911SC Clock Repair with annotated photos

[mhackney]

While I had my clock out to install the PCarMount I decided to fix the inoperative clock that has been bothering me for years!

This clock is from my 1983 911SC Cabriolet.

I've read all the posts here on clock problems - and there are many. It wasn't clear if the fix would address my issue so let me explicitly state my clock's symptoms first:

The Symptoms
The clock functioned - meaning that when driving, the hands moved and kept time if I reset the time. I verified that it was getting power with the car turned off, so it wasn't a power supply issue. Once I turned the car off, the clock would continue to run anywhere from 1 to several hours and then would stop until I next started up the car.

I decided to try the "capacitor fix" that others have described as there seemed to be some similarity of symptoms. The clock has a simple PCB with low part count. Really, the only component on it that could go south are the capacitors.

The Fix
The first step is removing the clock. The PCarMount came with a nice plastic tool for removing the instruments. It is now in my tool kit for future use! The clock simply prys out of its opening - it is held in place with a rubber gasket. Once you have the clock out, note the electric connector locations - there is a ground (brown) and power (black) wire. A photo is a good memory aid. Remove the connectors.

At your bench you can begin disassembly of the clock. Remove the rubber gasket. Removing the bezel to gain access to the internals is the most difficult/time consuming operation. I started with a small flat blade screw driver and slowly worked it under the bezel and advanced completely around. I did 2 passes of this to make sure the edge was lifted enough for the next step.

With the edge lifted using a screw driver, I used a pair of flat jawed pliers (smooth, no ridges) to flatten the edge. Again, working slowly and advancing completely around the bezel in 2 passes.

Carefully remove the bezel and place it and the glass on a clean surface. Try not to touch the inside of the glass or inside the clock dial.

The back case has 2 screws which must be removed. The blue arrows point to their locations. Next is a de-solder point, I used a small pointed soldering iron and some desolder wick.

Remove the clock internals. Here is the back of the clock PCB. There are 2 capacitors that must be replaced. It is important to keep the proper polarity. The (+) terminals are circled in red, the (-) in brown.

The culprit capacitors are the small gold "cans". Each has 2 solder joints that must be removed. I used desolder wick for these too.

The capacitors are standard 100µF electrolytic capacitors. I used 36V caps but anything in the range of 15 to 36V should be fine. Radio Shack carries these, I got mine from my local electronics store. Make sure to get the polarity right! The (+) and (-) terminals are clearly marked on them.

I don't have photos of the reassembly but it is basically the reversal of disassembly. Start by reinserting the clock into the case and attaching the two screws. Then desolder the connection on the back of the case. Slide the bezel and glass over the front of the clock. You must now bend the bezel flange back down over the case lip to secure it. I started with the small screw driver and simply went around the bezel and pushed it down. Once it was nearly in position, I used the flat nose pliers to press against it firmly to bend into place. Now re-install the rubber gasket, use a little liquid dish washing soap as lubricant.

TIP: if you scratch the side of the bezel, position the scratch at the 6 o'clock position on reassembly so you can't see it! You can also use a satin paint marker to cover any scratches.

Now is a good time to replace a burnt out bulb too. Re-install the clock by connecting the bulb and wires and sliding it into it's opening.

[86 911 Targa]

Originally Posted by mhackney

While I had my clock out to install the PCarMount I decided to fix the inoperative clock that has been bothering me for years!

This clock is from my 1983 911SC Cabriolet.

I've read all the posts here on clock problems - and there are many. It wasn't clear if the fix would address my issue so let me explicitly state my clock's symptoms first:

The Symptoms
The clock functioned - meaning that when driving, the hands moved and kept time if I reset the time. I verified that it was getting power with the car turned off, so it wasn't a power supply issue. Once I turned the car off, the clock would continue to run anywhere from 1 to several hours and then would stop until I next started up the car.

I decided to try the "capacitor fix" that others have described as there seemed to be some similarity of symptoms. The clock has a simple PCB with low part count. Really, the only component on it that could go south are the capacitors.

The Fix
The first step is removing the clock. The PCarMount came with a nice plastic tool for removing the instruments. It is now in my tool kit for future use! The clock simply prys out of its opening - it is held in place with a rubber gasket. Once you have the clock out, note the electric connector locations - there is a ground (brown) and power (black) wire. A photo is a good memory aid. Remove the connectors.

At your bench you can begin disassembly of the clock. Remove the rubber gasket. Removing the bezel to gain access to the internals is the most difficult/time consuming operation. I started with a small flat blade screw driver and slowly worked it under the bezel and advanced completely around. I did 2 passes of this to make sure the edge was lifted enough for the next step.

With the edge lifted using a screw driver, I used a pair of flat jawed pliers (smooth, no ridges) to flatten the edge. Again, working slowly and advancing completely around the bezel in 2 passes.

Carefully remove the bezel and place it and the glass on a clean surface. Try not to touch the inside of the glass or inside the clock dial.

The back case has 2 screws which must be removed. The blue arrows point to their locations. Next is a de-solder point, I used a small pointed soldering iron and some desolder wick.

Remove the clock internals. Here is the back of the clock PCB. There are 2 capacitors that must be replaced. It is important to keep the proper polarity. The (+) terminals are circled in red, the (-) in brown.

The culprit capacitors are the small gold "cans". Each has 2 solder joints that must be removed. I used desolder wick for these too.

The capacitors are standard 100µF electrolytic capacitors. I used 36V caps but anything in the range of 15 to 36V should be fine. Radio Shack carries these, I got mine from my local electronics store. Make sure to get the polarity right! The (+) and (-) terminals are clearly marked on them.

I don't have photos of the reassembly but it is basically the reversal of disassembly. Start by reinserting the clock into the case and attaching the two screws. Then desolder the connection on the back of the case. Slide the bezel and glass over the front of the clock. You must now bend the bezel flange back down over the case lip to secure it. I started with the small screw driver and simply went around the bezel and pushed it down. Once it was nearly in position, I used the flat nose pliers to press against it firmly to bend into place. Now re-install the rubber gasket, use a little liquid dish washing soap as lubricant.

TIP: if you scratch the side of the bezel, position the scratch at the 6 o'clock position on reassembly so you can't see it! You can also use a satin paint marker to cover any scratches.

Now is a good time to replace a burnt out bulb too. Re-install the clock by connecting the bulb and wires and sliding it into it's opening.

Great write-up!

Exactly what I did several years ago.

Gerry

[TheSt|G]

Did you oil it while you were in there? Apparently that's the other half of the issue.

[mhackney]

No. The internals of my clock were very clean and I didn't think oil was needed.

I should add that the clock has been running for a week now and has been spot on the time.

[Tom F2]

Thank you for taking the time to write this up, Mike!

[mhackney]

Sure thing Tom. I see you are located in Taxachussets too.

Also, you hit the magic 901 post!

[mhackney]

Just wanted to report that the clock repair is going strong. The clock was still dead on after sitting over the winter for a few months.

[RSBob]

Great post. Thanks

[dyount]

Just spent the evening following your post and wanted to say thanks for the clear step by step solution that I never knew would be an easy fix

[mhackney]

Thanks. Nothing like a functional clock!

[DRACO A5OG]

Outstanding!

[boyt911sc]

After reading this thread, I have a good reason now to open and dissect this ailing clock. Maybe I could revive it back to life. Thanks.

Tony

[SC911SC]

Thanks mhackney for the write up. I just did my '83 coupe per your instructions and the clock is running for the first time in several years! Total cost: $1.60 for two capacitors. I love small projects like this that can get done in a couple hours.

[mhackney]

Cool, another clock saved from the ravages of time!

[AHudson]

Fantastic write up. Thanks for that. My clock symptoms were identical: Drive car, set the time, it'd keep it fine, then after shut off it'd run an hour or so, and stop. My car stays parked pretty much of the time as a weekender.

Though my car battery was getting weaker, it'd always start the car. Then one day, it decided it wouldn't hold another charge. I snatched the battery and replaced. Lo and behold, my clock has not missed a minute's time since.

Can't figure how the clock would not run, but the car would start? Nor if this is just temporary and I need to do the above procedure.

Thanks again for the great write up.

[mhackney]

It's coming up on 3 years and my clock is dead on time.

[KM1966]

Bookmarking. Thank you for the info!

[Street_Lethal69]

Thanks for being so detailed!

[Jonny042]

My 87's clock has been set to 9:11 for years..... might be time to change that. Thanks for the how-to!

[rokemester]

Great write up! A gift that keeps giving with great description of how to remove glass bezel of all 911 instruments.