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Old 09-09-2005, 07:50 PM
Angel Angel is offline
I miss my MBZ
Join Date: Feb 2003
Location: Cincinnati, OH
Posts: 562
Long walk through dense forest - anybody up for it ?

I too have a suspect tach amp - I've been trying to mount a tach in my 240D (more news later...)

I took it apart, and took a dremel wire brush to the silicone goop - there is a LOT of that stuff- but the wire wheel (stainless) seemed to whisk/melt it away without doing TOO much damage

I made a pencil drawing of the botton of the circuitboard, wire colors are mapped out, I could post this stuff up BUT:

1) I accidently wirewheeled off the markings on a big capacitor - no longer readable

2) There is a 14 pin DIP (microchip thingie) in the middle of the board - I dont think it had any markings on it when it was put on - I left the top untouched so I didnt remove any more markings - but I cant find any. Some of the pins are unused, but that doesnt make it any easier (unless we have some **serious** EE power on this board.

3) most of the rest of the components are simple resistors or diodes - It'd be tough to read the values on everything else but could **probably** be done = more than I cared to do last night.

I'm not sure how many 14 pin DIPs there were in 1970-something (when this was designed ?) but unless someone on the board thinks that they could piece together the DIP and the capacitor (or dremel apart thier own tach amp and hope it is marked better) I'm not inclined to continue my quest - any thoughts ?

(I may have big news for 240D owners that want a tach though- it looks like the pickup from a 300D should fit - I've yet to test - I'll put results in the 240D tachometer thread when I get them...)

Does anyone want to walk with me on this tach amp thing ? I dont have a digicam (seeing the size of things might help) but I can steal my brother's if I need to.

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