Yes, we have cruise.. - Page 2 - PeachParts Mercedes-Benz Forum

wolf_walker · #16 04-01-2004, 03:38 AM

Pulled apart, W123 shown.

Basicaly the plastic end has the metal case crimped in several spots, open it with a flat blade screwdriver by pulling the tabs back, or preverably with a pair of duckbill pliers. The innerds simply pull out, note the little foam brace.

wolf_walker · #17 04-01-2004, 03:39 AM

Backside of PCB. ALL those joints are what gets soldered. This is why it's a time consuming process.

wolf_walker · #18 04-01-2004, 03:42 AM

Top view. Note the two pairs of transistors. A cruise actuator pulling more joice than it should can and will blow these. As a rule a small transistor does not like to drive a motor directly, and these cars have this setup in several places. The rest is mostly IC's and resistors. Anything black and/or burnt here or on the back is a tell tale sign, but pretty easily and cheaply repairable.

wolf_walker · #19 04-01-2004, 03:44 AM

Finaly a view of a bunch of random stuff, including my home made spring compressor, or part of it, and my 1938 K98 Mauser.

wolf_walker · #20 04-01-2004, 03:51 AM

I'm going to go mail a few of you about sending me your dead amps in a moment, but I want to make it clear this is a hit and miss thing. I'm not an electronics guy really, just handy with a soldering iron and technicaly minded. I can build a wireing harnes for a car but a lot of the theory in electronics I never took the time to learn. I'm no substitute for people like that GDL link I sent you. If I solder up twenty more of these amps and none worked I wouldnt be surprised, if I got ten out of twenty I'd be more than content with the success rate. The solder joint failure is common but by far not the only thing that goes wrong with these amps, read that GDL page I linked. Good stuff there.
I'm willing to put some time into it for those who would like to not spend $200 or so on a profesionaly rebuilt amp, but I really suggest you buy a soldering iron, and possibly a lighted magnifying glass, and give it a shot.

Off I go to solder some more.

http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=soldering

#21 04-01-2004, 04:15 AM

Where exactly is the cruise amp located on a 126?

wolf_walker · #22 04-01-2004, 04:25 AM

Quote:

Originally posted by hotskillet
Where exactly is the cruise amp located on a 126?

Guess I could have mentioned that part, on the w123 and w126 it's under the drivers side dash, remove the knee cover, and it's mounted to the left of the steering column/brake pedal assembly with the connector faceing down. There's a 10mm or so bolt holding it in, no need to fight with the screws. There is probibly another wireing plug attached to it somehow that isnt involved, just unclip it and move it out of the way.

ALSO NOTE, IMPORTANT!!!
Most profesional rebuilders or that want a core unit, will not accept one that's been opened. Dead amps are not hard to come by, but always note your part number on your original for future reference.

#23 04-01-2004, 11:18 AM

This sounds like a cheap fix, thanks for the idea.

wolf_walker · #24 04-02-2004, 02:27 AM

Well, of my initial batch of six dead amps, three are working pretty darn well. Probibly not perfect, but absolutly usable.
I think it'd be well worth paying $5 a pop for a few now and then if these success ratios are not a fluke.

After observing and reading a bit, this amp and system in general is just SO mercedes it hurts. It probibly worked EXTREMLY well when everything was new, but the trouble is, all electrical componets, espicaly after twenty years, there values change. And the way this thing works those skewed values contribute to all sort of little things.

I'd like some post 86 amps to play with, there updated in a few nifty ways. I had an 86 that was notably different internaly, unfourtunantly it was not one of the three that woke up and worked.

Overall this was a fun project, I plan to keep at it. MAN a working cruise is nice..

BoostnBenz · #25 04-02-2004, 11:35 AM

I think the W123 DIY page may be getting a few links longer soon.

I like this as well:
http://gdl-online.com/bulb.html

81Wagon · #26 04-02-2004, 01:50 PM

Do you just solder right through the plasticy film that covers most of the back of the circuit board? I had my amp out a couple months ago but was afraid to solder through that. I might have to pull the amp out and resolder it now...

Rafi · #27 04-02-2004, 02:00 PM

wolf_walker is the K98 Mauser required item for W123 ownership or does it come with the car?

wolf_walker · #28 04-02-2004, 04:25 PM

Quote:

Originally posted by Rafi
wolf_walker is the K98 Mauser required item for W123 ownership or does it come with the car?

I think they issued them with the early models, but it's strictly optional with a w123. However they do compliment each other's respective traits nicely though.

wolf_walker · #29 04-02-2004, 04:27 PM

Quote:

Originally posted by 81Wagon
Do you just solder right through the plasticy film that covers most of the back of the circuit board? I had my amp out a couple months ago but was afraid to solder through that. I might have to pull the amp out and resolder it now...

I have not run across a plastic film yet, but I have seen something simililer on other devices in the past. Could you post a photo, or the year and such for the model with that amp?

I don't believe one could solder through it, must be a way to remove it.

lietuviai · #30 04-02-2004, 05:06 PM

Wolf, the CC in my car works but it is plagued by the infamous surging. Do you think the surging could be caused by a bad amp as well? I have checked everything else including the tail light bulbs but not the amp. I have pulled the amp out to just look it over but I haven't opened it up.