radio shack MD-981 diode replacement help


SeaGtGruff

I meant to play that note!
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Wow! I had no idea that Radio Shack ever made musical keyboards! I see some MD-981s for sale on eBay (if those listings are still current), in case your friend needs to buy another one for spare parts. It looks like Radio Shack even made at least one 76-key model. :)

I'll keep looking on the web to see if anyone's posted a service manual for it.
 
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happyrat1

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Those look like they may be Zener Diodes.

I'd suggest removing a good one and testing it to see if it is in fact a zener and what voltage rating it is before sourcing a replacement.

Even so, it would be worthwhile testing to see if it's a germanium or a silicon diode as well even if it's not a zener.

If you can find a schematic or a parts list then your problem would be solved.

Gary ;)
 
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Those look like they may be Zener Diodes.

I'd suggest removing a good one and testing it to see if it is in fact a zener and what voltage rating it is before sourcing a replacement.

Even so, it would be worthwhile testing to see if it's a germanium or a silicon diode as well even if it's not a zener.

If you can find a schematic or a parts list then your problem would be solved.

Gary ;)
I looked everywhere for a service manual. I can only find a user manual unfortunately.
 

happyrat1

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Then your buddy better bone up on test techniques and learn how to identify and source the part by electrical characteristics.

It really is a pretty ancient and cheezy board to begin with. May not be worth the effort.

Gary ;)
 
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tjw

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I'm willing to help in the identification process if your friend wants. But @happyrat1 has it right, it's probably not worth the investment, unless he/she has access to few pieces of electronic test equipment.
 

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