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-   -   Replacing burnt parts in tachometer (http://forums.pelicanparts.com/porsche-911-technical-forum/630609-replacing-burnt-parts-tachometer.html)

E Sully 09-21-2011 05:26 PM

When I changed out the odometer gear I photographed it last year.

village idiot 09-21-2011 07:50 PM

I saw Warren's thread while searching for answers, but it was a bit technical for me as they were discussing wave forms and other things that were way over my head.

porwolf, again, that was an excellent(educated obviously) guess.:D

Ed, thank again for the pic and info. Looks like I have a little electrical experiment to perform this weekend.

rick-l 09-21-2011 08:27 PM

Anyone read German?

the bigger pdf file

SAY115 datasheet and application note, data sheet, circuit, pdf, cross reference, pinout | Datasheet Archive

rick-l 09-21-2011 08:43 PM

That 47 uF 16 volt capacitor may be shorted out also.

rick-l 09-22-2011 11:42 AM

EDIT: Never mind..... Realizing it was a speedo and not a tachometer I can see the similarities to a UAF2115

ok what does endstufe mean? schalllung? stromquelle?

http://forums.pelicanparts.com/uploa...1316716878.jpg

porwolf 09-22-2011 12:31 PM

Here is a translation of rick-1's diagram. Also:

"Endstufe" = End Stage
"Schaltung" = Circuit Diagram
"Stromquelle" = Current Source

http://forums.pelicanparts.com/uploa...1316719770.jpg

porwolf 09-22-2011 12:37 PM

Hi "village idiot" (Obviously NOT!!!) thanks for the compliments. Keep enjoying the Aloha state like I did visiting wise for years:

porwolf 09-22-2011 01:17 PM

Forgot to include Hawaii picture. We all like pictures. Here it is: Maui 1995

http://forums.pelicanparts.com/uploa...1316722624.jpg

village idiot 09-23-2011 11:18 PM

Quote:

Originally Posted by porwolf (Post 6269255)
Forgot to include Hawaii picture. We all like pictures. Here it is: Maui 1995

http://forums.pelicanparts.com/uploa...1316722624.jpg

nice!!
I'm going to try fixing this thing tomorrow. Will post results(if positive :D)

village idiot 09-29-2011 11:09 PM

well, I did manage to replace the resistor as well as replacing the broken odo gear. Unfortunately, while reassembling the unit I managed to break the needle shaft........ oh well, at least the guys at parts heaven had one on hand for a c-note and it's on the way. Thanks again to all those who helped:D

village idiot 09-30-2011 08:35 PM

Got the new(used) speedo and installed it. No joy, still not working. double and triple checked the wiring. The only thing I seem to be missing is the white w/red striped wire, which, if I'm not mistaken is only used for cars with cruise control or o2 mileage counter which I do not have.

I used an oscilloscope to check the trans-mounted sensor and it is producing a square-wave signal that changes in relationship to wheel speed. I'm stumped....................

HALP!

porwolf 09-30-2011 10:50 PM

Hi Tom,

you are really lucky with those speedometers!!! Looking around Pelican threads I found this one:

http://forums.pelicanparts.com/porsche-911-technical-forum/632126-video-how-test-speedometer.html

Could you do that test in the video?

Wolfgang.

village idiot 09-30-2011 11:17 PM

Quote:

Originally Posted by porwolf (Post 6285205)
Hi Tom,

you are really lucky with those speedometers!!! Looking around Pelican threads I found this one:

http://forums.pelicanparts.com/porsche-911-technical-forum/632126-video-how-test-speedometer.html

Could you do that test in the video?

Wolfgang.

Wolfgang, I didn't need the test rig as I just swapped the speedo into my 88 Carrera and went for a drive. In that car it worked fine.

I am 95% sure I have the wiring correct so now I'm thinking the sender is at fault. I just can't bring myself to order a new one from our host for $150 on a hunch.

Tomorrow I'll pull the sender and check it out.

village idiot 10-01-2011 02:17 PM

HAHAHAHHAH!! took the sensor out and cleaned it as well as the "well" that it sits in. Also made sure the sensor was oriented in the well. Took it out for a spin, and to my surprise it worked!!
Not 100% perfect though, as it seems it reads a bit high. Oh well good enough to pass inspection.......Now on to the inop tach.................:D:D:D:D

Omegaman 05-19-2016 01:29 AM

Very useful info here, helped me fix my speedo. I had an open circuit 1n4148 diode and leaky 47uf 16v capacitor. Speedo swings full range at 12v 300HZ square wave.

Thanks!

oarable 05-19-2016 09:24 AM

Thanks for the pic E Sully. That is a great help! http://financeseeyou.com/red/images/7.gif
http://financeseeyou.com/red/images/8.gif http://financeseeyou.com/red/images/51.gif


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