How to determine a Powersupply pinout

I would try to figure out that part of the circuit and determine the voltages from that. First, figure out the ground or common pins.

There's no standard pinout. These 5-pin DIN power connectors more often than not had +5V, +/-12V and GND, but no guarantees.

You could do a lot worse than starting with Mr. Simpson's advice. Just open the case and look on the circuit board itself, and poke around with an ohmmeter on the 20K range. Even if the power supply voltages aren't silkscreened onto the board, you can make some easy assumptions. For instance, if you see a 16-pin 74XX IC, you've got GND and one of the power supply voltages right there. The pinout of an op amp will probably tell you the analog V+ and V-. Be sure to trace back to the connector before plugging anything in -- there may be voltage regulators on board that are regulating the power supplies.

If you've got a little time and patience, you might want to use eBay to find prior sellers of this piece of equipment. They may have more information to help you, or even may have scanned a manual which may have the information there.

You also might want to try posting at sci.electronics.equipment.

Good luck Chris

I started to write a reply, and then realized complications that I didn't feel like spelling out at the time.

ONe thought that occurred to me is that the AC adaptor could be AC output. In which case, one is likely looking for a bridge rectifier connected to the connector.

In that case, there'd be no continuity between the connector and the supply voltages of the IC. Likewise if regulation was on the board, there's be no continuity between the connector and IC power pins, since the voltage would go through a regulator.

The board should reveal enough information (unless someone's potted it or rubbed off all the IC numbers). But of course, being able to read that information depends on who is doing it. What's obvious for someone who's been around electronics for decades is not so obvious for someone who may be looking for the first time.

Michael

Thank you, everyone. I am going to take my time on this one. I have waited a few years to get one of these.. They are really rare. I notice on ebay you can't really search that far back on completed auctions. Is there any way around this? I used to be able to go back a year or two and see what items sold for but now it only goes back about a month. Here is the link to the unit I just bought.

I have never seen a manual for it and few people own one. I appreciate the help.

Thanks Russ

Michael Black wrote:

Hi, Russ. Sorry for your troubles. Don't give up yet, though. As I said, you just might hit paydirt if you post your query over at sci.electronics.equipment. That would be my first choice -- it's free, and someone might be able to give you a hand.

I can't see actually using this piece of test equipment without the manuial (and software?). You also could make some inquiries from the eBay seller, and ask if he could get you in touch with the prior owner. With a little encouragement, the prior owner might be inclined to look around in the file cabinets for the manual.

Apart from that, there are a few vendors of old manuals. You'll have to pay for the privilege, but sometimes the additional cost is just part of the deal. I won't purchase any piece of used test equipment more complicated than a handheld DMM without having the manual, and I usually can get it from one of these sources if it doesn't come with the instrument:

(bottom half of the page)

I like Manuals Plus as a first try. I've also heard great things about Ed Matsuda, although I haven't bought from him myself.

Even if the vendors don't list the manual on their website, they may have it. You can notify them of your requirement, and they'll keep an eye out for you.

Good luck Chris

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