YiHuha 853D power supply.

Hope this is in right forum... I couldn't find an "equipment repair" or "bench tools" etc...

Please don't tell me I have a POS and to save my money -- being a student (and paying for it myself) is hard enough... This thing is compact and has worked flawlessly...

I have had this "3-in-1" station for a while now and it's been great. Yesterday the apartment (building-wide) experienced some sort of brown out & surge.

After verifying everything was not broken, we got a list of only a few things that died as a result.

One of them being my 853D 1 amp power supply. The display only rad 0.00 -- and i was putting out exactly that -- no power, volts, current, nada.

I spent the day going over the boards and, of course, found a problem (finally). See image. It appears to be a diode that blew.

If anyone has a schematic or another 853D -- can you help me identify a suitable replacement diode? I have a stash of various diodes, but I'm not an EE guy, so me guessing which one makes me nervous...

Any one have any ideas?

Gotta get a ups for so the brown outs won't screw it (hopefully)

Looks like a plain old signal diode to me, in which case just about any silicon diode (ie, not schottky or an LED) will work.

Unless of course, it was a Zener.

Need to read the numbers on it.

[quote author=Paul__B link=msg=2359631 date=
Need to read the numbers on it.
[/quote]

If I could have read the #'s I would have -- there is typically some glass or something around it -- the cover is missing, it's like the internal guts are now exposed, with everything else gone.

Paul__B:
Unless of course, it was a Zener.

Which would be a 'best try first' -- zener or signal?

Thanks.

OH!

That's not a signal diode! The top is blown off it, and it used to be one of those larger diodes with the black cylindrical case. Probably not a Zener - I've never seen them in that package.

But it could be a schottky...

Try to get it off, and see if you can find any traces of numbers on what's left of the plastic. Also look around in the case and the area where you took it apart and see if you can find the other half of the plastic part

I got it off -- Indeed -- good job spotting it -- I got it off -- one lead just fell away, the other lead was still in the diode. It did indeed blow the top 1/2 off the diode.
I have searched everywhere, it must have fallen out -- I cannot find the other 1/2.

It is a black cylindrical diode with a gray band on top.
The only identifiers left are:
FR2 with an M under the R2 part.

I have a bunch of various (new) diodes and a handful I salvaged out of other things...

A quick search seems to show up as a rectifier 1amp / 600v diode.
the power supply is a 1amp supply -- so, could be right?
I think I have some 3amp diodes: Not that I want to try to pull more power out of it; but would a higher amp diode work (will I damage anything else?)

I tried to get a good picture, but I failed. There is a 2 next to the FR...

diode2.png

yeee ha... (I think)
I have one "FR207" with an "M" directly under the R2.
Physically they are identical.
and: Laugh at me.... I have been working with some (small) SMD boards that lack any notation on the PCB... I didn't even look at the pcb once I removed the diode... Low and behold: FR207!

So I am lucky!
Thanks for your help.

... Now, any chance any of you have an idea where I can get 5v off the boards? I want to drive a more accurate digital ammeter...

Got it all up and running, complete with updated Ammeter for better resolution...
Everything is working great.

I would be a trifle worried that nothing else was damaged.

well; I ran it up to .8 amps and no problems. checked all components and nothing seemed to get excessively hot. While I would like to think I'm more careful, there is the possibilities of either dead-shorting output leads or backfeeding power ...
This thing has been reliable up until this diode burning out.

I don't want to try forcing power backwards or dead-shorting it for fear of doing worse/more damage.

Power coming out is stable & not much noise, so a fluke? a bad diode just waiting to give up? Everyone says these things are built cheaply, so perhaps the cheap diode really wasn't up to the job and wanted an early retirement...