killed my power supply, any ideas on how to fix? (Full Version)

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cwharper -> killed my power supply, any ideas on how to fix? (9/2/2007 4:04:12 AM)

Power supply is the Mastech hy5020e, it has been working just fine for charging A123 cells and I've also been using it to charge the deep cycle battery. When it died, it was maintaining 13.2v and 0.1 amp to the deep cycle battery. I was not home when it died, but when I did come home it was dead. Now, it won't turn on, no noise, no fan, just nothing, not even a burnt smell, and no output from the terminals either. While I was gone there was some bad weather.

Do any electronic guys out there know what might have happened to it?



backyard.basher -> RE: killed my power supply, any ideas on how to fix? (9/2/2007 4:11:05 AM)


quote:

ORIGINAL: cwharper

Power supply is the Mastech hy5020e, it has been working just fine for charging A123 cells and I've also been using it to charge the deep cycle battery. When it died, it was maintaining 13.2v and 0.1 amp to the deep cycle battery. I was not home when it died, but when I did come home it was dead. Now, it won't turn on, no noise, no fan, just nothing, not even a burnt smell, and no output from the terminals either. While I was gone there was some bad weather.

Do any electronic guys out there know what might have happened to it?



Sounds to me like you might have blown a fuse.. Pop it apart and have a look inside and see if you can spot a fuse inside it. Just try not to touch anything.. depending on how long ist been sitting things like that can hold voltage for a while andf you might kill yourself if you go fingering around in it. If its a fuse you should just be able to pop it out and pop a new one in no problem.



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/2/2007 4:52:32 AM)

I have opened it up and had a good look around already. I don't see any sign of a fuse. Yes I am aware of the lethal voltage present in a power supply plugged in or not. With the supply plugged in and using a fluke multimeter I have identified where the AC is initially fed to the board. Then, with the on/off switch to on, there is 340v dc present across what looks like a capacitor on a modular circuit plugged into the main board containing a small transformer. On this same board, at different terminals there is regular 120v ac present. I'm guessing the transformer is stepping up the voltage and then a diode is converting it to dc with the capacitor filtering out the ripples. From this a wire of about 16 to 18ga is leading to what looks like a mosfet and the other two connectors of the mosfet (about the size of a dime) have 12ga wire leading back to the main board. These two wire have nothing across them, but they each have 340v dc back to the wire from transformer. The 340v disappears with the on/off switch turned off.

What I was hoping to find is a single burned out component to replace, but testing components installed in a circuit is just about impossible with collateral flows around the components.



mrasmm -> RE: killed my power supply, any ideas on how to fix? (9/2/2007 4:56:53 AM)

just incase you might not know what you are looking for here is a pic

the circle is the fuse, and the X's are what you want to avoid that can shock you



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/3/2007 1:55:18 PM)


quote:

ORIGINAL: mrasmm

just incase you might not know what you are looking for here is a pic

the circle is the fuse, and the X's are what you want to avoid that can shock you


No, I don't see anything that resembles any fuse I've ever seen.



backyard.basher -> RE: killed my power supply, any ideas on how to fix? (9/3/2007 3:45:45 PM)

Any way you can take a pic of the inside so we can see??



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/3/2007 5:59:33 PM)

I really appreciate your willingness to help. Pictures are not a problem, and I can take more if needed. Here are some pics of the innards.

First pic, front of unit
Second pic, left side of unit where 120v ac comes in, univeral plug on bottom and voltage selector on top (it is on 115v), mains goes to switch on front of unit then to back again where it connects to main board (see last pic). When switch is on this is hot with 120v ac
Third pic, on/off switch to far right bottom, the standing up board is modular and can be removed, the thing with only red and black wires, is attached to the removeable circuit and reads 0.1 ohms with it disconnected from the circuit. This modular board has one IC chip which I cannot identify, it has 4 legs.
Fourth pic, different angle of pic2
Fifth pic, top view, front of unit to right and back to left.
Sixth pic, right side of unit, the two other standing up circuits are removeable as well, and they contain IC chips (14 legs) which I cannot identify.
Last pic, bottom of unit, on/off switch to top, right, ac mains to top, left.



backyard.basher -> RE: killed my power supply, any ideas on how to fix? (9/3/2007 7:04:23 PM)

Man thats a nice looking power supply... I didnt see anything that looked like a switch either. What about under any of the boards?? I have not ever seen a device like a power supply that didnt have some sort of a fuse for protection. I have an old pc power supply I converted to run my battery chargers and it has a fuse in it.



Andrew -> RE: killed my power supply, any ideas on how to fix? (9/3/2007 7:54:19 PM)

Unfortunately, trouble shooting a PSU without a schematic is almost impossible. Starting points are searching for any discoloration (dark spots due to heat) on the circuit boards and on all the components. Even if you can find a burned component, it's failure can be due to another less obvious failed component farther up the circuit path.

Occasionally, you can have a cold solder joint open up. While this may seem bazaar, place the PSU in the fridge for an hour to cool it down and see if it restarts. The downside to this is condensation -- you will need to keep it under a good airflow until it returns to room temp. If it does restart, then it may be a bad joint. I'm not optimistic that this is the case since it has functioned for some time at operating temperature.

I have replaced a number of fuses in PSU's, but in the vast majority of cases, the fuse has blown almost immediately due to an internal short. These were computer PSU's and were simply tossed rather than spend time searching for the problem.

Since yours is a rather expensive PSU, your best bet is to have it serviced by a qualified technician.Tanic Packs carries this power supply -- you might contact them about service or locating a service center. Warranty is listed for a year.

Generally in products of this type, repair involves complete board replacement rather than component troubleshooting -- it's usually cheaper in the long run.



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/4/2007 12:36:36 AM)

Crawl n clod, Correction, it "was" a nice power supply, now it's a door stop. I've converted a couple of atx ps to run chargers and saw the fuses in there also, the only place I haven't looked yet is behind the lcd display because it looks the toughest to get to.

Andrew, I'll try the fridge test. And I was afraid that modular replacement is the method of choice for repair.

After I've thought about it some more two possible causes that could have occured are backfeed from the battery if the utility power blinked or went out while I was gone and/or a lightening surge damaged something.

I've already ordered another ps identical to this one, and will install a 25 amp 50v diode on the positive leg to the battery to make darn sure feedback doesn't occur again and just compensate for the voltage loss with the ps. Seeing just how sensitive it is, I will power the whole thing through an UPS with surge suppression and battery backup.

Does this added level of protection seem adequate or is there something else I can do to protect it?

And then after the warranty runs out I might open the working one up, measure voltages, and compare with the old one.




Flying Geezer -> RE: killed my power supply, any ideas on how to fix? (9/4/2007 1:51:39 AM)

It probably as a varistor that cuts off power when it exceeds X amount of current near the input. The problem could be as simple as a 10 cent transistor that has failed in the voltage regulator circuit.

If you can get a circuit diagram, a local ham or t.v. repairman can probably fix it for much of nothing.



Probedude -> RE: killed my power supply, any ideas on how to fix? (9/4/2007 4:21:34 AM)

The fuse is located in the housing that accepts the AC power cord. Look at it carefully - you can pop it open to reveal a fuse from the outside of the unit.

Dave



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/4/2007 5:08:01 AM)

Thanks, I found the fuse in the ac receptacle, however it is not blown. Ohm meter confirmed visual inspection.



Probedude -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 1:34:02 AM)

That bank of electrolytics right after the 3A diodes should be at a pretty high voltage when plugged into the mains. See if you're getting voltage there.

Is there a PWM IC driving the primary mosfet? If so, what's the pn?



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 2:24:15 AM)

The bank of 4 electrolytes have 166v dc across each. The pics are of the modular board next to the electrolytes. The 4 legged IC has this part number C4U9, PCB17, Sharp. You can just about see it in the pic. The other thing that looks like a small mosfet in a heat sink has this part number, H451, TOP223Y, 32034A, PHIL. The green wire is attached to the wire from the transformer.

Is the other big brown shiny thing a MOV used in surge suppression? It has 340v dc across it.

I could be reading PCB17 wrong, the "B" could be an "8" letter vs number or PC817.



decay -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 2:42:47 AM)

The photos in post 7 ,show a round device mounted to the heat sink.
This should be a thermal fuse, check it for condinuity.



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 3:25:27 AM)

The thermal fuse has condinuity, 0.1 ohms.



gene webber -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 3:51:11 AM)

OK CW, when you ordered a new Mastech 5020 did you ask them if they could repair your fried unit? Just curious, because I am looking at this critter if I go with 10-12s packs in the future and if there is no support for it I may have to reconsider my options.

Thanks..

Gene



Probedude -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 5:51:18 AM)


quote:

ORIGINAL: cwharper

The bank of 4 electrolytes have 166v dc across each. The pics are of the modular board next to the electrolytes. The 4 legged IC has this part number C4U9, PCB17, Sharp. You can just about see it in the pic. The other thing that looks like a small mosfet in a heat sink has this part number, H451, TOP223Y, 32034A, PHIL. The green wire is attached to the wire from the transformer.

Is the other big brown shiny thing a MOV used in surge suppression? It has 340v dc across it.

I could be reading PCB17 wrong, the "B" could be an "8" letter vs number or PC817.


4 legged part is an optoisolator - used in the feedback circuit for regulation.
I don't see enough 'smarts' on that board and the transformer is too small to be the one that is supplying your main output power, probably just used to power the front panel meters and control circuitry. The smarts must be off this board and coming from somewhere else.

Big brown thing is a polyester cap used probably as a snubber to protect the mosfet.



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 1:28:33 PM)

I called acifica and spoke with someone who said he would research the problem and get back with me. I also sent an email to them. Not enough time has passed to know for sure about their support, but another person on this board said he was able to fix his with their help. Since we suspect lightening surge or backfeed that's not covered in the warranty. Most of my problems is of my own fault and ignorance.



gene webber -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 5:59:26 PM)

Thanks for the reply CW, I sent an Email to Acifica asking about their warranty and nonwarranty repair capabilities, parts availibilty and repair turn around times. I have not heard back yet, but will report to the forum when I have a response.

CW,I know you think mother nature killed your Mastech, but it should be repairable, whether a board or some other component needs replacement. My concern at this time is the Mastech method of charging A123 batteries is relatively new and how the company will support their product. I just had a computer printer die on me and repairs are possible, but at what cost? It's not like these power supplies are only $19.95 (as seen on TV) and if it doesn't work as advertised or breaks easily you throw it in the recycle bin and move on.

Shouldn't the fuse blow if you have a power surge caused by a lightning strike? I'm not well versed on electrical grid anomalies and their effects on electronic devices. Maybe someone here on this forum could enlighten us.

Anyway CW, keep us informed, some of us are watching and listening with great interest.

Gene



gene webber -> RE: killed my power supply, any ideas on how to fix? (9/6/2007 8:51:51 PM)

OK, here's Acifica's response to my email. I sent it on 9/5/07 about 9:00pm PDT and received reply 9/6/07 at approx. 10:00am PDT.

Hello,
Thanks for your note, please see my answers below:

Do you have the ability to perform warranty and non-warranty repairs in house?-- We provide warranty service for all the power supplies we sell.

Do you have parts available for repairs?-- We keep some parts around.

What kind of turn around times are common?-- Within a few days.

Best regards,

Sean
Acifica Inc.- Innovative products at compelling price.



That is a very fast response in my book. Sounds like they are on the ball. There may be hope CW....


Gene



cwharper -> RE: killed my power supply, any ideas on how to fix? (9/28/2007 1:48:50 PM)

Update: Acifica has been very responsive. I now have a circuit diagram or schematic for the HY5020E.



jrb1 -> RE: killed my power supply, any ideas on how to fix? (1/2/2008 7:14:39 PM)

Hi CW!

I too have exchanged an e-mail with Sean.

I'm trying to get a handle on the in-rush current so I can reliably run my MasTech off of an Inverter when AC in not available. He didn't have an answere annds seemed just a bit confused; sent hime soem more info so maybe I'll get a better reply shortly.

Been googling trying to learn more and found this; do you think it could be done/help us?

Also, here's a shot of my EQC (converted H9) fly it via A123-10S2P (or 1P).

TIA,

Jim



jrb1 -> RE: killed my power supply, any ideas on how to fix? (1/2/2008 8:13:40 PM)

Maybe something like this could be easily added between the Inverter and MasTech: http://www.ametherm.com/Inrush_Current/welcome.html ?



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