MVS cabinet power supply (U-SAN) fan question...

[Kujako]

I've noticed that the fan on my power supply isn't spinning. Before I take everything apart looking for faults, anyone know if it's thermally controlled and thus might NOT be intended to spin up? Not having a lot of luck finding docs for it.

 

[YaYaLanD]

Did you try to feed power directly to the fan to see if it’s working?
I don't know if it’s thermally controlled as i don’t own one myself.

 

[Kujako]

Did you try to feed power directly to the fan to see if it’s working?
I don't know if it’s thermally controlled as i don’t own one myself.

Not pulled it yet, going to work on that today.

 

[Kujako]

Did you try to feed power directly to the fan to see if it’s working?
I don't know if it’s thermally controlled as i don’t own one myself.

So... got it opened, and I almost regret it. Somehow a 20+ year old power supply looks really worn out and dirty! Now that it's opened, I can't not clean and refurbish it. Question is, it is worth it VS buying another.

 

[YaYaLanD]

Well, it’s up to you ! I always tend to try to save and refurbish or upcycle.

cleaning is easy, if the PSU is working, why change it ? You can always wire directly the fan to power if there is a broken thermal circuitry... so it will be always on

 

[Kujako]

@YaYaLanD After a bit of cleaning, it looks like it's in fairly good shape all things considered. So refurb it is. Will have to figure out a good way to de-rust the case. Fan does seem to be bad, it works but only if it's "jump started" by spinning it a bit. Then it kicks over fine. Good quality too, very quiet.

 

[YaYaLanD]

What are the specs of the fan ? Is it 12V ? Did you apply 12V to it ?
If both replies are yes, then the fan is dead and should be replaced, if it needs 12v and you applied 12v and it needs “help” to spin —-> dead

 

[Kujako]

What are the specs of the fan ? Is it 12V ? Did you apply 12V to it ?
If both replies are yes, then the fan is dead and should be replaced, if it needs 12v and you applied 12v and it needs “help” to spin —-> dead

Yup, 12v and yes I hooked it up to my workbench power supply. The fan needs to be replaced, easy enough as it's just a 12v 80mm with no tachometer. Sure I have one around here someplace I can use. Just need to figure out how best to clean and de-rust the casing.

 

[trmm]

I don't know if you have CLR on the states, that works pretty good on rust, after you can use some 3M grey finishing pads (scotch brite pads) its recommended you paint the metal parts with enamel paint (from a spray can is quick and easy) and is recommended you recap the power supply, you may have leaky capacitors that are not visible.

 

[Kujako]

I don't know if you have CLR on the states, that works pretty good on rust, after you can use some 3M grey finishing pads (scotch brite pads) its recommended you paint the metal parts with enamel paint (from a spray can is quick and easy) and is recommended you recap the power supply, you may have leaky capacitors that are not visible.

Yeah we have CLR, but given the fairly light amount of rust I'm going to try the "potato and dish soap" method first before anything more drastic. I've thought about applying an enamel paint (Rust-Oleum) but there's no good way to protect the labeling, so that would be a last ditch scenario. I agree re: the capacitors, but that'll have to wait. I don't have the proper ones on hand and ordering single capacitors isn't cost effective (no "recap kits" for this thing out there).

 

[trmm]

I order stuff from Digi key and shipping prices seem fair given its fedex, give it a try they might surprise you, if you have a hot air station you can remove the labels and re apply them later.

 

[Kujako]

I order stuff from Digi key and shipping prices seem fair given its fedex, give it a try they might surprise you, if you have a hot air station you can remove the labels and re apply them later.

I tend to use Mouser, but Digi Key is good as well. Problem is going to be putting together a list of capacitors that I need. Without desoldering them, it's hard to see if the labels can even be read. For the case, I ended up using some 600 grit sandpaper and a hit of brushed nickel finish Rust-Oleum. I left the sides with the labels alone as they were just a bit dirty.

 

[trmm]

Very nice job!

for the values use your phone's camera close to the negative band then review them on your pc I see 2 that might be obstructed though by the dissipator.

 

[Kujako]

Very nice job!

for the values use your phone's camera close to the negative band then review them on your pc I see 2 that might be obstructed though by the dissipator.

There are a fair number of smaller capacitors buried in there around the transformer. But those are also ones I'm more likely to have... so I may just start with the 200v 330s and go from there. Here it is back together, waiting on a replacement fan but I did add a coupling (fan was soldered in). Passed the smoke test, in that it powers on and no smoke came out.

 

[YaYaLanD]

You did a really nice painting job, well done.
Changing all capacitors is a really good thing, it’s cheap and prevents a lot of headaches

 

[Kujako]

Changing all capacitors is a really good thing, it’s cheap and prevents a lot of headaches

100% agree, but that's a bigger project than I'll get to this weekend. Need to start mapping the capacitors and the pinout so I can test it on my workbench. This weekend was all about why the fan wasn't spinning.

Edit: Found a capacitor map!

 

[Kujako]

Follow up: Looks like my 12v is low, which may be the cause of some of my CRT issues. So going in for a full recap. After some hunting around I found a kit. Which is great for the lazy man in me.

 

[Kujako]

Further follow up, after a full re-cap, still seeing under 10v on the 12v rail. So I'm thinking one of the transformers is kaput.

 

[YaYaLanD]

Check the diodes also, a sick one can drop voltage more than usual i read somewhere when troubleshooting a sick PVM PSU

 

[Kujako]

Check the diodes also, a sick one can drop voltage more than usual i read somewhere when troubleshooting a sick PVM PSU

Good suggestion, will take a look. However, for the time being I've ordered a HAPP replacement so I can use my cabinet while I keep working on the power supply rebuild.