Rotary Alkymist

Hi everyone. I've spent countless hours on this site over the years and I'd like to thank all of you all for the countless bits of priceless info that you've shared here.

Just for the record I have an '88 s4 n/a chassis/s5 turbo jspec/ n374 ecu/n370 afm/n370boost/s5 n/a EM harness/s5 turbo trans/ s4 everything else. Don't ask how I got this to run but it does.

I just got my rebuild running this week! She was asleep for 13 years! I feel like I"m 20 again!

So, here's the problem. I have no blower, no air/mix control, rec/fresh, nothing. I've conducted all tests in FSM and everything was pointing to the fan amp. So I opened it up and there were 2 transistors that failed the test. They are identical with the number 1001 7k.

Here is my question, does anyone have a cross reference for this transistor? I have scoured the net , which took about 5 minutes because there is simply no documentation availabe, at least in english haha.

I actually have a spare unit but it's a 1000 k away -part of me would get a rush of gratification if I managed to fix this POS for less than 5 bucks haha.

And what is up with the 17-pin connector? Shame on you Mazda ... shame on you.

Thanks everyone!

Rotary Alkymist

i did stumble upon this.

https://www.rx7club.com/2nd-generati...c-dip-1105069/

I'll follow up soon.

TonyD89

iTrader: (10)

Found this just putting 1001 2k into the Google search bar.

smd TRANSISTOR code marking 7k datasheet & application note - Datasheet Archive

http://www.lcdtvrepair.us/transistor...cordset1=61355

There were other options. Maybe satch will chime in with some help. There's also a member on here named Pele that rebuilt a lot of the electrical components in these cars. I don't know if he ever messed with the logicon but you could try him.

Rotary Alkymist

Thanks for the info Tony. I searched the data sheet for FJN3305R here:

FJN3305R datasheet(1/4 Pages) FAIRCHILD | NPN Epitaxial Silicon Transistor

This is indeed the right component. It has a built in bias resistor which was giving me strange readings. So these little buggers were deemed functional in light of this new info. You will measure 10k +/- if you measure ohms between base and emitter. Someone correct me if I'm wrong but this strange guy also has a diode between collector and emitter which will obviously not read open. Damn electrons.

I moved on to diodes and I may have found some questionable ones but more testing is needed. These parts should be easier to find. I'll keep yas posted.

I'll also note that I've checked all motors and linkages and everything runs great.

Logicon passed all tests but failed all corresponding motor circuit modes. I did manage to get two lights working again, at the expense of frying two leds. Sweet. Light circuit does need work but is functional(mostly -most likely due to bad solder points).

Gen2n3

iTrader: (1)

I'm curious to see how your repair goes after replacing the transistor. Good work on finding a suitable replacement. Perhaps the Logicon Amp component post (https://www.rx7club.com/2nd-generati...c-dip-1105069/) could be updated with your findings?

As for your diode testing, be aware that there is a difference in testing a Zener diode and a standard diode. Here is one link as an example: How to Test a Zener Diode

Best of luck with your repairs!
Cheers,
George

Rotary Alkymist

Hi George.
That's the thing, after finding the datasheet the transistor tested good so I kept on searching for clues. Diodes tested good. I looked at the biggest board closely and found many cracked solders. Some of them included paths to the ICs and the ICs themselves. The IC part no. is toshiba ta 8050.
Datasheet can be found here:

http://www.sullivan-county.com/ele/pdf/ta8050p.pdf

This datasheet was the breakthrough. It helped me find the solders that needed fixing. With the info in that datasheet you get a good idea of where things are coming from and where they're going.

I also found some great info here:

http://www.andysautosport.com/images...con_repair.pdf

Aside from the IC solder points all my bad solders were where the ribbons are connected to the board as was explained in the link above -very informative link for someone who's not too seasoned in electronics.

After soldering about 50 damn points I retested and to my amazement it was working. It came down to bad solder points. It usually is! I was working with really bad lighting for the first couple of nights. I could've spotted them sooner but I feel that the fact that it went overlooked led to some great information about the logicon.

My unit was tampered with before I had it in my possession. It was cracked and my dash was also tampered with. I was a bit scared to touch the dash, I mean it being so old, I felt something was bound to break -leaving me with vibrations that I would have to live with forever lol. I ended up cutting the 17 pin connector at the logicon(14 wires in total) and I added my own connector with molex hardware. I did stumble upon info on this site about the location and access of this connector but I was getting a bit impatient with the whole thing. I looked at the cutters and made a choice haha.

All in all I can't really say what fixed the problem. Definitely solder, but which points? Beats me really. I know, it's the worst conclusion haha.

Gen2n3

iTrader: (1)

Alkymist,

How did you repair the solder joints? Did you de-solder the eyelets then flowed new solder into the eyelets? If you suspect bad/cold solder joints then it is important NOT to reuse the solder in those joints. The re-flowed joint could be weakened or form a cold joint again. Think of it as re-welding over a bad weld joint on a steel beam.

Gen2n3

iTrader: (1)

In case you haven't seen this post, check out your logicon faceplate for bad solder joints. This is what I found on mine: https://www.rx7club.com/2nd-generati...older-1105040/

Cheers,
George

04Green

A quick note from work...

I am about 90% through fixing mine. The primary culprit, every single current limiting resistor was bad. The used one I had also had several of these resistors fried. They were in the K ohm or M ohm range. This will allow the box to past the bench testing unless you put a load across the output.

I do not have my notes, but trace the motor signal back on the board. There will be a resistor between that line and a transistor base. That should be in sub-10 ohm range. I suck at reading the codes, but they should be under 10. I have seen different codes for different transistors (all same part number). The transistor is rated to 3 amps.

In addition to the current limiting resistors, I found 1 bad zeiner diode.

When I get done, I plan on writing up the circuits and making a short guide.

It would really help if you could share pictures of your current limiting resistors, close enough that the color codes could be read. I think all of mine were different.

Rotary Alkymist

I used a plunger on all points. Fun stuff. I actually had to solder in some jumpers at some places where I pulled the transistor out in a bad way haha. I reinstalled it and everything works as it should. It was vindicating to here the motors doing their thing. I feel pretty lucky that nothing was fried. My leds for mix control settings are still out. The leds themselves are bad. I'm wondering it someone touched this before me because it the module(locicon) was cracked at two of the screws.
It seems that there are many scenarios one can find himself in with this. Every case is probably unique to itself.

I will mention too that the logicon power wire runs from FI-50 connector. It's a big blue connector, one of two blue connectors left of steering column. It is the connector furthest from steering column. Color on 88 n/a is LgB(light green black). Not sure about turbo.

I feel for you 04Green. Sounds like a nightmare. I think these bad boys are hovering around 85-100. It was my next step. One more day of me cursing about it and the wife would've made buy one lol. She was getting sick of having a battery on the kitchen table lol(it's getting cold up here!)

Rotary Alkymist

I'll also mention that my car was sitting for 13 years indoors. I'm guessing that this unit went bad over time and because it was never powered up it didn't get a chance to fry.

04Green

So far, I think it was a diode and the resistors. And, I read the stripes wrong on 2 and got the wrong parts. That $1.89 will haunt me for 12 minutes.. Silver vs Grey, FML.

The used one I bought donated a few, but the ones for the air mix door were both bad on that one as well. The used one was supposed to be good, had a bad LED, did not run the air door at all, but did run the re-circ door. Again, that one was resistors.

If it were not so danged hard to get in and out, I would work on fixing the other one.

Gen2n3

iTrader: (1)

Alkymist,

Did you ever fix the problem with your logicon?

Cheers,
George

04Green

George,

In the end, it is sorted. Well almost sorted..... All of the issues, I believe, were failed resistors and diodes. The zeiners were a bit harder to test but I could figure out which ones were bad. I tested everything and it works. The ECU was not able to power the compressor relay, so I added a helper relay and that works fine as well.

I had to set the car aside to work on my son's car for a bit. I drove it for the first time, at night, a week ago. One of the display is bulbs is out. So, it has to come out one more time.

Mike