Tach not responding

[930 porsche]

Jim,

I am in Naples Florida. Yes I did stroke the grounded wire to the tach and nothing. Have you ever open any of those dashboard guages? Maybe there is a fuse inside. How do you open it? Is there a technique to do so?

[jimmcc]

Sorry. I was out yesterday.

Yes, I have opened a tach along with other Porsche gauges. I doubt you will find anything visibly burned but if 400+ volts went through it that could be a possibility.

I don't know if I know how to correctly open one. You might search on this site. All I know is how I was taught. The trick is to remove the bezel without damaging it. The pro shops replace the bezel and use a special crimping tool that correctly installs the bezel. You will never be able to duplicate that. However the rubber gaskets do a good job of covering any bends or scratches.

To open a gauge, lay the gauge face down on a towel to preven the bezel face from being scratched. Then, using a small jewelers screwdriver, force it under the bezel lip and slowly rotate the gauge or slide the screwdriverr and begin to open the lip. You do this in small stages to prevent damage and be careful as if the scredriver slips your holding hand becomes an available target. Then move up to larger screwdrivers and repeat until the bezel is free and rotates. I don't widen the gap until the bezel falls of as that leaves too much work to do reinstalling it but get it far enough that I can slip it off without bending it. The bezel is very flimsy so be careful after it is removed.

To reinstall, use a flat blade scredriver to re-crimp the bezel ring as you rotate the gauge. It's difficult to impossible to get it back smooth without any kinks. I haven't done enough of them to really say I'm good at it.

Your best bet might be looking in Pano or Excellence for the companies that repair guages and talk to them before proceeding on your own.

If anyone has a better technique, sound off. I'm open to learning.

Jim

[930 porsche]

Jimmcc,

Thank you for the explanation I will figure out how to close it without damaging the bezel.

[NathanUK]

Jim, glad I could help Shame I didn't have your knowledge though!

North Hollywood Speedo is a company that is highly recommended on these boards for instrumentation stuff. Maybe you should give them a call.

[930 porsche]

Nathan,

Here is the back picture of my speedo. If you can write the color of the wire on the picture I will sure appreciate it.

Thank you.

[sundevil64]

Originally Posted by NathanUK

Here's a shot of behind the tach.

Thanks for posting that pic. It fixed my problem. The PO had the wiring all jacked up. I thought I had a bad tach and boost gauge. Both work now. Pictures are worth a thousand words. I struggle with that elec schematic.