EEVblog #649 - Power Designs 2005 PSU Teardown

[EEVblog]

What's inside a 1964 vintage Power Design 2005 Precision Power Supply?
Schematic: http://www.rako.com/Articles/assets_c/2011/05/Power_Designs_Model_2005_Schematic-thumb-512x331-53.gif

[robrenz]

Beauty    The main thread on these PD supplies is HERE.  That is an older version with the flat face meter. The later 2005A units have the edge style meter.

Please do a video with calibration, stability and ripple tests. Put that 34461A charting to work   IIRC you need to adjust zero pot at zero output first then calibrate at 20V output.

Now you need a HP6114A or HP6115A to take the old school up a notch

[BravoV]

Ok, its started, all cheap PDs and 611xA will be gone soon, hurry guys ! 

[gregallenwarner]

Very interesting, Dave! Even if you decide not to try and bring it back into spec, I'd still love to see the output of this thing on the scope, to see if it can still hold its own as far as ripple and stability go!

[Mandelbrot]

Awesome.   I just heard about these things last week from the thread on the forum, and now this video pops up! I would personally love to see a calibration video on this.

I'm also really glad I bought a TW5005W on ebay on Friday instead of waiting! No doubt the market for these will increase after your video.

[FrankBuss]

I think it is easy to bring it back into spec. Depending on the direction of R12, removing R79 should help, so that you can adjust it from 0 to 200 ohm instead 0 to 100 ohm. If it is the other direction, remove R79 and solder 100 ohm in series to R12 (but you should use one of those old carbon resistors ).

That's nice with these old devices. They will still work in 100 years, unlike modern microcontroller controlled devices, where the flash memory will be lost by then.

[warp_foo]

Nice video, Dave! Thanks.

Two things:

1. I already have a PD 2005, so I don't need to worry about the eBay 'eevblog' effect. 
2. Yes, a repair/cal video would be appreciated

m

[dentaku]

The way the front panel is designed makes it look like it's meant to be mounted in a rack.

[Mandelbrot]

The way the front panel is designed makes it look like it's meant to be mounted in a rack.

There was an adapter available for mounting these in a standard 19-inch rack. It is however designed for bench use. Two can be mounted side by side on one of these racks.

There is a manual for the model 2005 here: http://www.ko4bb.com/Manuals/09%29_Misc_Test_Equipment/Power_Designs/Power_Designs_2005_Power_Supply.pdf

[PedroDaGr8]

Ok, its started, all cheap PDs and 611xA will be gone soon, hurry guys ! 

Haha no joke. I just pray he doesn't do a 611x teardown. They are already so damn hard to find. If he was impressed with this design. Imagine him looking at the 611x.

[BravoV]

Haha no joke. I just pray he doesn't do a 611x teardown. They are already so damn hard to find. If he was impressed with this design. Imagine him looking at the 611x.

Actually its not the 611x tear down that I'm worrying about, it is the moment Dave decided to test and demonstrate in the video it's accuracy, stability and regulation under his scope view, and tortured with a "dynamic" load, not just static load.

If that really happened, then we will be in deep trouble finding it. 

[Rigby]

They're only hard to find if you have a budget.

I call my management out every time they say "there just aren't people available with those qualifications."  There are plenty folks with those qualifications, they just ask for wages that match their talents, and that removes them from consideration.

[Vgkid]

I don't think that I will be able to afford one now... I guess I will roll my own then.

[PedroDaGr8]

They're only hard to find if you have a budget.

I call my management out every time they say "there just aren't people available with those qualifications."  There are plenty folks with those qualifications, they just ask for wages that match their talents, and that removes them from consideration.

Of course, as hobbyists most of us have a limited budget. If budget was no option, we would be looking at the modern equivalents at 50x the price. So while you are correct, the budget in this case is implicit. A meter with these specs that fits within our budgets.

[calexanian]

That is a turret board. Very common up until the 70's in high stability or military equipment dating all the way back to the 30's. They are still used in fancy schmancy audio and guitar amplifier circuits because, well, it looks cool! Look closely at the way the wire is wrapped around lugs and notice the sparing use of solder. This is straight out of the military servicing manual. They would even specify the angles of the bends of the wire. Very cool stuff. One day I will post scans of one of those manuals regarding wire wrapped solder lugs, those nifty split turrets, and the eyelet turrets. You can get your bottom dollar those joints are good.

As for the unit being out of spec, are you still as "In Spec" as you were at 18? Most likely not. Couple things come to mind. The electrolytic caps are due for a change, and those carbon resistors are going to drift. You could do the lazy mans job (And in this case its the way I would probably go) and bodge in a resistor to bring the divider string into cal, replace the filter capacitors, and call it a day. I have an E/M scientific supply from about the same time. Not as well made, but it can supply up to 110 VDC at up to 1.2 amps regulated. It has 2 puck style germanium pass transistors on it and groans when you swing the voltage around! Just for kicks I light my office lab with a hundred watt bulb with regulated DC. Its like thousand dollar champagne. Is in no measurable way better, but wasteful and unnecessary, not to mention fun!

[coppice]

Schematics with negative at the top and positive at the bottom were very normal in the 60s. Most designs were very PNP transistor centric in those days, and a PNP oriented schematic looks more like a valve/tube schematic when you put the negative at the top.

It looks like everything in that PSU is silicon. Most designs in 1964 were full of germanium transistors. Many PSUs even had copper oxide rectifiers at that time.

[coppice]

That is a turret board. Very common up until the 70's in high stability or military equipment dating all the way back to the 30's.

I think 1964 was before the introduction of plated through boards. They were certainly not in widespread use then. Turret tag boards are more reliable than a single sided PCB, so it was the most appropriate choice for a product like this supply.

[Dave Turner]

That reminds me of a lot of kit that I picked up at the Army & Navy stores in the 60's when my soldering iron was a lump of copper on a stick heated on the gas stove.

Oh - you wanted a greybeard - it took some time to get the tongue at the right angle!

[EEVblog]

Oh - you wanted a greybeard - it took some time to get the tongue at the right angle!

There's a tongue in there?   

[EEVblog]

As for the unit being out of spec, are you still as "In Spec" as you were at 18? Most likely not. Couple things come to mind. The electrolytic caps are due for a change, and those carbon resistors are going to drift. You could do the lazy mans job (And in this case its the way I would probably go) and bodge in a resistor to bring the divider string into cal, replace the filter capacitors, and call it a day.

Yes, will probably do at least that. But would be nice to hunt down the drifting culprit.

[G7PSK]

I would clean that big wire wound trim pot before doing anything else, the wire and the wipers in them develop a patina over the years and cause the resistance between the wire and wiper to rise.  I have taken them apart in the past and rubbed the wire face with very fine wet and dry along with the wiper.

[SpiderElectronics]

Love it. Nice piece of gear that.
I remember back in 1985 at University learning Electronic Engineering I had to do a section on loom wiring and lacing up just like that power supply. Fantastic, IWOOT!

[Kjelt]

I love those old school wirelooms cablestitching.
I once learnt it 20 years ago from a friend but due to lack of exercise forgot all about it in time.
They are much better then those nowadays plastick tiewraps that stick out and are always in the way.
Found this document online how Nasa does it, time to learn to stitch my knots all over again 

[robrenz]

Since these supplies have very low ripple. It would be interesting to see it measured with a DSA, SA, scope, rms AC meter and see how the measurements correlate between instruments.

[dr.diesel]

That old beauty absolutely deserves a proper referb and cal.  Another vote for making it so,