[cctalk] Re: Replacement tachometer sensor for DEC RA80/1/2 drives ...

I have three DEC RA8x drives that have failed (all of them fault with "spin error") because of bad photo-interrupter tachometer sensors. After talking to a few friends, it sounds like this is a pretty common fault. Photo sensors like this are fairly common, even today, but the specific parts DEC used are weird and unobtainable. I designed a little PC board that uses an ITR9606 photo interrupter, a 2N3904 and a resistor as a replacement. Works great - gives a beautiful 5V P-P clean waveform and with the PCB it's a mechanical drop in replacement. Just screws right onto the original mounting holes and plugs into the original connector. I put the PCB design up on OSH Park https://oshpark.com/shared_projects/z8DSkQsP If anybody needs one you're welcome to order some PCBs and build your own. The ITR9606 is as common as dirt, and you can buy bags of ten on Amazon for a few bucks. I've also put a few pictures on the Facebook DEC Computer Users group. I'd post the pictures here, but I don't think cctalk accepts attachments. It's not really worth making a web page for it. Bob