by "Urambo Tauro" (urambotauro)
Published 08/07/2017 at 08:45
by "Urambo Tauro" (urambotauro)
Published 08/07/2017 at 08:45
Tags: electronics
; circuitry
; pixie wrangling
; wrenching
STARS: 0
I found a bad resistor! And that’s not all...
Fist of all, thanks everyone for the responses yesterday. I’m familiar with some electrical stuff, but a noob when it comes to fine electronics. I really appreciate your input.
!!! UNKNOWN CONTENT TYPE !!!
Since this CCRM doesn’t have a traditional coil-type relay for the AC circuit, I started poking the other components on the board with my multimeter. One of the first resistors I tested (R9) came up bad, giving me a fussy reading of somewhere around half of its stated resistance.
But before getting too excited, I continued testing, and soon found another bad resistor (R11). And a bad diode (D4).
Since I was doing a round of individual component tests, I went ahead and started trying the relays one more time, just for kicks. Surprisingly, *pop* one let the smoke out! I have no idea why. All four of them were good just the other day . Alas, the low-speed fan relay now has zero resistance across its coil. Well, that sucks. I wonder if one of my test probes slipped earlier. Maybe I errantly discharged a capacitor or something.
I can see now why remanufactured modules are so expensive. Between the diagnosis, labor, and testing involved, a hundred bucks doesn’t sound so bad after all. But I like learning, and am not quite ready to give up on this board yet.
Speaking of learning, I hear that capacitors can’t be tested in-circuit. And I’m still unclear as to how to perform a complete test of a transistor, but a preliminary diode check between Base and Emitter terminals is showing 3 of them (Q4, Q5, Q6) to be bad.
The mosfet on the side, which appears to be an important part of the AC “solid state” relay circuit, also failed a diode check between the B and E terminals.
So it looks like this board will need two 100k resistors, one relay, one diode, three transistors, a mosfet, and maybe (?) some capacitors. Is it worth it? Should I just trade it in (core) and get a remanufactured unit?
BTW, I’m having a hard time getting good close-up pics, but I stumbled across
this TCCoA thread
, which contains excellent photos of a board identical to mine. Check it out for a better view of what I’m looking at.
"CTSenVy" (CTSenVy)
08/06/2017 at 21:06, STARS: 1
I think I would pay for a new mod at this point, something blew in the circuit and is probably taking out other parts of the circuit.
"Nibbles" (nibbles)
08/06/2017 at 22:21, STARS: 1
Fuck it, LEARN. Those components are cheap and, if you get it working, good on ya! If not, fuckit and get a reman. You only stand to lose the knowledge.
"XJDano" (xjdano)
08/06/2017 at 22:27, STARS: 0
I know nothing of circuit boards but depending on what kind of close ups you want, I bought this cheap clip on lens kit that goes over your phone. It set I got was a wide angle fisheye lens and a macro 2 part that can get super close ups, but you almost have to be touching it. See below
"XJDano" (xjdano)
08/06/2017 at 22:35, STARS: 1
This is not the one I bought but same idea
Well the car should be at the bottom, but you can get idea.
"Urambo Tauro" (urambotauro)
08/06/2017 at 22:58, STARS: 0
I like the way you think.
Any recommendations on where to order parts from? Radio Shack and Digi-Key are the only popular suppliers I know about, and both of them are bewildering me with their search results.
I feel like maybe I’m using the wrong search terms, trying to go off of the numbers printed on the components. I tried reading a couple of data sheets, but they’re throwing way more information at me than I know what to do with. I guess I need to know more about what I have before trying to find matches.
At least resistors are easy to decode haha.
"Urambo Tauro" (urambotauro)
08/06/2017 at 23:01, STARS: 0
Yeah, some of the first pics I took came out good. I was holding a magnifying glass against my camera lens, and that seemed to work sometimes. Those lenses aren’t too bad in price, though...
"Urambo Tauro" (urambotauro)
08/06/2017 at 23:06, STARS: 0
If I was in a hurry, I think I would go ahead and just buy a module. FWIW, I’ve learned quite a bit so far.
But since I have a second vehicle, I think I can afford to throw a few bucks at trying to repair it first. However, one thing kind of bothers me: the traces on the back of the circuit board have a wavy/wrinkled appearance that reminds me of peeling paint. Is that normal, or a sign of deterioration? It’s all underneath a layer of silicone conformal coating. Mine looks just like this pic from TCCoA:
"Nibbles" (nibbles)
08/06/2017 at 23:19, STARS: 0
Man I ain’t done this work since the 90s when we ordered components out of massive fukkin’ catalogs. Try not ordering off of part no, but off of values. You may have better luck
"CTSenVy" (CTSenVy)
08/06/2017 at 23:58, STARS: 1
That looks weird, like something is getting behind the traces.
If you are willing to play around, you may want to remove those transistors and the mosfet and test them again, you maybe getting weird feedback with them still being in circuit.
"diplodicus" (diplodicus)
08/07/2017 at 08:23, STARS: 0
You have any part numbers from what you pulled off?
"TorqueToYield" (torquetoyield)
08/07/2017 at 09:14, STARS: 1
I like Mouser a hell of a lot better than Digi Key, their website is sooo much better.
SparkFun is more hobbyist oriented but without the huge selection of the bigger distributors.
Future Electronics is another slightly less well known distributor I’ve had good luck with.
Like others have said it’s best to go by ratings, specs, and case size instead of exact part number match.
"Urambo Tauro" (urambotauro)
08/07/2017 at 10:32, STARS: 0
I haven’t de-soldered anything yet. But some of the parts have multiple numbers, and I’m not sure what’s a spec, and what’s a part number.
The mosfet reads “5102FBBC”, “H4”, “48”, what looks like a stylized H , followed by “CL”, and finally “C”.
The transistors all have what looks like a stylized N , followed by “448”, with “1101” below, then “CG”.
The numbers on the diodes go all the way around, so I’m not sure where they begin and end. Looks like they say “4201AA” and “GI9444” below that.
"diplodicus" (diplodicus)
08/07/2017 at 11:37, STARS: 1
1N4007/1N4007RLG (RLG is lead free for Rohs compliance.) works for the 4201AA diode. You could find a 400v like the original but the 1000v is only .18 doubt the 400v is much cheaper.
Couldn’t find any data on the others.
"Urambo Tauro" (urambotauro)
08/07/2017 at 11:51, STARS: 0
Thanks for finding that match; how do you do that? Is “4201AA” a code that summarizes its specs? Or is there maybe a part number cross-reference chart somewhere?
"diplodicus" (diplodicus)
08/07/2017 at 12:32, STARS: 1
Found this link https://wellgainelectronics.com/more-diodes-rectifiers/38712-gi-ford-4201aa.html
Then I just searched my system at work for 1a diodes. Diode/transistor and some other semiconductors have basically meaningless pn as far as I can tell. Fuses,relays,capacitors tend to have p/n codes in datasheets.
I think it’s because there’s more variety. Like you can order multiple different cases for the same voltage/mf ratings for a cap. Then with relays you have different contact configurations, coil voltages.
"Urambo Tauro" (urambotauro)
08/07/2017 at 13:15, STARS: 0
Yeah, that link came up in my googling too, but only when I searched for “4201AA”. Searching for “GI9444” doesn’t seem to get me anywhere. I was assuming that one of these was a spec code, and the other a part number. Not knowing which is which, I hoped that maybe if I could find both numbers on the same page, then I’d be certain that I was looking at the right part and have a list of specs. That’s about as good as my Google-fu gets haha.
So that’s a 1a, 400v diode, then... and it’s okay to go higher in voltage rating, right?
"diplodicus" (diplodicus)
08/07/2017 at 13:42, STARS: 0
Ya with a diode you can go with a higher amp/voltage rating. The silver band on the diode denotes the negative end, so just make sure you know how the one you’re removing is oriented.
For the capacitors you can go with a higher voltage, but not a higher microfarad value. Sometimes caps have really odd voltage values that are tough to find in stock.
You have any close ups of the MOSFET could narrow it down to a certain case style probably. Same with the transistors.
"tpw_rules" (tpwrules)
08/07/2017 at 14:14, STARS: 1
Old circuit boards look like this, it’s the tinning done behind the soldermask. They’re probably using an old manufacturing process or something.
"Urambo Tauro" (urambotauro)
08/07/2017 at 14:21, STARS: 0
This is about the best I can do, even with a magnifying glass. I’m gonna have to get a lens like XJDano linked to.
The top line reads “5102FBBC”, then below that “H4” on the left and “48” on the right, then the next line down has kind of a black H shape surrounded by silver print, followed immediately by “CL”, and finally “C” to the right of that.
Curiously, the mosfet pic from that TCCoA thread has some different markings:
“5102FBBC” is still the same, but some of the other markings don’t quite match up. I wonder if they’re just manufacturing date markers or something, because the board itself has the same Ford number as mine, so they must be functionally identical.
Oh, and as for the little transistors, mine look just like the TCCoA pic, except that they read “448” at the top, instead of “530”.
"diplodicus" (diplodicus)
08/07/2017 at 14:58, STARS: 0
The big one looks like its probably a TO-220 Case, but that won’t help much since that’s extremely common. Normally with obsolete transistors/semiconductors you can find someone in hong kong selling them on ebay, but no dice with that one. Maybe someone on the forums has a cross?