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HomeTech Articles > VDO Clock Repair

Pelican Guest Technical Article:

VDO Clock Repair


[Click on Photo] Foreward by Wayne:

     Demick Boyden has written us a fine article on how to repair your VDO clock.  The mechanisms from the various Porsche cars are very similar.  Although Demick speaks specifically of the 914, the VDO clocks that are used within the other Porsche models all share a similar mechanism, and the similar repair problems.  This article details the problems with the internal electrical solder connections that often fail.  There are a few other problems with the clocks that cannot be repared without special parts, such as new pendulum springs.  For clocks that need this additional repair, please contact Pelican Parts.


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Figure 1:
Two Different Clock Mechanisms
VDO Clock Repair

     There are two types of clocks styles available in the 914 that I am aware of. Both look identical from the front, but are easily differentiated from the rear and have very different mechanisms inside. Both are shown in Figure 1. In the spirit of VW, I will refer to the clock on the left as Type I and the clock on the right as Type II. To the best of my knowledge, the Type I clock is the earlier model, and the Type II clock replaced it in 1973.

     Comparing the two clocks, I like Type I much better. It is much easier to open up and you will have a much greater chance of successfully making repairs. Also, Type I has a way to externally adjust the speed at which the clock runs so you can dial it in to be quite accurate. Type II has a different clock mechanism which presumably eliminates the need for adjustment (since there is no external adjustment, although I believe there is an internal adjustment), but I have never had experience with an operating Type II clock so I cannot verify its accuracy.

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Figure 2:
Standard 3 Gauge Set on the 914

Type I

     The Type I clock has an easily removable rear cover. Three small nuts are all it takes to remove the rear cover (you may need to break the small plastic that goes around these nuts if the clock has never been opened up before). Inside you will find a series of gears and a coil and a couple of springs (Figure 2). There is a steel disk about " in diameter near the rear end of the clock which has an electrical contact mounted under it. When this electrical contact is closed, current is sent to the coil which spins the steel disk around about turn. This is how the clock is wound. The disk is spring loaded and will slowly over the course of about 3-4 minutes return to its original position - operating the clock as it goes around. When the contacts close again, the process starts all over again. For this reason, this clock only uses power for a fraction of a second every 3-4 minutes. You can turn the disk manually and see how this all works. The rest of clock works like a regular clock with all of the gears, etc.

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Figure 3:
Standard 3 Gauge Set on the 914
     This clock has a built-in fuse, which is what is normally the cause of this clock not working. Right next to the coil is a set of metal tabs which should be soldered together (Figure 3). If your clock is not working, chances are that these two tabs are no longer soldered. The process to repair it is simple: resolder the connection. To do this correctly, you need to use a low temperature solder (specification is solder with a fusing point of 120C or 248F). Where to find this? I don’t really know. I had some low temperature solder laying around which came in strips and was designed to be wrapped around a wire and then melted with a match. It never worked good like that, but it worked fine in this application (minus the match). I don’t know what the actual fusing point of this solder was though. Using regular solder is an option that will work fine, but someday your clock will really get fried because this fuse didn’t melt like it was supposed to and you will not be able to repair it. The choice is up to you. Also, when you solder the two tabs together, be sure that the top tab is pulled down (so it is spring loaded) to meet the other tab and then soldered. Don’t try to bridge the large gap because this spring loading is what helps to separate the tabs when the fuse melts. Note: The solder job shown is Figure 3 is NOT done correctly for exactly this reason (big blob of solder bridging the gap)

     Well, that’s about it! Put the rear cover back on and plug it in. Adjustment of the clock speed is made by the small slotted screw which protrudes through the rear cover. Counter-clockwise goes faster. Best that I can tell, each 1/8 of a turn affects the clock by about 5 minutes per day.

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Figure 4:
Standard 3 Gauge Set on the 914

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Figure 5:
Standard 3 Gauge Set on the 914

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Figure 6:
Standard 3 Gauge Set on the 914

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Figure 7:
Standard 3 Gauge Set on the 914


Type II

     Getting inside the Type II clock is a bit more difficult. Just like most all of the other 914 instrumentation, it involves using a sharp object (small screwdriver, chisel, etc) and carefully prying around the outside of the outer face ring. This part is a real pain. You will have to pry the formed flange up for at least of the way around the clock, and then remove the clock ring and glass from the rest of the canister. Now it is time to remove the guts of the clock from the canister: remove the 3 screws from the rear surface of the clock and unsolder the ground connection (Figure 4). The guts of the clock should now slide out (Figure 5).

     Once open, you will notice that the inside looks quite different from the Type I clock. This clock is run by an electric motor rather than a spring loaded disk wound by a coil. The most common failure with this type of clock is a damaged gear. In my case, it was a gear whose support shaft had broken. In order to fix this shaft, I wanted to separate the PCB portion of the clock from the gear portion (shown separated in Figure 6). This is possible to do given the following: Remove the obvious screw which holds the PCB on, and unsolder the two posts which are arrowed in Figure 7. These two posts are how the electrical connection is made to the electric motor. If you do not unsolder these posts, the PCB is still very easy to remove, but your clock will never work again. The posts will come out with the PCB, but the very fine wires which go into the motor will break and there is no way to re-connect them (I know, I’ve tried - that’s why the motor in Figure 7 is partially cut open). With the PCB removed, you can get access to do the gear repair. In my clock, I did the gear repair very carefully with epoxy, and then found out on re-assembly about the broken wires - but I am confident that the repairs would have worked had I not broken the wires.

     Re-assembly is just the reverse of this process. Test the clock before putting it completely back together (that face ring is really a pain - you don’t want to do it twice). Also, note in Figure 6 that there is an adjustment pot mounted to the PCB. I believe that this pot is the clock speed adjustment and it is not accessible except by clock dis-assembly.

     That’s about all of the tips that I have, so good luck in your 914 clock repairs! There are not all that many 914 clocks that still work. Maybe with this information, there will soon be a few more....

Comments and Suggestions:
Tracy Comments: I purchased my 83 911 SC twenty years ago. The clock gave up the ghost about five years ago. On examining the clock, it does not appear to be a type 1 or 2. The face of the clock says VDO Quartz Zeit. Was the original type 2 replaced with a quartz clock? Where can I buy a replacement quartz or can it be repaired?
November 1, 2014
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
 
Mike Comments: Any suggestions on a type 1 clock that only has about 40 seconds of run time before the contact closes. Keeps good time but how do I make it swing out further. I have cleaned and oiled it.
May 13, 2014
  Followup from the Pelican Staff: Nothing other than replacing it comes to mind. - Nick at Pelican Parts  
raykutner Comments: does anyone have details of how to take out the clock on 1983 944 I am baffled at this point
also have trouble with hood cable, it got bound up on front headlight and had to remove from latch and when redid wire thru latch, and now cable won't move latch at all
April 6, 2014
  Followup from the Pelican Staff: I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
Neilnaz Comments: I used this guide to fix my Type I clock from my 71T. Sure enough I found the fused link had gone. I cleaned the mechanism, lubricated the mechanism, soldered the link and connected it up to 12v. The clock immediately clunked and started to tick!!

I set the time and watched and listened. The clock remained ticking away and kept time. Over the next 20hrs it had lost 5 minutes. I decided to adjust the time 1/8 turn anticlockwise as advised and am awaiting the result. I will re-adjust until the clock keeps reasonably accurate time and re-install it in a few days time.

Great article and I am chuffed that my clock is ticking...

Neil
January 28, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Roger 911 Comments: The VDO clock in my '72 911 quit working over 10 years ago. I never bothered to fix it until a few weeks ago. I took it out, took off the back cover, and noticed a big piece of lint in the gears. After I removed this, it started ticking. I used a can of compressed air to clean out the rest of the mechanism and I re-installed it into the car. So far, so good. Hey, its pretty exiting anytime I can fix something on the Porsche for 0 cost!
December 29, 2013
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Deano K. Comments: Our 1973 Volvo 1800ES has a type 1 VDO clock in it which works fine, being that it's in a Volvo - ha! My question is has anyone found a brighter light bulb/LED to fit these clocks? The original is mighty dim. If asked and answered, my apologies, as I missed it.
December 16, 2013
  Followup from the Pelican Staff: I don't know of any. But our parts specialists probably do. GIve them a call at 1-888-280-7799. - Nick at Pelican Parts  
Jake Comments: Hope this helps someone, I found the sample schematic on the datasheet for the IC used in the clock in my 1986 911 matches the exact components in my clock. I found it in an ITT IC guide from 1977 pdf.

My clock 'tries' to run when power is applied, so it looks like it may just need cleaning / lubrication. What's everyone using?
December 7, 2013
  Followup from the Pelican Staff: Thanks for the input on this one. - Nick at Pelican Parts  
spiderscott Comments: Does anyone know how to get the hour and minute arms orange coloured ones off of a type 1 clock ?
July 3, 2013
  Followup from the Pelican Staff: I am not 100% sure on this one. I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
PPCCivilian Comments: the caps in my 75 914 type 2 are 47uf 16 v 2 and one of the caps was bad Positive lead was bad at cap
June 5, 2013
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
 
Bob Comments: I am attempting to repair a VDO clock out of a 64 220 Mercedes. I cannot get the movement out of the housing. The photo shows I have removed the bezel and exposed the dial and hands from the front. I removed the two dial screws but it can't come out through the front because the hands will not come off. I even bent the little metal disc with a watchmakers hand removal tool but it will not come off. The movement will not come out the back because the rectangular dial is too big to go through the round hole in the back. Does anyone have any ideas what to do next? Thanks for your help.
February 28, 2013
  Followup from the Pelican Staff: I can't offer too much advice. i wonder if you removed the silver retainer would the hands slide off. Then you would need a new part if it is damaged. - Nick at Pelican Parts  
rcdom Comments: Hi I have a type 1 where I had to remove the back plate with the connectors to replace the fuse with a copper wire to the coil and got it to work.Great.Does anyone know how much tension to put on the small arm that drags on the brass wheel?
January 27, 2013
  Followup from the Pelican Staff: I do not. I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
Volvo_1800 Comments: I have the Type 1 VDO Kienzle clock that I let sit in my unused car for a few years. As the battery drained down, it lost the power to open the contacts. The low-temp solder fuse melted as designed, but not enough to completely open the circuit. You can see this in the attached photo. Also, you can see that the electro-magnet coil overheated from the closed circuit, and the insulation melted, allowing a short circuit on the coil. So I need to remove and replace this wire with new electro-magnet coil wire. Does anyone know the gauge of this wire, and the number of revolutions?
October 21, 2012
  Followup from the Pelican Staff: I am not 100% sure on the specifics.

I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
Jack Comments: I have a 1969 Porsche 912 and the clock is running slow, about one hour every 12 hours. I have read all the comments and are confused whether the clock can be removed from the front. Comments?
October 21, 2012
  Followup from the Pelican Staff: I apologize, I mistook your comment as a 914. The clock has to be removed from inside the truck or through a speaker grill. See this discussion. http://forums.pelicanparts.com/porsche-912-technical-forum/663400-how-remove-clock.html - Nick at Pelican Parts  
Don Comments: I have a slow clock on a '67 912 that I was to fix. To remove it you have to go in from the trunk. However, the wiper motor is in the way. Is this easy to remove? Thanks, Don
May 31, 2012
  Followup from the Pelican Staff: If you unbolt the motor, you should be able to swing it to the side enough to gain access. - Nick at Pelican Parts  
airbil Comments: As stated; general failure is the two capacitors. $1.79 at radio shack # 272-1028.
Gently pry clock for 911 dash with cloth cover flat screwdriver.
Even more gently, bezel must be pryed back from housing. Start with small screw driver and progress to larger one.
Remove the screws on back of housing. De-solder the ground and the clock mechanism will come out.
HAVE a good soldering iron and good soldersilver.
Pay attention to the + and - orientaion on the PCB board and new capacitors. Only negative - is marked on each if I recall.
Also inspect the gears all the traces on the PCB. Small wires can be soldered to from point to point to reconnect broken traces.
Take your time. Remember; brown wire is ground, black is power.
The clock may last forever now.
Tick, tock on !.. MacDuff.
April 10, 2012
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Arnold Comments: How is clock removed from center console to repair or replace?
March 15, 2012
  Followup from the Pelican Staff: On what model? on a 914, remove the plastic trim panel that houses the clock. Then remove the clock from the panel. - Nick at Pelican Parts  
Don T Comments: On the VDO clock Type II, what is the number for the replacement bulb?

Also, is there an LED that can be used in place of the bulb, if so what is the number? Thanks...Don T
December 31, 2011
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
nigel Comments: Do you have a 1986 Porsche 944 digital clock replacement or repair option.Still working but heat has upset display and maybe requiring a new bulb as well.
December 4, 2011
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
mickyt Comments: Do you know where i can get a replacement glass ?
October 16, 2011
  Followup from the Pelican Staff: You didn't mention what vehicle you own.

Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
MarcW108 Comments: Just an update on my previous post. After making many tiny adjustments to my Type I clock, it is now running acceptably accurate. The clock is loosing about 1 minute every 2 weeks!
April 28, 2011
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Donald T Comments: I just changed the clock on my '68 912. The original clock is similar, but not identical, to the type 1 clock. It was a bit more difficult to remove as it was held into place by a couple of knurled brackets that must be unscrewed from the trunk. I replaced the clock with a later model but very similar quartz VDO clock. Keeps perfect time! Comment: after soldering the burnt fuse it might be wise to put an inline fuse to the power line. Much easier to replace and it should prevent a burned out clock.
April 5, 2011
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
MarcW108 Comments: I have a working Type I clock and am in the process of getting it to keep time accurately. On Day 0, I set the correct time, on Day 2, the clock was accurate "to the second" from what I could tell at least within 1 minute. On Day 5, the clock is 2.5 minutes ahead. Is there an explanation for this? I am using my iPhone to check the time; the iPhone gets time updates from the network, which haftsuchscheinwerfer would think to be accurate. Has anyone experienced the same and know what to do about it?
March 22, 2011
  Followup from the Pelican Staff: It's a mechanical device, and these things were never super accurate to begin with. There is an adjustment screw in there so that you can adjust whether it runs faster or slower. However, I've found in the past that messing with the screw and trying to adjust the clock is a nearly impossible task. - Wayne at Pelican Parts  
fdonnie Comments: i have had 11 porsche's and the best advice is to replace clock with a quartz clock. pull guage out to the left of clockmuch easier to accessput rubber thin glove on,so you dont cut yourself on metal. good look DONNIE
March 16, 2011
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
amt230 Comments: Great article. I pulled my "type I" clock and found that the fuse was blown. But, when I manually wind the disc, it does not run, even for the few minutes that it should before it would need to electrically rewind itself. Do I need to clean? Where and with what? Thanks!
March 11, 2011
  Followup from the Pelican Staff: I would just clean the heck out of everything. These are pretty precise clocks - if you can't get it to work without damaging it, then a clock repair shop should be able to get it to work for not too much money. - Wayne at Pelican Parts  
Jan Comments: Opened up my 74 clock which is a Type 2. Everything looks good, except the miniature electrolytic capacitor driving the motor.That is the little blue can near the motor on the PC board. Looked like it had separated. Back then, they were notoriously unreliable. Replaced it and the clock is back in business. Replaced the other can while it is open. FWIW it is an AC motor. Drive is 60 Hz and about 6V. Draws about 13mA overall in operation.
Does not have the SCL5419AE, so I cannot help with the resistor question.
Jan
January 12, 2011
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Bjorn Comments: Hi, I have a VDO clock from a Porsche 911 from 1977, similar to the type2 from this article. It's bigger and has a different motor construction. I have a question concerning the electronics schematic. My clock is using a chip, named SCL5419AE, a crystal oscillator, 2 capacitors and one resistor. The resitor burned out, the color coding is unreadable. Does anyone know either the resistance to use or perhaps where to find the datasheet for the chip?
Thanks, Bjorn
January 9, 2011
  Followup from the Pelican Staff: I've never seen what you're describing, I would ask this question on our 911 Forums: http://forums.pelicanparts.com/porsche-911-technical-forum/ - Wayne at Pelican Parts  
michaelt Comments: My plastic housing has only two nuts and will not come off; the front arms move back when I pull on the housing
October 27, 2010
  Followup from the Pelican Staff: I would try to remove the outer chrome ring and see if you can get to the mechanism that way. I think I had one clock in the past that I took apart that had to be disassembled this way. - Wayne at Pelican Parts  
CZ Comments: I just removed mine from my 1968 911L. Before taking it apart I put it on my bench and tried powering it from a 12 volt regulated power supply, adjusted to 1a max. The clock promptly made the little "clunk" and started right up.

Inspecting it more closely I can see the positive connector is pretty dirty copper. My guess is after 41 years in the car, year after year, the copper oxidizes enough to make a bad connection.

So I'll let it run for a day, adjust the time if needed, clean the connectors, and put it back in. Should solve the problem for another 30 years or so.
June 5, 2010
  Followup from the Pelican Staff: There's also one or two connections on the inside that tend to become unsoldered over the years. - Wayne at Pelican Parts  
eddie Comments: do you know who will fix one of the type 2 clocks???'
December 12, 2009
  Followup from the Pelican Staff: It's usually a loose soldered connection. Palo Alto Speedo and Hollywood Speedometer both repair these. - Wayne at Pelican Parts  
Daniel Comments: Hi, it's Daniel again. I spoke too soon. My clock ran fine for about 4 hours then stopped and will not run on its own again? Do you have any suggestions? I thought maybe some of the fuse solder got into the mechanism but it all went round 3-4 times okay. I'm not sure what to do next. I look forward to your suggestions. Thanks Daniel
September 28, 2009
  Followup from the Pelican Staff: Try cleaning the contacts on the "automatic winder" mechanism. These clocks can be very finicky and difficult to get quite right. - Wayne at Pelican Parts  
Daniel Comments: Very reassuring notes, my 1971 300SEL Merc keeps time again. There was enough solder left to repair the fuse. The mechanism was a bit tight and would stop but I just kept it going manually for a few mins and it freed up enough. All the gauges are VDO the speedo needed to be repaird also. Thanks
daniel
September 26, 2009
  Followup from the Pelican Staff: Thanks for the feedback and additional info. Glad we could help.
- Nick at Pelican Parts
 
David Comments: How difficult is it to remove a clock on a 1977 911 that has failed and replace it with a rebuilt unit?
June 26, 2009
  Followup from the Pelican Staff: Very easy. Just get your fingernails under the rubber seal and pull out the clock. Then disconnect the light bulbs and electrical connections from the rear. On a scale of one to ten with ten being the hardest, this is about a .5 - Wayne at Pelican Parts  
pjp4 Comments: Hi, This is of great help to me as I did not know how to get the clock opened. Anyway, my clock has been broken due to high voltage spike. Would you know what IC is used on the clock PCB, please? Also, would you have some article on RPM meter disassembly and repair? Cheers, Peter
May 13, 2009
  Followup from the Pelican Staff: Shoot, sorry that's out of my scope of knowledge. - Wayne at Pelican Parts  

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