New power supply doesn't power on

thatoneguy

Joined Feb 19, 2009
6,359
Got a new power supply, a PicKit 2 with low pin count demo board, and I suspect Santa is bringing me a new Digital Multimeter.
You are set!

Hope Santa brings you the Fluke 87 Ex (New one after the 87-V), but an 87-V is good enough to forego needing a scope at lower frequencies (for me anyway)

On the power supply, Does that board that broke have a heavy transformer on it and the board not anchored well? I'm trying to think how it flexed that much. Good thing the whole PCB didn't crack instead!
 

Thread Starter

ke5nnt

Joined Mar 1, 2009
384
You are set!

Hope Santa brings you the Fluke 87 Ex (New one after the 87-V), but an 87-V is good enough to forego needing a scope at lower frequencies (for me anyway)

On the power supply, Does that board that broke have a heavy transformer on it and the board not anchored well? I'm trying to think how it flexed that much. Good thing the whole PCB didn't crack instead!
It's a small board that doesn't have anything on it but the power switch, 2 jumpers and some capacitors. I'm almost certain that the jumper that broke wasn't fully seated when it got soldered. Any significant force applied on it would have pushed the jumper the rest of the way into the PCB through-holes, and with the mechanical attachment of the solder, lifted the PCB traces off the board causing them to break.

Quite honestly, if the whole PCB had snapped in half, it would have been easy to build a whole new one from scratch. As far as damages that could happen when something like a power supply gets dropped, I believe I got lucky. It was an easy fix. The shipper could have done a much better job of packing the thing. It was put in a plastic bag, dropped in a box, and filled with packing peanuts. Not quite adequate enough for something like this I'm afraid. You should see the box it came in.

I am grateful that I was able to locate the problem and get it fixed without much issue. I got back with the seller and explained the problem and that I had fixed it. I offered him a slightly reduced price which he accepted so I'm still happy with my purchase. I think when you start going to school for electronics engineering and get to work in the labs at school, you really get spoiled on good equipment.
 

thatoneguy

Joined Feb 19, 2009
6,359
I I think when you start going to school for electronics engineering and get to work in the labs at school, you really get spoiled on good equipment.
Yeah, there's a bit of a shock, but once you establish a career as an EE, you often get a lab set to use at home, which in some cases makes the college stuff look like ancient tech as far as scopes go. The sheer amount of test equipment that is held for a year if it hasn't been calibrated, then sold as surplus is mind boggling. Pity they don't sell them as singles, just palletes full, which is where testequipment.com and other places get their "new, calibrated, slightly worn" inventory.
 

spinnaker

Joined Oct 29, 2009
7,835
Yeah, there's a bit of a shock, but once you establish a career as an EE, you often get a lab set to use at home, which in some cases makes the college stuff look like ancient tech as far as scopes go. The sheer amount of test equipment that is held for a year if it hasn't been calibrated, then sold as surplus is mind boggling. Pity they don't sell them as singles, just palletes full, which is where testequipment.com and other places get their "new, calibrated, slightly worn" inventory.
What's with that website? You have to register just to see what they have in inventory?
 

dick56

Joined Apr 27, 2011
30
I have two of these power supplies and use them as constant current battery chargers for aircraft batteries. They work fine but are not protected well for cross connecting the output. If you contact Sean at Mastech, he will email you a three page schematic which basically covers the power supply part and a little of the readout part. I was able to find a problem with the schematic. They put a 1N5412 diode across the postive and negative outputs for protection and it blew. What your pics seems to show is two of the bridge diodes are separated from PCB. That is probably enough to shut down the whole supply.
 

Thread Starter

ke5nnt

Joined Mar 1, 2009
384
What your pics seems to show is two of the bridge diodes are separated from PCB.
What pictures are you looking at? My pictures show a single 4-pin jumper which separated from the PCB on the power switch board, nothing close to the bridge. I moved the jumper to the empty location and presto, everything's working fine.

Thanks for your input though, and welcome to the AAC community.
 

R!f@@

Joined Apr 2, 2009
9,734
I have two of these power supplies and use them as constant current battery chargers for aircraft batteries. They work fine but are not protected well for cross connecting the output. If you contact Sean at Mastech, he will email you a three page schematic which basically covers the power supply part and a little of the readout part. I was able to find a problem with the schematic. They put a 1N5412 diode across the postive and negative outputs for protection and it blew. What your pics seems to show is two of the bridge diodes are separated from PCB. That is probably enough to shut down the whole supply.
Can I have the schematic please. :p
 

Jotto

Joined Apr 1, 2011
151
You are set!

Hope Santa brings you the Fluke 87 Ex (New one after the 87-V), but an 87-V is good enough to forego needing a scope at lower frequencies (for me anyway)

On the power supply, Does that board that broke have a heavy transformer on it and the board not anchored well? I'm trying to think how it flexed that much. Good thing the whole PCB didn't crack instead!
Its a great meter, I like mine. I like the change that diode check doesn't need to push a button to activate. Price was a bit high, but well worth the added expense.
 

Wendy

Joined Mar 24, 2008
22,141
I always insure my USPS packages, but don't bother with delivery confirmation. One is enough.

Nice job on the power supply, BTW. It looks good.
 

thatoneguy

Joined Feb 19, 2009
6,359
Its a great meter, I like mine. I like the change that diode check doesn't need to push a button to activate. Price was a bit high, but well worth the added expense.
I like that it will check any color/power of LED on diode check which goes to a high voltage, which also lets you ID the color of one that you re-located after being dropped a month prior. :D

And the Low Pass filter, and the very short peak capture, and the instant bargraph that gives you the value faster than the digits, and, well, everything about it! Purchases I will never regret.
 
Top