Quartz clock running backwards in 73’ 911

[rching]

Sounds silly but I had my quartz vdo Porsche clock repaired. When I got it back, it ran backwards. Really! I sent it back in and when I got it back the second time, it was running great. It’s been a while since I drove the car. I have a trickle charger on the battery and when I got in today, it fired right up. I looked at the clock and it’s running backwards again. Disconnected the battery and then reconnected but it’s still going backwards! I’m wondering if anyone else has had this problem and a solution before I contact the host again? How can a clock do that??
TIA. Rching@usc.edu (I check that more than on pelican mail)

[porschedude996]

Better unplug it when you get to ‘73. It will revert to raw material.

Just kidding, That is very weird, send it back.

[snbush67]

[porschedude996]

You might try sending to someone else. A frequent PP forum member by the name of John Bell (JBell) does a splendid job. He went through all of my instruments and also built a Air/Fuel Ratio Gauge for me.

[EC900]

Who fixed it and was it running in reverse before? Did they just clean or did they replace anything?

Beyond cleaning connections and inspect wires for breaks or pinching, more repeated disconnect/connects to try and get movement to react, there’s not much else to DYI about the issue. No point in trying to fix something the repair service was supposed to do unless they can direct you otherwise.

Curiously it’s a ‘73 quartz movement…right (?) is the back of the case date marked w/ ink stamped or was face replaced for modern look. Also, are you hearing a steady seconds ticking? In a quiet garage, I can hear my VDO quartz movement operating steady with the seconds ticking. I don’t know what a VDO mechanical clock sounds like if there’s a difference.

BTW is clock running backwards only when the car is on and running, and when it was shut off, did it keep correct time? Heck, it may seem to be going in reverse but it’s really stopping altogether at certain points along the revolution.
FWIW I use a battery tender for storage too, my quartz VDO has a tendency to run few mins slow over a couple weeks or months, why I don’t know but driving for hours and the time is correct. Doesn’t seem when car is off the clock wants to keep up. It’s not a precision timepiece but quartz is quite reliable so a twist or two to set correctly isn’t a bother.

I would suspect bad connection ground or power, so clean up the connections there including the fuse terminals which i think is on the instrument light circuit too. Aside from something electronically internal affecting the reversal of the movement. You have your 12.9-13v at the battery with or w/o a battery tender but what power is reaching the clock. Doesn’t seem this would cause a sudden or intermittent reversal of the clock but intricacies of the movement could be affected by road bumps and electrical surges while on a tender.

Another Example….we all have a quartz wall clocks that have a sweep second hand. Ever notice that when the battery is weak, kind of twitches and stops? That weak 1.5v would cause the quartz movement to slow to the impulses and not have enough energy to get the movement going forward past the 6-7 o’clock number. It’s sort of like struggling to go uphill only to fall back a step or two. Going downhill, then by gravity moving has no problem. This would be obvious if VDO had a sweep second hand.
If the VDO is of some unique design that has no mechanical feature (a cog) to prevent reversing the movement (its a circuit I think) whereas a mechanical clock does have this, something that I’d ask the repair service. But they would have pointed that out if it were a mechanical movement vs quartz.

Did you try to repeatedly connect/disconnect several times or hook up on a bench and add 12v power? Still this is something that should have been done at the repair outfit.
Just could be a bad quartz movement, board solder cracks and capacitor issue which seems to be the case in many of these VDO clock issues.

Anyway, maybe in the meantime if you want… check if the minute hand is moving slower in reverse than if it were forward - say the 6 o’clock position vs 12 o’clock position (upper vs lower hour mark). Same would apply if it’s currently moving correctly. You can set the minute hands at 7 or 5 and see how it reacts. Never turn the hands counterclockwise, old gears too fragile and never a good idea for daylight savings time adjustments.
Also check and see if the time is of any accuracy going backwards or forwards, for a period of an hour or two and ever longer. Maybe set up a time-lapse feature on a camera phone with a tripod for a few noted hours.

Bottom line; You can go through all this on your time and effort and still not get anywhere aside from making sure wiring is ok. Quartz is suppose to be reliable but it is microelectronics after all.

This might help explain something to the repair service to reevaluate what they’ve done besides a typical standard R&R.