# an interesting little old board



## glondor (Jun 10, 2011)

Just thought I would share this picture of a little board I found. The interesting part is the glass components.


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## Militoy (Jun 10, 2011)

Boy that is quite an old PCB - those germanium diodes bring back a few memories! I can't see a number on them, but I'd almost bet they were 1N34A's.


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## glondor (Jun 11, 2011)

I will try to post a better pic Militoy. The little glass tubes have 2 gold "plugs" in each one. Which parts are the Diodes? the little round rainbow coloured ones?


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## Palladium (Jun 11, 2011)

glondor said:


> I will try to post a better pic Militoy. The little glass tubes have 2 gold "plugs" in each one. Which parts are the Diodes? the little round rainbow coloured ones?



The glass tubes are diodes. It also looks like the one by itself that is black with the silver strip on one end and the gold legs on it is a diode to. The strip is to indicate polarity or current direction flow. The rainbow ones are resistors and the color strip indicates resistance and tolerances.
http://www.web-tronics.com/1n34.html


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## Militoy (Jun 11, 2011)

Palladium nailed it - the photo is a little bit fuzzy so I can’t see any markings except for color codes – but the glass tubes with the red stripe on one end appear to be germanium diodes (the stripe is the cathode side). 3 sets of them look to be possibly connected in bridge rectifier configuration. The pancake-shaped ones with stripes are ceramic disc capacitors – 23 picofarads if I read the colors correctly as red-orange-black; The 2 large cylinders are paper capacitors if the coating on them is soft – but they could be power resistors if they have a ceramic coating; all the small cylinders with colored stripes are carbon resistors; the 2 silver cylinders and the black cylinder with a stripe are diodes (either silicon rectifiers or zener diodes). The markings on them should indicate exactly what they are, if you’re curious.


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## glondor (Jun 11, 2011)

Here are a couple of better pictures.


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## dtectr (Jun 11, 2011)

The variety of knowledge on this site never ceases to amaze me!

Would you guys say that it would be an engineering board, or test board, or whatever the correct terminology is? I have some of those (not that old & interesting! 8) ) in a batch of old components, & you can almost watch R&D's progression thru development.


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## Militoy (Jun 11, 2011)

Much better photos. The large devices are definitely rolled film or (more likely) paper capacitors – 0.1 microfarad at 400V. Surprisingly, the small, darker parts that appeared to be resistors in the blurry photos are actually more diodes. I can’t quite read the germanium diode part numbers – but that’s still what they look to be. The silver ITT parts appear to be 7.5V zener diodes. This board is a low power multi-output bias power supply of some kind – maybe with some DDL (diode-diode logic) signal steering thrown in. It looks to me like a regular, deliverable production PCB. The photo artwork for the traces was taped out by hand - but that would be typical for a board made before the mid-1980s.


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## glondor (Jun 11, 2011)

Written info on the board>>>> On the back Stamp GEPRUIT ESX-XE 68 There are 2 little dots above the letter U. Writing in solder,... Type d2-p2 Acid AK422339


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## Militoy (Jun 11, 2011)

glondor said:


> Written info on the board>>>> On the back Stamp GEPRUIT ESX-XE 68 There are 2 little dots above the letter U. Writing in solder,... Type d2-p2 Acid AK422339



I suspect the stamp on the back may read “GEPRÜFT” – which translates to “tested” in German.


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