Clock repair

I don't know if yours will fall into the range of clocks they work on, but they did good work on my speedometer ('82 380 SL) for a reasonable price:

Google and you'll find a site that tells you how to DIY. Usually a couple of capacitors open.

The clock is easy to repair

Its the two capacitors (both same) on the clock pcb, which is easily accessible if you remove the instrument binacle. The capacitors dry out (age), and need replaced. A couple of new 100uF 35V electrolytics will be needed. Just un-solder yours and fit these. Remember they are polarity sensitive so get them in right way round, and the job is a good un'.

It's a 1/2 hour job. Do a www search on Mercedes clock repair and you'll find some more info and maybe pictures. Don't worry if its not your series car you find the info on, they are all broadly the same (analogue clocks).

Cheers... Rob.

"tapdrive" wrote:

I just did mine a few months ago. The clock died after sitting at the airport parking lot for 10 days in 95 deg temps. Guess you can expect that after 25 years! When I looked at the clock/tach combo, I could see what looked like a bad cap, but I was gonna send it out to be fixed. Then I came on an article on the internet that described how to fix it. I've attached it below. If you;'re reasonably skilled, it's a snap. Just follow the directions. The only things I would add are any 100uf cap of the same form factor with a voltage rating of 16 volts or higher is fine. Got mine at Radio Shack and think it was 35V. While you're there, also pick up some solder wick, which is a copper braid that you can place over the PC board holes and heat with a soldering iron to wick up the solder out of the holes. Let us know how you make out!

3=2E Doug Quance Dec 29 1997, 3:00 am show options

Newsgroups: alt.auto.mercedes From: Doug Quance - Find messages by this author Date: 1997/12/29 Subject: Re: 300E Clock Repair Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse

Dick Hughes wrote:

Dick: Here is a procedure from a fellow enthusiast. Clock Repair Procedure

It is my understanding that most late model Mercedes-Benz clock failures are due to a bad capacitor (or capacitors) on the back of the clock. You do not have to be an electrical engineer to do this procedure. In fact, the electronics on the clock consist of only 4 or 5 components, so ID is easy. With this in mind, I repaired my clock last weekend in my '87 300SDL. The procedure is as follows.

1=2E Go to Radio Shack and buy (2) Part Number 272-1028 and also purchase

a small low-wattage soldering iron, along with rosin-core solder. And, if you don't have a minature screwdriver set (flat blade), now's a good time to get one. [The capacitors in my old clock had the numbers 100 and 16 on them, and the Radio Shack numbers are 100 and 35, which work fine.]

2=2E Go to an automotive paint store and buy a bottle of Meguiar's Plastic Cleaner and Meguiar's Plastic Conditioner. 3=2E [Note: your Mercedes-Benz automobile may be one where the instrument

panel can be pushed out from the rear after simply reaching under the dash. If so, then steps 3, 5, and 6 can be omitted.] Fashion a non-OEM factory instrument panel (IP) tool out of a a thin coat hangar by doing the following: a. cut the long bottom strip to use as the tool. b. put a 75 degree bend at one end with a couple of inches of extra wire. c. cut the bent wire about 1/4 inch from the bend with a pair of wire cutter and leave a "sharp" edge with the cut. At the other end of the coat hanger, fashion a circular handle out of the excess, leaving the whole tool around 4-6" in length. [Please note that there may be a problem with uncooperative IPs that requires a stiffer tool. In such

cases, use an Allen wrench (~ 1/8") instead of a coat hanger and use Visegrips

to hold it.)

4=2E If your car has a telescoping steering wheel, fully extract the wheel's reach. (If it doesn't have this feature, you can still probably do this

without removing the steering wheel by judicious wiggling. Now confirmed for an '83 300SD without telescoping wheel.)

5=2E Using your instrument panel removing tool (which you built with pride), slide the tool in between the IP and the left side of the dashboard at the 10 o'clock position. Do this with the hook of the tool parallel to the mating surface. Push the tool all of the way in. Turn it 90 degrees to the right. Grabbing the tool's handle, pull the left side of the IP out carefully,

until the tool's hook just clears the dashboard.

6=2E Repeat step 5 on the right side at the 2 o'clock position, but turn tool 90 degrees to the left this time. 7=2E Put a large clean towel on your workbench. 8=2EYou should now be able to grab the IP by hand. Pull it out at the right and start unplugging things. [Note: your oil pressure gauge may have an oil

line from the engine. Be careful when removing, cover with a rag and a rubber band while disassembled, and don't start the car during repair.] You'll want to mark the bulb assemblies with numbers if they are not already marked (mine were -- I'm not sure if from factory or not.). Unplug everything and remove the IP from the car to your bench.

9=2E Lay the IP face down and carefully note ordering of instrument "pods." Mine had three. Remove the pods carefully and place in a non-scratchable location.

1. Using the Meguiar's products (which are incredible products and no,

I don't have an affiliation other than being a satisfied customer), clean

and condition both the inside and outside "glass." It'll take a while, but

you'll be pleased with the result. Somehow, the inside glass accumulates dirt

over time.

1. Plug in the soldering iron to let it warm up.
2. Now, to the clock. The clock, at least with my SDL, was part of a tachometer/clock combination. The clock's hands remove easily with your fingers (notation of positioning is unimportant at this point), but the

tachometer's needle is better left alone.

1. Remove the three flat screws on the front of the combo which hold the tachometer to the instrument facing.
2. Put the combo face down on the towel. Remove the rear screws which

hold the tach and the clock. After removal, you should now be able to separate the combo enough to remove the clock as a component to work on.

1. Don't forget to "save" the rubber gasket on the back of the clock for installation at the proper time. (I forgot to re-install mine, but I don't think that there would be any adverse effects unless you're anal retentive.)
2. Place the clock face down on the towel. Find the capacitor(s). They are probably about 1/2 inch long and round. (As I remember, the only other

electrical components are: 1 resistor, a crystal, and an integrated circuit). Note the direction of the capacitors (there should be a "+" on one end.)

1. Using the soldering iron, and a large minature screwdriver for leverage, "de-solder" the capacitor (or capacitors), placing the screwdriver blade between the capacitor and the circuit board for leverage. You'll have to do this in stair-step fashion, since the solder will probably harden before you can remove the whole thing at once.
2. After removal of the capacitors, "clean" the wire holes by heating the solder and shaking it off.
3. Install the new capacitor(s), without cutting their "leads." Note that the Radio Shack replacements have a "-" instead of a positive marking direction.
4. Cut the leads at the edge of the solder joint.
5. Reassemble and reinstall eveything. When putting the clock
6. Let me know if you complete this successfully, so I'll know that I haven't wasted the last 30 minutes typing this up!!! .

Or for repair Im told these folks can help. Overseas Speedometer in Austin, Texas 800-444-0292 who promised to repair (he warned that some may not be repairable) for ~$65.

-- SANT=C9 Doug Quance

87 300TDT 'Phoenix' member MBCA

Consciousness: That annoying time between naps. Confucius say, Baseball all wrong. Man with four balls cannot walk.

90% of being smart is knowing what you're dumb at.

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