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Discussion Starter #1
Ok so pretty quick here. My cluster has power and all the warning lights work, but the gauges do not. Is that a symptom of the capacitor failing or would that be total darkness? I have read that they go bad, but havent found any real trouble shooting threads. Just want to make sure before I take my board to the local tv repair guy and have him replace the capacitor.
 

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Is this on your 1999 S500? Or ?? The later gauge clusters are less prone to failure than the early mechanical odometer models which had failing caps, transistors, etc. The fact that all the gauges quit indicates it may be a common issue between them, such as a bad solder joint, and not caps at all. Did they all quit at once, or gradually over time?

Frankly, it may be cheaper to get a used working cluster from eBay or a Pick & Pull wrecking yard.

I'd PM MAVA, and get his input. He has a lot of knowledge on repairing the various electronics on W140s.


Jon
 

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First the tach stopped working the the backlights were hit or miss then after working on the car for 4 months. All the gauges stopped they came back for 1 second then never again. I took it apart and I tested the 3 caps on the board and they all show a reading that is not infinity. I did find one thing that looks curios. the middle post on this chip thing is not connected to the board. [URL=https://s1190.photobucket.com/user/hanly2/media/IMG_20190912_112725.jpg.html][/URL]
 

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That lead looks like it's clipped, not melted. Can you read the part numbers on it? Might be able to tell from the data sheet what that lead is for.

There may be a surface mount fuse somewhere on the board that blew. Since the board doesn't appear to be marked, it would be hard to find if that's it.

Jon
 

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@MAVA any ideas what I can check?
@MAVA any ideas what I can check?
I'm like 8hrs away from my 98 which has the same cluster to give you a where to test. In two weeks I will have access to my car to look at that if you can wait.

9 times out of 10 it a capacitor that failed. That may caused another part to fail.

I worked on older clusters and their is a fuse soldered on the board, so the 99/98 will probably has the same. Now Jon is correct by the data sheet, and what I have done in the past is looked up the larger semiconductors as the probability that they are voltage regulators more often true, yet from the data sheet info I find the voltage out, and find the voltage measurement that feeds the entire cluster. That is the way to trouble shoot the cluster.

On these cars, the cluster is feed by several 12v feeds, and probability of the connector losing a wire can happen, so you may have to measure the DC voltages at the connector from the Mercedes data.


Hover the mouse over the "page numbers". Look at the diagnostics info sections, but look at the electrical section too.

Hope it helps

Martin
 

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Discussion Starter #8
The one part of the connectors that is weird is the one is like 16 pin and only 1 wire lol. Whats that about? Thinking about taking the cluster over to the tv repair man and see if he can test the capacitors.
 

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Yep, that is correct with the one-wire in those clusters... The old school clusters do the same, but they have four connectors, and one has a few wires.

Martin
 

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Discussion Starter #10
I bought a used cluster from ebay with a cracked screen. I swapped them out and the new one worked except for the gas gauge. Upon further inspection I saw that the gauge needle was under the pin lol Quick change of the screen and all is good now. So now I have an extra cluster available for parts.
 
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