am in that PSU. Man that thing had a hard life. It lived for like 16 years on top of a commercial wind mill. You wouldn’t believe how much dirt there is in that thing. The fan in the PSU has an open too…
I can’t for my pity lil life not figure out where this thick oil like substance (almost like fluid film or rust check undercoat) come from. It definitely got sucked in and 99% IPA doesn’t really clean it off either. Had to put it into the ultrasonic cleaner for 30 mins and that did the trick.

[stj]

maybe somebody was blasting 3-in-one onto some moving parts in the general vicinity?

[redwire]

Must be ectoplasm
I know I'm in trouble if dishsoap or IPA does nothing, it's not oil then. Then it's acetone or worse I use.
Could be some farm spray, they use pesticides etc. or a windmill spray cleaning solvent or something.

[stj]

does it look like a liquid or just feel like one?
i know the shit they spray out of chemtrail planes feels like powdered teflon because it collects in electrostatic air filters!!!

[redwire]

Maybe the windmill had a tranny leak?

[stj]

wouldnt something like that be at the lowest point for weight reasons?

[redwire]

Wind generators have the prop go into the gearbox right away, they are top heavy.
But I'm not sure what the windmill is all about. Prairies in Canada I only see small ones pumping well water on farms, they are just open-frame steel trusses. No room or radio inside.
It's a prop to right-angle pinion gear then shaft goes down to the ground.

It would be good to know more about the slime on the PC board. I have seen coal dust, cigarette tar and nicotine, grease from a restaurant cooking grill on boards.
Ones from bars/lounges are the worst, it's like booze liqueur goo and girl perfume on the boards lol. I ended up using Fantastik spray on them.
I found ultrasonic cleaning very hard on electronics, it etches solder and busts crystals or IC bonding wires if you are aggressive with it, compared to using the right solvent.

Unless something else leaked and took the piss.

[stj]

the worst is vaporised cola,
some arcade gear will suck spilled drinks into the fans and blast it into the pc unit!!
coin mechanisms are protected from drinks being poured into them with conformal coating, but the motherboards are vulnerable!