VDO Clock Crystal Info?

[johncarlos2003]

hey thanks- i didn't know that- i guess it works perfectly! Thanks!

[Bill in OKC]

That is right - the chip is some kind of divide-by circuit and programmed by those traces that are drilled out - it counts the crystal oscillation and sends a pulse to the coil when a second has passed. I was getting just a very weak movement - not strong enough to pull the entire mechanism through a full step because the coil was minus the force of a few windings caused by burned/broken down insulation - the caps appears to allow the pulse through but no DC and also maybe to stabilize the power supply some. I read the white hand is maybe a trip timer?

[1982911SCTarga]

Bill, what do you think burned the windings on your coil? A serious over-voltage?

Brian

[Jascha]

After reading this thread I decided to try my hand and see what gives with my arrested VDO clock.

I checked the capacitor voltage as you guys noted and measured a charging voltage to ~ 12V with each tick. The resistance across the coil is 270 ohms (not isolated from loading circuit) but the clock is still not advancing. I upped the voltage to 14V and will see if that will add the needed force (the gears seem to move but obviously not the main minute drive)

Any suggestions (is the resistance indicative of coil winding problem ...?)

Jascha

[911FL]

I installed the two caps (thanks to Radio Shack) this evening and reassembled the whole affair - not quite believing it could be this easy - fixed alot of stuff in my life, but not car clocks. It's running great! One of the more satisfying projects yet.

Special thanks to Brian for the help and guidance in this repair. It worked perfectly and my clock is now more than just a fancy dash decoration. I will check it in the morning for accuracy and report back to the collective. Fantastic...

[1982911SCTarga]

That's great news, Don!

Isn't it cool to see that clock come back to life after a 20-year slumber? Not to mention that it makes the 911 dashboard more complete and purposeful.

I checked my clock this morning before leaving the house -- it's keeping great time. Too cool.

Jascha, are you saying you're clock is running when you test it? Sounds like you might have a problem in the geartrain if the motor is "ticking" and the hands aren't moving.

OK, two 911s leave New York for Los Angeles, one traveling at 140 mph and one at 125 mph. Before departure, both drivers synchronize their now fine-running VDO clocks on their dashboards. Which one's clock will be slower (very, very slightly) at the end of their respective trips?

Brian

[Bill in OKC]

My best guess is that the insulation broke down somewhere inside the turns and shorted causing a hot spot. It is a localised spot in the middle of the turns. If it was a serious overvoltage I would expect to see burned insulation everywhere.

[1982911SCTarga]

So that could be maybe a manufacturing flaw leading to failure of the coil?

[Bill in OKC]

Well I'm giving it the benefit of the doubt (I've only had this car 4 months) I'm guessing the insulation breaks down over time on some clocks, that is some really thin stuff. Probably normal wear and tear?

[1982911SCTarga]

Bill, I'm just hoping I don't have to go back in there (inside the clock) for awhile.

The coil on mine looked fine -- the windings were uniformly shiny -- so I didn't have any reason to suspect that component.

Brian

[911FL]

After twelve hours or so, the clock is spot on. The caps were the culprit and changing them out has brought this old clock back to life. I'm betting alot of the disfunctional quartz clocks out there have many of the simple to fix symptoms described in this thread, namely:

1) bad or leaking 100 uf caps available at Radio Shack for $1.29
2) bad gears (teeth missing or misalignment)
3) bad coil wires - replace the coil (or fix if possible)
4) blown resister (don't know the value but obtainable at RS as well

That's probably it, unless the actual circuit board gets burnt from current overload. As Brian said initially, this repair saves a bunch of money for other things, I'm thinking new front and rear shocks, bushings front and rear, and the list goes on and on and on.....

Oh yeah, did I mention how much I love this site?

[Bill in OKC]

You and me both brother! I will be checking the time regularly

[ducatist]

My car came from the PO with a dead clock (along with a list of other issues which I’ve now addressed), but I managed to get it working a couple of days ago. Unlike many on this thread, my clock suffered from multiple problems – some likely a function of age and others directly caused by the PO playing above his game. Once I’d determined that the gears were not jammed, I looked to the electrical system and found that the ground connection pin between the case and the circuit board had been poorly soldered and was no longer making contact with either the case or the circuit board. I soldered it back in place, but the clock still failed to function. Next, I checked the capacitors (one of which had been replaced by the PO). It seems the other one had failed and after I replaced it, the clock could be heard ticking when hooked to a 12V battery. I thought I’d solved the clock trouble until I reassembled the clock and tightened the two retaining screws on the back of the case. The clock stopped ticking every time I fully tightened the screws and would begin ticking again after I loosened them about half way. I assumed another component of the circuit board (positive polarity) was being pulled into contact with the case so I wrapped a piece of black electrical tape around the circumference of the clock works (taking care not to obstruct the movement). I then reassembled the clock and was rewarded for my efforts by a fully functioning and accurate dash clock.

So, if fixing one problem with your clock fails, don't give up…mine had three.

[JJ 911SC]

Originally Posted by 911FL

I installed the two caps (thanks to Radio Shack)...

... when 90% of the stuff at Radio Shack was electronic piece parts. Radio Shack basicaly kick start my 35 years of electronics job revenue after I got an "300 Electronic Projects Kit"; still got it somewhere in the Ratpack Cave

Similar to this but twice the physical size... How do they get my picture (me on the right, my brother "plane ears" is on the left) on the box???


:

Now it's about 1% if you find a Radio Shack??? Sadly, the name is gone in Canada

After the Lower 48s re-structuring, they now operate under the name; The Source

Now I have to go in the RatPack cave and find it... That will teach me from checking all the "New Post" My wife is going to kill me

[80-911SC]

JJ, I had that one and the following year got the 300 big kit they were a blast (circa 1980 +/-)

[JJ 911SC]

Originally Posted by 80-911SC

JJ, I had that one and the following year got the 300 big kit they were a blast (circa 1980 +/-)

That is probably the same one, it had a back panel. In the early 70, back them R.C. had a bunch a small books on just about everything; like Transistor, Power Amp and so on. I got (somewhere) about 50 of them.

In high schools I took a 2 years Electronic Program and all the instruments (Voltmeter, Oscilloscope, Power Supplies, etc...) came from Heathkit. The school order the stuff during the summer and we put them together in the first week of class.

Join the navy in 75, learn to speak English (kind of) and thanks to R.C. and the High schooll course, finish first in all the Military course even though I was the only French Canadian in the class

35 Years later bought my 1st Porsche. Working on my second one with the blessing of my boss

Salut

J.J.

P.S. I'll try to find the kit this week-end... Will get grief from the boss

[whiz05403]

Originally Posted by 1982911SCTarga

Just like the speedometer, you open up the clock by prying around the bezel that holds the glass on the front.

Once that is done, remove the two screws in the back of the clock housing. Then, you need to unsolder the negative (ground) connection from the back of the housing. Now you can slide all the clock components forward and out of the housing.

You should be able to check the gear train by carefully turning the motor and observing the gears moving and eventually the minute hand moving. If your gear train is OK, you've likely got something wrong in the clock's electronic circuit.

How do you "UNSOLDER"??

I have my clock in my hands, slowly prying the bezel, I have both screws removed, clock is sort of loose on the inside, I'm worried about the "soder" on the back casing.

Is it difficult to reassemble after all the prying?

Thanks

[whiz05403]

OK, now I have the Bezel off, the screws off but something (the solder?) is still holding the clock face and inards in the casing. Help!!

[whiz05403]

OK, so now I have the clock away from the case by unsoldering the back solder. I hooked it up to 12v and say faint movement of a little silver gear thingy in the clock. Looked more like a weak ossilation than turning, hard to tell. How do I replace the capacitors? Do I unsolder those as well?

Come on Pelicans, need some help here!!

[JJ 911SC]

Originally Posted by whiz05403

... How do I replace the capacitors? Do I unsolder those as well?

If they are soldered in, you will have to unsolder them.

If they are polarized, make a note of where the + side is.