have a vacant building with 2 tac 50 cars. the air-conditioning died, mroom was very hot. both cars are down, the cpu green led would come on and stay on steady, then go out, and repeat the cycle, stays on for a minute or 2, and then out for a while, cannot communicate to either car. any ideas, were looking to get the ac fixed, and shut the cars down until they do. just checking to see if anyone knows why the led just stays on, and does not blink like on a working car. I'm hoping the cool air will bring them back to life, but just in case I'm looking for some ideas.

I've never seen that nor do I have that symptom in my notes. Does the DSP green light flash normally?

I would say the AC failure would cause this and most likely will be ok when its fixed. I have had full electronic lifts go nuts when the air con didn't work, but righted itself when fixed.

well ac fixed, turn cars back on, one car woke up, cpu led flashing normally, other car dead, cpu led on for a little while, then out. dsp led is flashing normally, so i would not suspect a power supply problem, now i can communicate to running car, but other car no comm ordering a new cpu. did a little research, looks like i can just replace the eeproms, and hopefully if U22 has not been damaged, then it should just run. has anyone replaced a cpu before?

I have on the TAC 32, procedure is the same I believe. Dump the blahblahblah.cfg file and the version of software file into the update folder, plug the USB stick in, hold rst and udl, release rst only, watch for the red flashing light to flash three fast, and release the udl. Fairly painless procedure now.

I tried replacing a TIV CPU once to rule out a problem and just swapped all the chips over and matched the jumpers, it didn't boot up. Is there an official write up on swapping the CPU on a TIV and/or TAC 50? I'm sure I'll have to do it out of necessity one day.

Changing CPU board can vary between
T4 older "DSP" Tac 50 and
Tac 50-03/04

If it's a older T4 Tac 50 DSP hold onto to your britches ... New style of SMT CPU board , have to upgrade the whole job

Contact Luke at "Access Electronics 301-645-1733. They repair the older CPU Boards. Does an excellent job.

It's a 1998 TIV, I'm guessing it's an older one?

thanks for the info, its an older tac50 with 6300JC3 CPU board. vertical express had them for 1395. We are waiting on customer, they may want to just repair, or buy new and repair other for a spare. Will give Luke a call, thanks Rolly. E-Man, there was only a paragraph write up for cpu replacement, it just said swap the appropriate chips onto the new board and insert. seemed to easy, so i was just checking to see if anyone had any experience. I did read in the manual that if you had to upgrade to next version of cpu board, you would need new software, if the car was in a group, all cars must have same version of software, so i can see Postal remark of how that could get interesting.

👍👍👍👍

Always forget the older TIV was considered a TAC 50. The older gear can be a royal pain. My new stuff is pretty cake.

update, i got my hands on a different cpu, installed it, and same problem. So i did the self confidence test, and the dsp, and pmi boards were no go, traced problem down to bad pmi3 board, unplugged it from rack, re did self confidence test, and everything passed except the pmi3 board of course, so i thought i was good to go. only problem, is the cpu led continues to slowly blink, 5 seconds on, 5 seconds off the good car blinks at one second intervals. even though self-confidence test passed, cannot communicate with the cpu with IMS, other car is fine. So i unplug everything except cpu, and same thing, no communication via IMS. seems like i should be able to communicate with cpu, without any pmi boards installed. both cpu do the same thing, could i possibly have 2 bad cpu? i don't think the software is bad, as the confidence test was good, said parameters were all go, i think it showed the version not sure now, ran out of things to do, so i replaced the 5 volt power supply, even though it was good, same thing. now I'm wondering, if it will run if i just replace the PMI3, although i doubt it, but one is on the way. any ideas? kind of strange, this is my first go at the tac50, thanks

I just had the same thing the other day and F2 was blown on the DSP. When I got to the MR, I had no safety circuit module wise (the hardwire string was good to ICS) and the red led on the DSP was on but after a reset it flashed a happy green but the CPU was still flashing slow. I also couldn't communicate with the car. Did you check those fuses on the DSP?

i did not, but i sure will thanks