Where can I get an old board re-built?

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nuckythompson

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Nova Scotia
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Hi there, anyone know where I can get an old board like the attached built? No longer made by OEM, hoping they can at least send me a schematic and I could have it rebuilt... thanks!

Old board.JPG
 
230208-0837 EST

nuckythompson:

The semiconductors and electrolytic capacitors are the most likely to have failed.

Are there any parts of the board's conductors damaged? May point to a failed component.

Find an electronics repair facility in your area.

The board looks in relatively good condition, but may be dirty in certain areas. However, that reflection may be just normal for the way it was lighted.

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Is there evidence that the board itself (very likely made of epoxy-fiberglass like FR-4) or its circuit traces are damaged? If not, perhaps one or more failed components could be identified and replaced. It appears to be maybe a 1970s or 1980s vintage design based on what look like TO-8 hermetic packages for the 4 semiconductors on the upper right. The upper two are likely to be OP-amps or comparators, with signal levels adjusted by the two single-turn potentiometers, and the two blue multi-turn POTs perhaps adjusting an offset or threshold.The semiconductors labeled Q1 and Q2 are likely to be transistors if they have three leads.

The two electrolytic capacitors on the lower right are the most likely components to have failed given the age of the board. The semiconductors would be most vulnerable to any overvoltages / surges. Of course, a visible inspection should be done to identify any apparent physical damage on the components. At least continuity tests could be done on the transformers. Since there appear to be two identical signal channels on the board, resistance measurements across corresponding points on the two circuits could be made (including across individual components) to see whether any significant differences can be found. Such differences could help narrow down where a failed component might be.

Can you tell us what the basic function of the board is, or what type of equipment that it's in? What kind of symptoms did the board failure present?

I see that gar has just posted similar comments,
 
The four diodes (perhaps Zeners?) on the lower left should be checked, since they appear to be at the inputs or outputs of the board. And so they might be more exposed to external surges. There are also other relatively small diodes on the board that could be checked.
 
I’ve had good luck taking old boards to Galco for service and providing them with a machine wiring diagram. And a functional description of how it is supposed to work.
 
Whatever it is, everything appears to come in pairs. Maybe a redundant power supply, or maybe a full wave power supply?

All the components are probably labeled, and they are probably all standard components.

It looks like it would be possible to just replace every single component, as a last resort if nothing else.
 
A wild guess is that it's a demodulator for processing the two quadrature AC outputs of a "resolver" that's used to sense the angular position of a shaft. The two transformers on the board would step down these two AC signals which could be over 100 volts down to lower levels that the electronics can easily handle. The two demodulated signal outputs would represent the sine and cosine of the angular position. The two 1-turn POTs would be adjusted to get equal gains on the in-phase and quadrature channels, and the blue multi-turn POTs would be used to eliminate any DC offsets that might be present.

https://www.digikey.at/en/articles/...angular-position-and-velocity-with-a-resolver
 
synchro said:
A wild guess is that it's a demodulator for processing the two quadrature AC outputs of a "resolver" that's used to sense the angular position of a shaft. The two transformers on the board would step down these two AC signals which could be over 100 volts down to lower levels that the electronics can easily handle. The two demodulated signal outputs would represent the sine and cosine of the angular position. The two 1-turn POTs would be adjusted to get equal gains on the in-phase and quadrature channels, and the blue multi-turn POTs would be used to eliminate any DC offsets that might be present.
Click to expand...
That's exactly what I was about to say. :sneaky:
 
Should not be too hard.
Check to make sure those solid state parts are still available.
Test the transformers.
Test the pots.
Replace all the caps.
See if it works.
Replace the solid state parts if not.
 
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