[W126 Coupe] Strange instrument cluster behavior

[Dick Spellman]

Markus:

The capacitors on the clocks just dry out with time.  So, replacing with 
another clock will eventually result in the same dead clock scenario.

Perhaps you can review this write-up and see if you want to tackle the 
repair or just send the entire IC to a VDO repair outfit.

Good luck,

Dick

<http://web.mac.com/dakota/Mercedes/Projects_files/126_IC_CLockRepair_1.pdf>

Markus Meyer wrote:

> Well, the speedo pod must be the problem.  I took the original cluster 

> now, switched JUST the speedo pod with another one, and everything 

> worked.  So the common thread with problems appears to be the speedo 

> pod, because with it, all other parts even when known to be working 

> don't work right, but when a different speedo pod is in there, all 

> other pods work ok (even the original ones).

>  

> Now to figure out how to swap a known working clock with the bad one 

> in my existing tach pod.....or to swap out just the tach and leave the 

> good clock in another pod....but after removing screws the clock seems 

> to be sodered in at the back, and the tach of course has 3 wires 

> sodered in.  Not sure what is easier to change out?

>

> Markus Meyer

> mfm at meyerprobateproperties.com <mailto:mfm at meyerprobateproperties.com>

> www.meyerprobateproperties.com <http://www.meyerprobateproperties.com/>

> Meyer Probate & Properties, LLC

> 484-919-9762

>

>

>     -------- Original Message --------

>     Subject: Re: [W126 Coupe] Strange instrument cluster behavior

>     From: Markus Meyer <mfm at meyerprobateproperties.com>

>     Date: Sat, September 15, 2007 8:42 pm

>     To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>

>

>     Toasted the cluster you say - which part - just the speedo pod?  I

>     found it strange that when I first swapped out only that one pod

>     with oil/temp/gas/vacuum with a known working one, it also acted

>     funny.  Then when I put the other complete cluster from the 560 in

>     which was known to be working, everything worked fine (except of

>     course tach and speedo are off).  I may try putting a good known

>     working speedo cluster into my original cluster to reuse the "4

>     pod" and tach pod to see if they are okay.  I'm just surprised I

>     would have fried the speedo pod and nothing else, but so far thats

>     wh at it looks like.  Guess with that damned clock not working I

>     "forgot" that wire was hot dammit...I tested all the connections

>     several times and looked for fried wires and the such before

>     putting that complete known good cluster in and found nothing

>     obvious, and no fuses blown, etc.

>

>     Markus Meyer

>     m fm at meyerprobateproperties.com

>     <mailto:mfm at meyerprobateproperties.com>

>     www.meyerprobateproperties.com

>     <http://www.meyerprobateproperties.com/>

>     Meyer Probate & Properties, LLC

>     484-919-9762

>

>

>         -------- Original Message --------

>         Subject: Re: [W126 Coupe] Strange instrument cluster behavior

>         From: Dick Spellman <spell.yy at verizon.net>

>         Date: Sat, September 15, 2007 8:13 pm

>         To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>

>

>         Whew. Marcus. That wire you pulled off of the lug on the clock

>         module

>         is 12 volts hot at all times. The spark you describe would

>         have been

>         making contact with the cluster backing which is a ground

>         path. So

>         that's a dead short brief as it may have been.

>

>         I'd go over everything one more time and see that the

>         connections are

>         correct. And be careful with that hot 12VDC lead. You may have

>         toasted

>         the cluster, not sure.

>

>         Dick

>

>         Markus Meyer wrote:

>         > Hi guys,

>         >

>         > I have a question about the instrument cluster. I was taking

>         the

>         > cluster out to see about painting the needles. When taking

>         the wire

>         > off the clock it sparked because as I pulled it off I guess

>         it touched

>         > to the pin again. Anyhow, after putting it all back

>         together, the

>         > temperature/gas gauges were maxed out and the oil pressure was

>         > minimized. And the dash lights would go out when I started

>         the car,

>         > go back on when I shut the car off.

>         >

>         > Now this is what gets weird. I then installed a known good

>         working

>         > cluster from another car. Everything worked fine. So now I was

>         > totally confused. So I then swapped just the speedo pod from

>         the

>         > original cluster to the second cluster where everything worked.

>         > Again, the strange behavior! Put the second speedo pod back

>         in the

>         > second cluster, everything fine.

>         >

>         > So....what happened? Why would the speedo cluster cause the

>         > temp/gas/oil pressure/vacuum cluster to act funny? Is there

>         a fuse I

>         > blew somewhere I can' t find/see.

>         >

>         > And I can't just use this second cluster as is because one

>         is for a 6

>         > cylinder and the other is for an 8 cylinder and the speedos

>         and tachs

>         > are calibrated differently. I just want to make sure I

>         didn't mess

>         > something else up somewhere I'm not aware of...

>         >

>         > Thanks,

>         >

>         > Markus Meyer

>         > mfm at meyerprobateproperties.com

>         <http://email.secureserver.net/pcompose.php?aEmlPart=0&type=reply&folder=INBOX&uid=2206#Compose>

>         <mailto:mfm at meyerprobateproperties.com

>         <http://email.secureserver.net/pcompose.php?aEmlPart=0&type=reply&folder=INBOX&uid=2206#Compose>>

>         > www.meyerp robateproperties.com

>         <http://www.meyerprobateproperties%0A%20.com/>

>         <http://www.meyerprobateproperties.com/>

>         > Meyer Probate & Properties, LLC

>         > 484-919-9762

>         >

>