W123 VDO Cruise control repair series part 3: Amplifier repair

[@trythistv]

Here are some links to products we used in this video on amazon in case you want to try this, purchasing from these links may earn us a small commission that helps us keep doing videos like this one: Rosin core solder: amzn.to/2YdjPtw Solder wick: amzn.to/2VQG86O Portasol soldering kit: amzn.to/35fpMaK Portasol individual soldering iron: amzn.to/3eZNgFv Capacitors I used were ordered from Mouser, with the following part numbers: 22uF: 647-UVZ2A220MED1TD 10uF: 598-106TTA100M 2.2uF: 598-225TTA100M Possible alternative capacitors, I have not tried these, but they are the same on paper: 22uF capacitors: amzn.to/2xnz48c 10uF capacitors: amzn.to/2Si9pVu 2.2uF capacitors: amzn.to/3bQCDTk

[@davidjames9506]

I am 84 years old and have been working a 100 Sadie's cars since I was 28 and this guy is remarkable and very helpful and I appreciate his video

[@trythistv]

Thank you so much for your kind words! Its nice to know that these videos are useful to the community of Mercedes owners and enthusiasts.

[@erlowther]

Trythistv, Followed your DIY steps on how to troubleshoot my 1985 Mercedes 300d cruise control issue. Quit working about a month ago. Got to the point in your steps where the issue just had to be the magic box. Ordered the needed capacitors from Mouser as you suggested. Switched out the old caps with the new ones and took the car for a test drive. Still no cruise control! Only steps I skipped was the laborious task of removing the lacquer from the board and then spending an hour or so touch soldering each and every solder point on the pc board. Needless to say, I was not optimistic about the process. However, took the car for another test drive and there it was. CRUISE CONTROL once again! Bottomline for anyone attempting this fix: DO NOT SKIP the point solder steps. Painful, but well worth the extra effort in my case. Thanks for the detail and hard work you put into this vid. Super appreciate it! Ernest in Lexington, KY

[@trythistv]

Awesome success story! Thanks for sharing! The document available for download on the website (trythistv.com/cruise-control/) has pictures of what some of the solder joints end up doing. Its very hard to see without some kind of magnification, Touching up every joint is the easy way.

[@jondaniell5481]

One of the best tutorials/troubleshooting videos I have ever seen. Thank you!

[@trythistv]

Thank you! It took quite some time to learn how it all works, but it sure was satisfying when the cruise worked after all this!

[@brandon3547]

Thank you so, so much for this. I've repaired the cruise control in my W124 and my sister's W123, as well as the ACC temperature regulator box in her W123 with your video on that. Original monovalve still working great (fingers crossed lol). Saved me 100s of dollars. BTW if just replacing the caps on the cruise control board doesn't fix it, try reflowing all the solder joints as that made my W124 cruise work flawlessly with no surging.

[@trythistv]

I'm so glad to hear your successes! Its really nice having all those little creature features working properly. I need to pull my climate box back out and reflow all the joints, it worked amazing for 4 or 5 months after replacing the caps but has gone back to some erratic behavior.

[@GreaseAndGravel]

Man, this is my new favourite channel!

[@trythistv]

Thanks! I'm glad its proving useful for you!

[@unaeruditi]

Thank-you so much for this video. You have saved me/us so much value/money and as a DIYer . I always wanted to get my cruise control running in all of my mercs over the past 25 years w/o spending 1,000+ on it. Now I finally get to have cc on the 240d I have now. Please keep up the superlative work! Sir

[@trythistv]

Glad to be of assistance! These cruise controls can be quirky and very troublesome, but to have the little fiddly comfort things working transforms the whole car!

[@moosekg]

Thank you very much. Although the tempostat module was built into a '93 previa, everything was almost identical. The only difference I saw was at the connector at the actuator (round type of plastic), but all the colors of the cables were the same, so based on your word guide I could easily comprehend. All the things were tested, just as you advised, the issue on my vehicle was 2 faults. On the ground cable it became so much corroded, I had to make the cable shorter and ground it in a different spot and of course all of the solder joints were reflowed. Much appreciated your help, finally a feature I can use and would have never dreamed without your guide to be able to repair it! You rule!

[@trythistv]

How interesting! I guess we may never know how many vehicles used a similar cruise system, VDO was everywhere back in the day it seems! Glad you got it working, keeping unique older vehicles around is one thing, keeping the creature-features working is above and beyond!

[@rce7476]

Thank you so much for all the details, it's greatly appreciated!

[@johnpaulmellish7266]

Thank you for the 3 part video, very helpful, saved me a lot of money. I tested all circuits which were fine, so left with the amp box, I replaced the capacitors as in the video...... and smooth cruise control again, happy days! Mine was from a Mercedes 310d 1990 which had 6 capacitors. Thanks again.

[@trythistv]

So happy to hear that the videos helped you out! There is a lot on these cars that isn't necessarily hard to repair, it's just somewhat vague and not well documented.

[@johnpaulmellish7266]

@@trythistv Yes youre right, not much documented, good to get it working as the 310d is the chassis for my Hymer motorhome, nice to keep all the original parts working on it, Road trip across Europe next year... in cruise control ofcourse, :-) thanks again.

[@trythistv]

@@johnpaulmellish7266 Oh you NEED cruise working on a motorhome, any sort of long trip is miserable on the legs if you've got to hold the throttle the whole way! I helped a friend move from MA to GA, just over 1000 miles, and the moving truck we rented wouldn't engage the cruise above 55mph (speed limit was 70+ the whole way) and by the time I was done driving the last leg of the trip I couldn't hardly walk anymore my throttle leg was so stiff.

[@johnpaulmellish7266]

@@trythistv Hi ya again, well went to use the motorhome today and no cruise control at all, seems very strange as it worked perfect before. will run the tests again.

[@johnpaulmellish7266]

Had a problem with the cruise control again. After long hours traced it to a Zener Diode on the speed signal,replaced it and BOOM, cruising again. I think all the times I had the amp plug on/off it snapped. It was hidden under black electrical where two wires joined. For reference its a BZX55C 3V9 500MW ZENER DIODE, Cost 4 pence

[@Kates-dead-goon]

Thank you. Excellent information.

[@trythistv]

Glad it helped you out! There isn't a ton of info out there on these

[@QsTechService1]

Good to know thanks for sharing I'm definitely going to recap mine I can imagine 40 years later how can the capacitors even be good lol

[@trythistv]

The solder joints and caps are usually all that goes wrong with these amps.

[@magdaa1575]

You are the best Thanks

[@patrickphippspa584]

Well hey there buddy! Glad to see another wonderful video! I'm going to sell all of my W123s soon. I have a super low mile 300TD motor on an engine stand, a 83 240D with less than 60K original miles and two 300TD wagons. Wish you were closer, this is probably a collection you'd like to have to add to your collection. Hope all is well there buddy!

[@trythistv]

Oh man, do I ever have a soft spot for wagons too! Quite the gold mine you've got I'd say, low mile engines/cars are hard to come by! I hope your w123s have served you as well as mine have done for me, I'm sure they will bring smiles to the new owners faces as well. Hope you're staying safe with everything going on!

[@larrytaylor8641]

I would like to see some pics and more info on your collection.

[@rationalfunction3]

This is a great video. Thanks

[@trythistv]

Thank you very much! I'm glad it was helpful for you!

[@Brianbuilds123]

Super great video. Thank you. Where did you find the capacitors?

[@arvidkarlberg5845]

Great video! Do you know if the same capacitors in the same amount should be used to resolder the W124 amp? I have a late model 1994 E320.

[@trythistv]

I had a W124 amp somewhere, and it was nearly identical, but may have had less capacitors if I recall correctly, if you remove it and send me some photos of the insides to tom at trythistv dot com I'd appreciate the extra info, and then we can confirm what capacitors there are!

[@teesaeed6529]

Thanks for sharing in details. would like to know what could be use to remove the rust from a circuit board, without having any damage to the electronic? Have a instrument cluster to work on and found almost every connection in it is surrounded with rust. A big box hardware store employee suggested RUST-OLEUM rust dissolver jelly, any experience with the product or any alternative suggestion please

[@trythistv]

The rust dissolver jelly is good stuff but I would be hesitant to use it on a circuit board, I believe it is typically phosphoric acid, which might have a tendency to eat the copper on the circuit board. I would try to get a purpose made product like deoxit (amzn.to/3Qz6jux) and a small brush, I know people that work on amps and old school audio stuff likely have the right stuff so maybe try hitting up a local guitar place or if you know anyone that works on that kind of old school tube amp type stuff they could probably point you in a better direction than I can.

[@teesaeed6529]

@@trythistv Thanks a lot will try to look further for some alternative product.

[@livium2002]

Awesome content, as usual !

[@trythistv]

Thank you, Thank you! I'll keep putting out everything I can, these cars are great when everything is working like its meant to!

[@highplainsdrifter842]

Hello I have an old early 90s mercedes hymer campervan, it has a VDO cruise control just like the one in your video and its wired up to a mechanical speedometer, the cruise control does not work, and when I'm driving along if I move the stalk a strange noise comes from behind the dashboard, the noise sounds like a regular popping sound, or like something is tapping/knocking, a bit like a clock but slightly faster, so I found the wiring diagram for the cruise control and according to that, the only thing that could be behind the dashboard is the amplifier, so my question, is it possible that the amplifier could be making this noise?

[@trythistv]

That is odd, I would certainly pull the amp out and check out the insides, it could be capacitors are bubbling and coming apart.

[@glotube1028]

Sweet! Nice job! I can’t wait to do mine! Now I just have to figure out where to get the capacitors. I’m a electronic idiot.

[@trythistv]

I put some part numbers for Mouser in the description, they had pretty good prices on the exact ones I used, Amazon also had caps that were correct in the ratings but not exact as far as fitting perfectly, but would work just fine

[@pinzgauernorcal]

i just did mine it worked great !

[@trythistv]

Sweet! I know my wife is absolutely in love with the cruise. She was never a huge fan of my old diesels but she was so excited the other day when she got home how nice the cruise worked and how great the car drove! I've got more videos in the works, I'm just slammed with work with my business right now, I'm trying to get a little free time to get into one of the new projects I have for the blue car!

[@policeofficer94]

Perfection! Thank you! My rust free 85 300TD has over 380,000. Rheostat trouble shooting? I lost my dash lights. Also lost my backup lights. 4-speed manual trans Thanks

[@sisyphusofmorons]

You can bridge the two lines that go into the dashlight dimmer, it will then be at full strength all the time.

[@cliveedridge2350]

great video i managed to get the control unit out ,on trying to remove the electrical plug i must of pressed something by mistake, as all the pins started to come out of there housing ,so now i need to find out which pin and coloured wire go in which hole, they are numbered on the housing 1-14 ,hoping you could help tom

[@trythistv]

I will grab some photos of that connector, and pop it apart so the color codes are visible and add that to the document on the website likely over the weekend if I can remember.

[@cliveedridge2350]

@@trythistv Hi did you manage to put a copy of the wire codes on

[@trythistv]

I just did it, I actually took the photo like I promised over the weekend, but then never got around to putting it together. New document is live at trythistv.com/wp-content/uploads/2022/08/VDOCruiseAug2022.pdf

[@bigbuick716]

If you’re looking for another project...how about teaching us how to diagnose and repair the tach. Mine is dead...just sits on zero. Thanks again for the very informative and clearly presented topic. You’ve got me convinced I can do this myself!

[@trythistv]

Funny you mention that, I'm currently on the hunt for a instrument cluster to play with. Been scouring the usual online places, I should check junkyards near me but so many of them only hold on to cars more than about 10 years old for a week before they crush them, which is incredibly sad. I missed a pristine 240d with a 4 speed that was there one week and gone the next before I had a chance to see if they would sell it whole or at least snag the trans stuff for another 4 speed swap. Partially to play with the tach and potentially build a better tach amp, and partially to play with the other stuff going on with the gauges to understand how they all work and perhaps make some videos on repairing some of the common issues. I have repaired the tachs on both my cars, and I have a spare tach amp (little black trashcan thingy) I've been thinking of doing a video on,

[@bigbuick716]

trythistv I will check locally. As recent;y as two months ago there were a couple of w123s in a junkyard here. I got several parts off one (power antennae, sunroof cable and track parts, and a cruise amp) I will pull the instrument clusters on them if there. I don’t know what the tach amp looks like or where it is located. If you can let me know I will check for those as well. 😁

[@bigbuick716]

trythistv UPDATE There are several w123s in the PULLAPART yards in ATL where I trade. Can you tell me what years and models of instrument cluster you need?

[@myid9876543]

Check on the tach amp in the engine bay near the cruise actuator. Pull the cap and module off, remove the module from the cap by pulling it out and wiggling. Push napkin or a receipt or something in the cap and reinstall the module. Enough paper to compress the module down and w123 tachs start working again.

[@trythistv]

I'm sure I responded the other day. For some reason it is not showing up now, maybe I clicked something wrong. I'm basically looking for any w123 cluster that has a tach, I think all the turbo models had a tach, I'm not sure about the n/a models or the 240ds. I want to set up a little test bench to poke and prod each gauge and better understand how they work to better be able to repair and explain how to repair each function.

[@MichelDOSI-u6m]

Hello, your work is great. Do you have the references of the 4 power transistors? Thanks for your help

[@trythistv]

I do not off hand, but I do need to pull apart several that I have for inspection, I'll get whatever info I can if there are legible labels and report back to you!

[@MichelDOSI-u6m]

@@trythistv It's good

[@MichelDOSI-u6m]

BD437 et BD438

[@bigbuick716]

YES!!

[@frostshock13]

If anyone comes across this and mouser is out with giant lead times or don't want bulk, go enter the part numbers in Digi-Key. It was only place I could get like low amounts at good price in stock.

[@trythistv]

Most definitely! I've used Mouser and Digikey quite a bit, I've heard Newark and Arrow also are great to deal with, but haven't personally tried them. What I really need to do is find time around my work to separate out the psychotic amount of capacitors I've ended up with and start giving away bundles of enough to fix an amp like I planned on doing. I have a whole rubbermaid container that is like 14"x8"x6" full of various things I bought massive amounts of because it was the only way to get them that I had intended to make little gift baggies and mail them out in some kind of giveaway thing, I'll still get to it sometime!

[@frostshock13]

@@trythistv Yeah, I like check the mouser ones and one was like 48 week lead time.. then the amazon ones are like qty 50 or like not the right style. I didn't want to end up like that with 100's of caps I won't use. Hopefully, this fixes up my cruise, it still works but it is very unsmooth, jerky and does weird accelerations. 13 bucks sounded better than 198 for rebuilt.

[@bobbycray7007]

Great videos. I'd like to ask you tho, before i go through the testing, which I have never done, would you have an opinion as to why my cruise is bucking. In other words it goes on, then when I set it, it starts to rock in a way that it seems the gas pedal is pumping on the gas lightly. Would you consider this an issue with the actuator or the cruise box itself?? Just looking for a starting point. I you think it might be the cruise amplifier, I may just buy another one rather than soldering capacitors. Same with the actuator. I feel it would be easier to just replace them than test, bc with my luck and inexperience, I'll probably short something out and make things worse. Thanks for your advice.......T

[@trythistv]

I'd suspect that is the amp, but it could also be the "feedback" circuit in the actuator has a spot that is worn through, does it surge at any speed you set it at or just at the most common speed limit? If it's at any speed, it's gotta be the amp in my opinion. If it only surges at one speed then it's the actuator. The worst part with buying another amp is at this point they're all ancient so it may not last very long. There are a few people around that rebuild them though. I do believe there is a gentleman over on the peachparts forum that does quality work, I'll see if I can find him and post a link to the thread later today

[@bobbycray7007]

@@trythistv Yes all speeds.I just located another one on ebay where the car had under 100k miles. For $30-40 it's worth a try. But rebuilding might be a better option since I went through the trouble to take it out already. A couple weeks ago I bought one on ebay and when I plugged it in it did nothing at all. Put the original back in and it pulsed again. If you can find someone who rebuilds for me I'd truly appreciate it indeed. Thanks for your reply too.

[@DangerDIY]

Great video. I don’t have a cruise control on my 300D. I don’t know if it is possible to retrofit one or not. But I did like the video. Thanks.

[@trythistv]

They were quite common, perhaps some euro spec models or such didn't have it, I haven't seen one without, but I learn something new every day! I would think it would be possible to retrofit one easily enough, I might even have a spare actuator and linkages on the spare parts engine I've got

[@DangerDIY]

@@trythistv Yes. My car is "special" as I was told it was imported from France. I've had it for about 12 years, but just recently decided to turn it into my daily driver after garaging it, and then neglecting it for a few years. I believe it has many small differences; for instance, no turbo; it is naturally aspirated, my AC system is different, location of stuff is a little different too. I will have to post a video of under the hood as I don't have things in the same places as your car. For other examples my heater/ac blower fan and motor is different and I am pretty sure my instrument cluster is missing the connection for the cruise control as well. My old one seized up and I ordered the part without checking to get in something totally different (what you have in yours) for my car. I ended up just tearing the replacement apart and salvaging the motor and rebuilding the old enclosure with the new motor (which unfortunately wasn't the exact same size). It all worked out in the end though, and I suppose that is what is important. I am going to see if I have (and am hopeful that it is) the same 4 and 5 vacuum plugs behind my climate control panel; that air re-circulation mod looks awesome. I don't have the fancy buttons with my climate control so I am not sure what I am going to find behind the panel.

[@DangerDIY]

@@trythistv I wanted a closer look and so I went by a local salvage yard and looked at one installed in a Mercedes and uninstalled it and took it home. They only charged me $35 for everything (yay!) I am going to see if I can get it going in a down the road project. I definitely will be referencing your video when I do though. Hopefully this will be something I get to this year. Next on the list of KZbin Projects is to finish my generator hook up (not as fancy as your 3 cylinder diesel!) and then I think it will be time to build a CNC controlled plasma cutting torch table.

[@dennisstrawley2314]

Fantastic Tutorial. Can you tell me how many of each capacitor you ordered from Mouser from your above parts list?

[@trythistv]

I do believe it was 2 of each needed, I ended up ordering like 100 of each because it was cheap. I keep saying one day I'm going to figure out how to run one of these giveaway drawing websites and start giving away little packs of cruise capacitors, fuel filter o rings and some of the spare items I've aquired like that. In the meantime, I believe it was 2 of each needed, I will double check and let you know for sure tomorrow though!

[@maksimsayevitch6712]

It's a great video. However, I have an early version of CC on my 300CD from 1980. It looks different and has only 12 contacts on the connector. Actually 10 cince there are no cables on pin 1 and 2. Please help.

[@trythistv]

I will have to update the PDF on the website with a table of the pins for the early w123s, but in the meantime, give this a try: Pin 3 is Actuator control (I believe the early w123 use a different style actuator so there is no solenoid engage) Pin 4 is for the decel position of the stalk Pin 5 is 12V battery voltage Pin 6 is Brake switch Pin 7 is Another actuator control Pin 8 is On-off on the stalk Pin 9 is Accel on stalk Pin 10 is Resume on stalk Pin 11 is Speed sensor input (I'm currently unsure how to test) Pin 12 is Ground

[@domingosiglesias9186]

Goodnight! I'm having problems with my Cruize Control. It's the same as what you're explaining about the concert. Turns out it burned out the diode that is connected to deceleration. This is the one I marked in blue on the photo. I would like, if possible, you to check on your board which specification of this diode marked, in blue color. I would appreciate it if you would send me a detailed photo of him with the number. Thank you in advance.

[@trythistv]

Hello, I've taken a photo, hopefully it is clear enough, looks like that little blue diode says 48 on the top, but perhaps you'll be able to tell more: trythistv.com/wp-content/uploads/2021/12/IMG_2174.jpg I'll also send you an email just in case you don't get notified of this message!

[@trythistv]

I've removed the diode, I will have to take photos of it, but at first glance it looks like it says BA148 and has a little triangle in a circle for the logo, I'll get some pictures and email them to you soon

[@domingosiglesias9186]

I couldn't attach the photo here. But it's the blue diode that's in the photo on the top right. It is in parallel with the black diode 1n4007.

[@dieselbenzrevive6820]

awesome

[@lawrencepellegrini2687]

I love your videos, I have a 95 R129 convertible, SL 320, has a Beckmann throttle body with actuator built in, amplifier is in (I'm guessing) the passenger side compartment under engine hood, near windshield. I've replaced ignition harness and several other wiring sections that were biodegradable. Runs great, just no cruise, I'm at wits end and need some diagnostic advice please, thank you.

[@trythistv]

Absolutely! It should be quite similar, does it just act completely dead or will it engage sometimes and then kick back out? I had a 95 E300D that also had the biodegradable wiring harness. talk about frustrating. Replacing the harness was the best route no doubt! I did find that the R129 and W124 cruise amps are supposedly interchangeable, and the w124 unit should be plentiful for troubleshooting or repair: www.benzworld.org/threads/cruise-control-function-fixed.1433986/ And that does confirm the amp is on the passenger side right near the hood hinge area.

[@lawrencepellegrini2687]

@@trythistv Thank you very much, I'll look into that, the cruise worked prior to ignition harness install, lately cruise doesn't connect at all. Is there a test to verify if my amp is faulty ? thanks again

[@davidjones7372]

Do you sevice cruise control module I've got one for my Harley Davidson that needs fixing??

[@davidjones7372]

There's no way I can do it

[@trythistv]

Very sorry but no, I'm a boat and jetski mechanic by trade, I just dabble with fixing my own stuff for fun and try to document my adventures for others to watch on here and hoping it helps someone out!

[@arielrighetti2818]

hi i ask you, are they the same capacitors for the 14 pin amp as for the 10 pin one ????

[@trythistv]

I'm not sure, I would suspect they are, but I haven't come across one yet to disassemble.

[@mikebentleyturbo1]

Hi Tom great info but your polarities are all mixed up on the pdf, could you clarify please? thanks

[@trythistv]

Oh? Which ones are you wanting clarification on, I think everything is accurate on there unless I missed something, I'd be happy to double check though!

[@mikebentleyturbo1]

@@trythistv in the first list you say solenoid pin 6 you say tap 12+ but then in the colour code list underneath pin6 green you say is solenoid negative (which I think is the correct one) and vice versa? Cheers Mike

[@trythistv]

Ah, yes I guess that could be confusing, Solenoids are not polarity specific, so applying ground and power in either direction will make it click, I will correct the document though, as I did indeed have it backwards. Pin 6 is intended to be ground, and pin 7 is intended to be power for solenoid. I'll have the new document on the site shortly! Thanks for noticing that!

[@mikebentleyturbo1]

@@trythistv Thank you for putting up the information! and videos :)

[@mikebentleyturbo1]

@@trythistv Hi again Tom, just to say many thanks for your help, replaced caps and reflowed all solder joints and now my Bentley has cruise control again :) . box was 412 212/4/1. Thanks again Mike

[@greenmile4233]

Hey, I have W126. would the amplifier on that be similar if not identical in its configuration?

[@trythistv]

It should be identical, or very very similar, sometime from the mid 70s up to the mid 90s used very similar amps and actuators across just about every Mercedes. I know the 95 W124 I had used a similar setup, it was slightly different as far as the connectors and pin assignments, but internally it was similar enough that the process of replacing the capacitors and resoldering the bad joints fixed it back years ago when I still had that car.

[@dewick134]

Hello. I was searching for anything that would help me know more about the cruise control on my 1983 Mercedes SL. I had it in a shop two years ago and they put a new cruise control in the car. When I tried to use it, as soon as I set it, my car took off like a rocket! I tried it over and over and it did the exact same thing. I told the shop owner and they replaced the cruise control with another unit. It did the same thing. Does this sound like the problem could be the amplifier? I would love to have my cruise control working. Thanks for any help or advice you can give.

[@trythistv]

It could be multiple bad amps, or possibly the wrong amp for your car? But That kind of problem really strikes me as an amplifier or wiring issue. The amp may not be able to see the throttle position from the actuator and will accelerate to full throttle. Grab the testing manual from the website (trythistv.com/cruise-control/) and pay closest attention to test 5 (pin 3 of the actuator to ground) under the actuator portion and then test 2 (resistance of various wires on the amp plug) under the wiring under the dash tests. Pin 9 to ground at the amp plug should be the same reading as pin 3 on the actuator plug under the hood to ground. Check those places for any erroneous readings, I suspect the trace for throttle position in your actuator has worn through. It is super common and the only repair I know of is to replace the actuator. But testing the wiring first will rule out any other potential causes. Could also be related to the amp seeing speed signal or such, but the cruise shouldn't engage if it wasn't seeing any speed signal, and should set at whatever signal it gets. I suspect some kind of feedback problem. I'm leaning towards the throttle position traces in the actuator, but it could be speed signal to the amp, or the wrong amp.

[@dewick134]

@@trythistv Thank you so much for your time. Of course, I don't understand a word you wrote, but I found another shop who specializes in Mercedes Benz cars. I am going to give them a call and see if they will look at the car for me. I will let him read your thoughts if he is willing and maybe he will know what you are writing about. Would it be possible for him to call you if and when the time comes if he is willing? From what I understand, the garage put a new cruise control unit in the car. Actually, they put two in because the first one didn't work correctly as I wrote. It shot off so fast it was very scary! The second one did the same thing. Anyway, thanks again and if you are willing to speak to the shop person if he/she can't find the problem it would be awesome.

[@trythistv]

Shoot me an email: tom AT trythistv DOT com, I can get you my contact info, maybe we can get him on the right track!

[@dewick134]

@@trythistv That would be awesome! Thank you. I am picking up my car this coming week and will be trying to take the car to another shop that is closer to my home. He advertises that he only works on Mercedes so I will see what he says. I will keep your email and get in touch if this guy is willing to work on it. Thanks again!

[@mrfajita]

Any chance you have the color codes or ratings of the large resistor located between the two pairs of heat-sinked transistors? It is fried on mine, so I can't see the color code to source a proper replacement

[@trythistv]

If I've got the same amp as you, there are 2 resistors, one larger and one smaller between the heat sinked transistors, the larger one has a brown green brown gold colors on it, which should be a 150 ohm 5% resistor, I double checked with a multimeter and I got 150.3 ohms across it. Hope that helps your repair!

[@mrfajita]

@@trythistv You're the man, thank you! Hopefully I can get mine working between that and the fixes in your video!

[@curtisjohnson1071]

Do you repair these if I send you mine, I have a 1992 Merc?

[@trythistv]

I do not at the moment, I repaired my own, but don't currently plan on offering any kind of rebuild service at this time.

[@MrTesedgar]

Hi very nice . Question mines only have 2 capacitors can I email u a picture thanks.

[@trythistv]

I bet you've got the same one as a few other viewers have asked me about. Absolutely send me a photo, tom at trythistv dot com and I'll reply back to you with the info on which ones are where that I really need to add to the documents on the website but have failed to get done in a timely fashion 😂

[@MrTesedgar]

Hi I send u a picture on the email u send me can u all tell me the size of capacitors need thanks a lot . Really appreciate

[@trythistv]

@@MrTesedgar I never replied to you! The only 2 visible in your photo are both 16v 47uF from the looks of things

[@rb.867]

Do you repair them for w126 owners ?

[@trythistv]

I haven't really pondered offering any form of repair service, I'm mainly focused on enabling other people to do the repairs, But I may offer repair services at some point if I could justify the time and set up a good way to test and all that.

[@vintage76vipergreenBeetle]

👍

[@Uc9uE3pKsS6uQ]

where to purchase capacitors ? thanks!

[@trythistv]

Pull yours apart to make sure you have the same style capacitors, there are some differences between amplifiers. I got mine from mouser, these are the part numbers: 22uF: 647-UVZ2A220MED1TD 10uF: 598-106TTA100M 2.2uF: 598-225TTA100M Possible alternative capacitors, I have not tried these, but they are the same on paper: 22uF capacitors: amzn.to/2xnz48c 10uF capacitors: amzn.to/2Si9pVu 2.2uF capacitors: amzn.to/3bQCDTk

[@Uc9uE3pKsS6uQ]

@@trythistv Thank you !! can I mail to you 5 actuators, so you can tell me if some of them work on not. I have no way to test it.

[@AsAs-fk6ss]

Hey, I have a problem with a 116 450 speed control.

[@AsAs-fk6ss]

Madder Board is different from 123 and 126.

[@trythistv]

I believe they use a vastly different actuator, more like the vacuum pod system my trucks have to pull the throttle open, of course my w116 experience was a '80 300sd so a 450 may be different, but I would suspect if it is the vacuum system checking for proper vacuum would be a good first step, and from there even though the cruise amplifier might be different I bet on the inside it is similar, and replacing the capacitors and reflowing the solder joints might solve it if the actuator and everything else is working

[@AsAs-fk6ss]

@@trythistv Thank you my friend for the great information I will make your advice step by step

[@stuffdoggg]

My vdo board looks very different , i only see 3 capacitors . 1984 300d

[@trythistv]

Did you check the pdf document on the website? ( trythistv.com/cruise-control/ ) If it doesn't look like either of the amps in that document could you send me some photos of it? Email them to tom at trythistv dot com If you could!

[@stuffdoggg]

@@trythistv yes it’s the other one you have pictured in the pdf . Thanks !

[@jaysonbrandt5780]

What type of capacitors know I need

[@jaysonbrandt5780]

Sorry what type of capacitors do I need

[@trythistv]

Howdy! I put them in the description but youtube is making it very difficult to find that description anymore, so here is what I used: Capacitors I used were ordered from Mouser, with the following part numbers: 22uF: 647-UVZ2A220MED1TD 10uF: 598-106TTA100M 2.2uF: 598-225TTA100M Possible alternative capacitors, I have not tried these, but they are the same on paper: 22uF capacitors: amzn.to/2xnz48c 10uF capacitors: amzn.to/2Si9pVu 2.2uF capacitors: amzn.to/3bQCDTk (Those are amazon referral links, if you buy those I get a small commission at no extra cost to you) I've got such a mountain of them I'm planning on starting to give away little baggies of them once a week until they're gone, I've got to figure out the logistics of that and get it going soon!

[@AE-TDK]

on my 1982 240D, I did every thing in video 1 all checked out ok, did everything in video 2 all ok, bought a new amplifier hooked it up and still no cruise control. please help.

[@trythistv]

I'm assuming it just acts totally dead if you hold up on accel set? If so check your brake lights, I had led tail lights and one brand made the cruise act up, another was just fine, also any bad connection there could cause the system to not function at all.

[@AE-TDK]

@@trythistv I do have LED lights yes

[@trythistv]

Just for a test swap them out for some regular bulbs, just the brake lights are important as far as I know, if the cruise works, you'll need some led bulbs with ballast resistors I believe it is called, or add resistors elsewhere, as the cruise uses the brake lights to ground, with my led bulbs I could see them light up faintly when I plugged in the cruise amp and the car was running

[@AE-TDK]

@@trythistv will replace, i still have the regular 💡 will report back tomorrow. Thanks for your help.

[@trythistv]

Sounds good!

[@unaeruditi]

Tha

[@philen]

Thank you!