Electronic Component Identification Rebuilding Climate Control Amp - PeachParts Mercedes-Benz Forum

Assault · #1 11-08-2014, 05:16 PM

Hello,

Working on sorting out the climate control, and found out that my amplifier is in need of a rebuild. Yes I could go buy a used one for X dollars, however, I am set on rebuilding this one. This car was designed to be rebuilt and repaired unlike most modern junk now a days.

I have been able to locate most of the ceramic resistors at digikey
1x: RES 12K OHM 1/2W 5% CARBON FILM
1x: RES 510 OHM 1/2W 5% CARBON FILM
1x: RES 750 OHM 1/2W 5% CARBON FILM
1x: RES 180K OHM 1/2W 5% CARBON FILM
1x: RES 10K OHM 1/4W 5% CARBON FILM
1x: RES 47 OHM 1/2W 5% CARBON FILM
1x: RES 5.6K OHM 1/2W 5% CARBON FILM
1x: RES 3.9K OHM 1/2W 5% CARBON FILM
1x: RES 180K OHM 1/4W 5% CARBON FILM
1x: RES 5.6K OHM 1/2W 5% CF MINI
3x: RES 1K OHM 1/2W 5% CARBON FILM
Total $1.71
1x: 118k ohms 1% 1/8W (found on ebay 3.79)

I am having trouble identifying the remaining parts

The Voltage regulator 2x
Diodes 6x (Small IN4005 p?C, ?= looks like an 8 that is curved with the c i.e p8c Large ZY 18 GP
Transistors x2 markings (13c 237c J.4, the other one melted)
voltage regulators (NL651 D44 H11 (Motorola brand)
as well as 2 other components that I am unable to identify
one is made of ceramic (i think) and I am able to scrap it off with my finger nail. (light gray)

Assault · #2 11-13-2014, 08:13 PM

Would anyone be willing to shed some knowledge on this subject? ...Por favor

ah-kay · #3 11-13-2014, 09:48 PM

With no dis-respect to what you are doing and your good intention but I think you are wasting your time, IMHO. For a start, the circuit was designed 20+ years ago and any solid state components would be obsolete and difficult to source. There is no schematic so it is difficult to find out the part number. The price will not be cheap even if you can source them. When all is said and done, you end up with a circuit board with unknown quality as there is little way to test. The problem may be elsewhere as I have never seen a circuit board so badly burnt. It is possible the newly 'repaired' board would suffer the same fate when plugged in.

I would suggest to swallow your pride and get one from the junk yard and be done with it. But it is your time and money. Good luck.

OM617YOTA · #4 11-13-2014, 11:00 PM

First of all, I mostly agree with ah-kay. Doable? Yes. Less hassle than just going and buying a good one? No way.

Many parts are surprisingly available. If you get stuck locating a particular part, shoot me a PM. I'm a sales rep for an electronic component distributor, and while we're a franchise distributor, my company has retained access to the independent market specifically so that we have 20+ year old parts available to us. Be aware that due to PO mins with other companies, you may be looking at $50+ for a single component.

Your gray cylinders look like wire wound resistors, as do the darker gray/black cylinders. The red box(which I notice does not have a pen mark on it) is a metal poly box cap. Which parts exactly were you needing to ID?

Not very common to see mixed SMT and through hole devices on the same project.

TnBob · #5 11-14-2014, 01:18 AM

Id shoot James Dean a message and ask him. He is the resident CCU expert.

jay_bob · #6 11-14-2014, 08:19 AM

The SMT daughter board is very interesting, looks to be something that was a replacement for an 8-pin DIP IC. I'm curious what the original IC was, I suspect since this board handles the PID function for the monovalve it was some sort of op-amp.

I agree with ah-kay, something is shorted in the system to cause that much discoloration on the board. Looks like the transistor (the one with the flat facing the resistor) is cooked as well, I see damage to the case. There is a smoke stain on the adjacent red capacitor.

I would check those 2 Motorola FETs up there in the corner, they probably switch the current to the monovalve and if you have that much heat damage in the board the FETs may well be fried.

If the back of the board is not damaged (i.e. traces not delaminated from the substrate) then it probably can be saved. The parts appear to be COTS (Commercial Off The Shelf) except for that SMT daughter board.

funola · #7 11-14-2014, 10:53 AM

Quote:

Originally Posted by jay_bob

The SMT daughter board is very interesting, looks to be something that was a replacement for an 8-pin DIP IC. I'm curious what the original IC was, I suspect since this board handles the PID function for the monovalve it was some sort of op-amp.

I agree with ah-kay, something is shorted in the system to cause that much discoloration on the board. Looks like the transistor (the one with the flat facing the resistor) is cooked as well, I see damage to the case. There is a smoke stain on the adjacent red capacitor.

I would check those 2 Motorola FETs up there in the corner, they probably switch the current to the monovalve and if you have that much heat damage in the board the FETs may well be fried.

If the back of the board is not damaged (i.e. traces not delaminated from the substrate) then it probably can be saved. The parts appear to be COTS (Commercial Off The Shelf) except for that SMT daughter board.

How do you know those are FET's? Have you worked on that board before? W116 was designed in the 70's. The modern FET was still in the labs in the early 60's and I doubt those are FET's.

ah-kay · #8 11-14-2014, 11:04 AM

Quote:

Originally Posted by funola

How do you know those are FET's? Have you worked on that board before? W116 was designed in the 70's. The modern FET was still in the labs in the early 60's and I doubt those are FET's.

Does it matter what they were??? Have a beer and chill down.

My comment in previous post still hold true.

funola · #9 11-14-2014, 11:12 AM

To the OP, are you trying to replace every component on the board to rebuild it? That is way overkill and not called for. Any resistors not burned are very likely still good so don't replace them. The wire wound resistors if not open circuited are probably still good. You can check all resistors with an ohmmeter. You can also check transistors and diodes with an ohmmeter for opens or shorts- if neither, they are probably still good. I'd check all the diodes and transistors with an ohm meter and replace any that are bad. Replace the burned small transistor and see if that does it. The SMT DIP will be a show stopper if bad since it may be difficult to find. Before powering it up, check the harness connector for shorts and fix first or you may blow it up again.

As for the burned transistor, you need to identify if it is a PNP or NPN and replace it with the same type (I doubt those are FET's also). You do not need to replace it with the exact part #. You can get generic replacements from Radio Shack or find one from old appliances like radios, printers, TV, telephones and steal a transistor of the same shape (and type PNP/NPN) and it will more than likely be good enough.

Edit: I'd suggest replacing the 2 caps (the red one and the round electrolytic at the corner. Caps go out of tolerance or go bad with age.

funola · #10 11-14-2014, 11:13 AM

Quote:

Originally Posted by ah-kay

Does it matter what they were??? Have a beer and chill down.

My comment in previous post still hold true.

Off course it matters. I am chill. The OP wants to do this, Let him have his fun.

Edit: That board does not look that bad actually. The brown burnt spots on the board is from prolonged heat from the wire wound resistors being fed too much current. I have fixed many things electronic without a schematic or documentation. This one should be easy if the SMT is still good.

Not FET
http://www.st.com/web/en/resource/technical/document/datasheet/CD00000942.pdf

LNGfish · #11 11-14-2014, 05:23 PM

My CCU got roasted/toasted " I think " from a failing Ignition Switch. I replaced the Ignition switch 1st and then a member here sold me a perfectly good used CCU and all great now! Good luck with repairing it if you go that route, I don't have the patience. I would however check voltage drop across your ignition switch if it is original. There should be zero if any is my guess, guessing 0.1 volt max. I heard these CCU's get burned from a bad water circ. pump for the hot water heater too. I think you need to install a 1 amp fuse in that line on the firewall. I did that but one day dropped the fuse, so I just left the fuse out as I don't think I need the circ. pump anyway where I live.

cooljjay · #12 11-14-2014, 06:41 PM

Ok, so to cause this damage....the auxiliary water pump more then likely froze causing the burnt amp. MB never though of fusing the pump...

Don't waste your time rebuilding it....with out a schematic to work from, you are shooting in the dark. You need to know the specs of the components, you needed to know what they read, you need to know how and what they were designed for..

As was said to sorta of know what is bad, the only way is to desolder and measure all components. Somethings like the chips, cannot be tested...well with out multi thousands of dollar equipment. You also need more advance testers to test the transistors...as well as an oscilloscope to see the signals..

I repair and restore vintage audio items, so when something like this goes bad....I think of how I can repair it...but like this...its better to buy a rebuilt/new one..

Member JamesDean does the cruise control....he has a jig made up for testing the components...that is why we all recommend him...hes already setup with all the goodies...

Assault · #13 11-14-2014, 07:08 PM

Thank you everyone for the replies.

The wires the connect into the amp check out there is minimal resistance .01 at the most.

However with the amplifier when grounded and testing the resistance pin 7 shows 19.5 and pins 2 show 4.9 and 3 shows 3.9 and pin 8 shows 1.3. Needless to say I think it is perfectly 'fried'. Thank you to the posters, I thought this could be a simple 'replace old components' and it would be good as new. Unfortunately, this turned out not to be the case.

Ill go ahead and say it, I think it would be best to bite the bullet on this one.