911 clock

rwarner007 · 02-26-2011, 07:15 AM

I'm having problems with my 1984 911 clock. It is a VDO quartz. The thing runs sometimes, and then doesn't.

I took it out of the car, hooked it to a regulated supply, and it ran perfectly for days on end.

When I plugged it back in, the clock started right up and ran on my commute to work. Getting back in the car, I noticed the clock had stopped about 30 minutes after I had killed the engine.

I can't figure any rhyme or reason to this, but it seems to be a wiring issue.

First things first: several people have been behind the dash of this car. A black wire and a brown wire are plugged into the clock. Is this correct? If it is, then it's time to run new wires.

Thanks.

rwarner007 · 02-26-2011, 07:21 AM

If it is wired correctly, is it possible something is loose within the clock? Should I take it apart and look for loose solder connections?

cdrik915 · cdrik915's Garage

Hi mate ,

On my own , just an electronic component that is dead inside the clock.

rwarner007 · 02-26-2011, 07:48 AM

I noticed the clock has a couple of capacitors. Could this be a symptom of a bad one? It looks like a fairly simple fix if so.

ossiblue · 02-26-2011, 08:26 AM

I agree that it's probably something internal to the clock but you should check out the wiring first as it's the easiest to check. The clock on my 73 does the same thing--keeps perfect time for days on end then, suddenly, I'll find it's lost an hour or so though it's still running. Haven't cared enough to dig into the internals yet.

tomphot · 02-26-2011, 09:04 AM

Same problem here - it seems that if I'm driving the car every day for a week, it keeps perfect time. As soon as I let it sit for a couple days, it looses a couple hours.

James Brown · James Brown's Garage

Check the voltage at the clock lead after you shut down the engine, should be above 12 volts.

rwarner007 · 02-26-2011, 09:54 AM

Clock lead voltage checks out ok. Now I need to figure out how to take the cover off the clock.

porschenut · 10:09 AM

If it runs perfectly outside of the car, then I don't follow the logic that there can be anything wrong inside the clock. It has to be the car's wiring, loose connection, fuse connection, or something like that.

Next time you drive to work, leave the clock out of the dash so you have access to the wires. Check for voltage when you leave, and then when you arrive. After a while, go back to the car and check the voltage again before turning the key on. If the voltage disappears at some point, you know it's not the clock itself.

DRACO A5OG · DRACO A5OG's Garage

it is held on by screws and a solder point, take care to re-solder properly when re-assmebling.

Try re-freshing the connectors by squeezing them so the will be tight, cleaning them will not hurt either

rwarner007 · 02-26-2011, 11:50 AM

This is the thing about diagnostic testing: at times, it is just try-this-then-that. I got the clock apart (pics to follow). The step motor wasn't working. Replaced the two caps, a really easy task. Now the step motor works, but the gear train seems to be really finicky. If not just right, the hands do not move! This may have been the REAL PROBLEM all along. The clock ran just fine in my house. A few potholes later, no. I'll keep pecking away at it.

porschenut · 02-26-2011, 12:36 PM

Hmmm. Sounds like it runs well when not subjected to vibration, and you found the culprit inside the clock after all.

rwarner007 · 02-26-2011, 01:42 PM

Success! My son and I made some macro pics of the innards of this clock and discovered a couple of things that have to be just right for it to work. I'll give it a couple of days to be sure we have a fix, and then try to post some pictures.

DRACO A5OG · DRACO A5OG's Garage

Cool, looking forward to it, I have an extra clock that needs fixen.