EEVblog #755 - Fluke PM2812 PSU Ebay Score

Dave checks out a Fluke/Philips PM2812 System DC Power supply he scored from ebay for 30 bucks.
Does it work?
Will the bunker hardware tin collection come through?
Or will it just be couch feet?
Forum:

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[sbalogh]

"winner, winner... chicken dinner". I am so glad you said that. I completely forgot I had some chicken defrosting on the kitchen sink. By the time I got to the end of your video, I began to detect delicious smells coming from the kitchen.

[ebenjamin]

Front binding posts were an option for these power supplies (I have 2 single channel units and one dual channel unit with this feature). It is a metal section that attaches to the underside of the main unit using 7/8" stand offs with screws that pass through the feet. The lower section consists of 5 posts (Chassis GND, V-, S-, S+, V+) and a sense switch (local or remote). It is electrically connected to the main unit via 4 wires that run inside the lower section and attaches to the terminal block on the rear of the main unit using common spade terminals. In order for the binding post section to function without throwing a FAIL error, there is a jumper on the power output board that needs to be in the OFF position to disable the onboard capacitor between the V+ and V- output terminals; this is necessary because there is a capacitor already incorporated in the binding post section. Below is a link for the user manual.

[MTTT-bluo]

I does look like those capacitors are in fact in series. The jumper when set to the 110V closes the circuit between one leg of the AC side of the rectifier bridge and the center connection of the series connected capacitors. This acts like a voltage doubler circuit. The 220V terminal with no trace is essentially a park position for the jumper. When it is open, the circuit does not act as a voltage doubler and is thus ready to accept 220V.

The exact same configuration has been used for decades in typical computer switching power supplies. That is what the voltage selector switch does on those computer power supplies.

[iamthejohn]

Dear Dave. Thanks for inspiring me. My recent ebay score (down to you) a "faulty" kenwood 5.1 receiver was just easily fixed by replacing the batteries in the remote. Happy days. Thanks again, John

[aisotton]

You could make an acrylic case so you can see inside while it's running. Acrylic sheets are pretty easy to glue and drill. If you still have your intern he should have access to a laser cutter at university :-)

[WestCoastMole]

Dave regarding the wooden case I would recommend you first pull out your Spectrum Analyzer and check what is radiating from the innards first.Switching Power Supplies were of variable quality in that era and known for being noisy. And wooden case will give you nothing in the way of shielding. Do you really want a Hash Generator in your lab ?

[jameslmorehead]

Darn.  I was hoping for more of a repair video.  Even after taking 2 years of technical school, I learn more from you videos than I did there.  You rock Dave!

[klightspeed]

The 110V/220V jumper may be like the 110V/220V switch on older AT/ATX power supplies, which simply connects the centre-tap of the input capacitors to neutral when on the 110V setting. Edit: I see MTTT3000 beat me to it.

[BigManko]

We need an "MORE COUCH FEET!" T-Shirt.

[xDRTeK]

Dave, good idea about the problem of hoarding items just for the sake of future use.
The mess is always not a good alternative to going out and buying them when you need them. Just for the sake of time wasted is time lost and can't get back and that is not worrying about the mess and dust accumulating around junk that is not going to be  needed or used anytime in the near future.

[ckm-mkc]

I have one of these - the backlight burns out on the display - it's an EL backlight that you can easily fix.

[jacobluechtefeld]

Dear Dave, I love what you do on the EEVblog and I am a huge fan of yours! I first found you about a year ago or so and I am always checking your posts here. I am bidding on an Agilent 6653A and it started out at 9.99 usd and has a shipping price of a whopping 55.63 usd on it. I did my max bids and hope I win as my cheapo bench power supply so called a Lab ready grade psu is complete garbage and I paid for it brand new a cost of 48.98 again USD and it is the chap ass course and fine knob type. I really do making and all kinds of this type work as an advanced hobbyist and thought why not go for the bidding since it is in the price I was wanting to spend anyway. Here is the thing on why it is so cheap. It is sold as is for parts or repair because seller has no good enough way of testing it and they told me in the ad it does power up and does things when buttons are pressed but not tested with loads or other types of tests. I am wanting this type of psu as I hate turning knobs and would rather punch number keys and have it do the adjustment that way. Also Sir, What is you're Shipping info? I have some things I hope to send you and I would like to know if we can be mail buddys or pin pals? Anyhow I gotta get back to cleaning up and hope this message gets to you.

You'r friend and huge fan in electronics
-Jake L.

[ElmerFuddGun]

4:37 "... ah ha, I should have thought of this before I started recording..." - na that would take all the fun out of your videos!   ;-)

[thdwdr]

Lexan cover and some tri-colour leds illuminating the inside that change colour dependant on the voltage being output

[robertjung]

that board IS for 240V.. the capacitors are in series - as in many (all ?) ATX supplies.

[anachrocomputer]

When we go to the bunker (28:45), next to all those tins, over on the left-hand edge of the frame, is that an Apple Lisa sitting there? Fantastic passive thermal design in that machine for fan-free cooling!

[slaznum]

I'd be happy to buy from eBay and donate stuff like this because these are my favorite of all your videos (and mailbag of course). I like the discovery process and mystery solving I guess. Really great stuff thank you.

[pratherat]

Yeah, you're not going to close that back up permanently, but it might be convenient to add a series of jacks that connect to the important bits of the insides; those you might find yourself saying "I wonder what's going on inside there."

[nickkinnan]

I'd put a plexiglass sheet ("perspex" in UK/AU parlance?) on the top, just because I love seeing the internal workings of things.  It'd be no longer a "black magic box" but a "Wow, look at all the precision engineering that went into this! ... As I use it!" box.

[kevkabluebird]

Have the same exact unit but 220 V EU variant. The caps in the power supply are the same 200 WV.