Speedometer PCB Repairable? 86.5
03-16-2018, 06:10 PM
#1
Rennlist Member
Thread Starter
Speedometer PCB Repairable? 86.5
I just pulled the speed o out of my '86.6 gold car I was using for DE's, I'm in the process of repairing the heater core and installing a new interior as the car has been rock solid.
After pulling out the speed o I now find the PCB at the back of it has a burnt resistor (note the speed o did not work).
Has anyone here repaired the PCB or should I just source a used Speed o?
Edit: just looking at 928 International's web site, they list a speed o for Auto and a diff part for 5 speed manual???
I get that the Tac is different due to the Auto has the Gear selector, but the speed o?
Thank you,
Dave K
After pulling out the speed o I now find the PCB at the back of it has a burnt resistor (note the speed o did not work).
Has anyone here repaired the PCB or should I just source a used Speed o?
Edit: just looking at 928 International's web site, they list a speed o for Auto and a diff part for 5 speed manual???
I get that the Tac is different due to the Auto has the Gear selector, but the speed o?
Thank you,
Dave K
Last edited by davek9; 03-16-2018 at 06:44 PM.
03-17-2018, 12:37 PM
#2
Rennlist Member
Thread Starter
Well Blake wrote this comment in the other thread:
"If it is just a resistor I would replace it. Using an entire new speedo is expensive and a resistor is like what, $1?
If it doesn't work, no harm no foul.
My odometer failing turned out to be the stepper motor failing and needing to be rebuilt (they are NLA).
I had it all done by North Hollywood Speedometer.
If it doesn't work, no harm no foul.
My odometer failing turned out to be the stepper motor failing and needing to be rebuilt (they are NLA).
I had it all done by North Hollywood Speedometer.
__________________
Blake G."
Thanks Blake!
I think I'll replace a few of the components, as something usually shorts out like a Capacitor, then the circuit draws too much current, smoking current limiting resistors, right?
I did search around and didn't find a PCB troubleshooting thread, if someone knows of one please point me in that direction,
Also still looking for whats is the difference between an Auto Speedo and a manual one?
Thanks,
Dave
Blake G."
Thanks Blake!
I think I'll replace a few of the components, as something usually shorts out like a Capacitor, then the circuit draws too much current, smoking current limiting resistors, right?
I did search around and didn't find a PCB troubleshooting thread, if someone knows of one please point me in that direction,
Also still looking for whats is the difference between an Auto Speedo and a manual one?
Thanks,
Dave
03-17-2018, 01:45 PM
#3
Thanks Blake!
I think I'll replace a few of the components, as something usually shorts out like a Capacitor, then the circuit draws too much current, smoking current limiting resistors, right?
I did search around and didn't find a PCB troubleshooting thread, if someone knows of one please point me in that direction,
Also still looking for whats is the difference between an Auto Speedo and a manual one?
Thanks,
Dave
I don’t see why and auto an manual speedo would be any different, butI don’t know that to be a fact. I have read a lot of swapping speedos and never heard of that issue coming up.
03-18-2018, 10:55 AM
#4
Rennlist Member
Dave - there is some info in this thread that might be helpful to you.https://rennlist.com/forums/928-foru...eter-gear.html
I used the vendor listed there - very inexpensive and speedo like new. That was for my 85. These are repairable for a lot less than a new speedometer.
I used the vendor listed there - very inexpensive and speedo like new. That was for my 85. These are repairable for a lot less than a new speedometer.
03-18-2018, 01:26 PM
#5
Rennlist Member
Thread Starter
Thanks guys, here's pic's of the burnt resistor, it really smoked
I may just shotgun it and replace some of the surrounding components, I miss our local radio shack
Dave
03-18-2018, 01:48 PM
#6
Rennlist Member
Hi Dave
Replacing the resistor will be easy enough, but there must have been a reason for it to self destruct like that. I agree that replacing other parts on that PCB would make sense.
Replacing the resistor will be easy enough, but there must have been a reason for it to self destruct like that. I agree that replacing other parts on that PCB would make sense.
03-19-2018, 10:23 AM
#7
Rennlist Member
Looking at the referenced threads here, it looks like this fried resistor is a common failure. In one photograph I can almost make out the color code, but a wire crosses right in front of it so I'm not sure that I've got it right. Does anyone know this resistor's value? And why it fails like this? Something for the maintenance info file.
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03-26-2018, 03:10 PM
#8
Rennlist Member
Thread Starter
I pulled another Speedo from a '86 manual cluster and for now just going to swap it to move this along as I think I have the spare heater core fixed and want to reassemble the dash this week.
It looks to be a 33 ohm 5% (orange, orange, black w/ gold.
I still need to figure and source the Cap's I think they are a 15 and a 100micro farad
03-28-2018, 09:00 PM
#9
You can call me Otis
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A link to my thread a couple years ago, MY '85.
https://rennlist.com/forums/928-foru...resist-er.html
https://rennlist.com/forums/928-foru...resist-er.html
04-02-2018, 06:45 AM
#10
Nordschleife Master
Useful thread, with resistor values, pics and links as well as discussion on the capacitors:
https://rennlist.com/forums/928-foru...r-failure.html
https://rennlist.com/forums/928-foru...r-failure.html