KE83ZBM - tape deck doesn't load. Bad motor?

[nando]

So this has probably been the slowest rebuild ever - but about a year ago, I got an original stereo and rebuilt it, including new lights, belts, etc. Everything works great. there's no mechanical issues and all the caps look good.

But it won't load tapes. I have checked and re-checked the physical mechanism and it is fine. I can physically move the motor by hand and it will load the tape perfectly. Everything is smooth and as expected (I also have a copy of the repair manual, and have checked against that too).

There's a switch that engages when you push in a tape, that is supposed to turn on the capstan motor. I have verified the switches are working correctly when the tape is inserted. The tape deck itself does recognize the switch because it changes from radio mode to tape mode when a tape is inserted - this also verifies to me that the tape mechanism has power.

Anyone have experience with these that has any ideas of what to test next? I was looking a little in the manual and I really hope it's not the motor. Replacing it is physically not hard, but re-calibrating it correctly could be very difficult without the right equipment.

[nando]

Since there is basically nothing I can find on these (other than the factory manual, which luckily is easy to find, and input from bradnic) - I'm just going to document what I find and hopefully solve my issues, and maybe help others in the future who may want to restore their original Pioneer decks. Much of this also applies to the KE81ZBM, which uses the same tape mechanism.

Suspecting the capastan motor, I cobbled together a bench test harness to make diagnosis easy (plus I almost killed my battery, again, when I left the map lights on trying to test it in the car, lol). I have a bunch of extra JimStims (JS) from my Megasquirt days, which was the laziest way I could think of to come up with a switchable 12v power supply, plus it has screw terminals for grounds and every input and output you can imagine.

Otherwise I used some splice terminals for power and ground, a 12v laptop power supply from an ancient Thinkpad, some random terminals in my parts stash, and the backlight harness (which just unplugs from the main stereo harness). There's a million ways you could do the same thing - you basically just need 2 power leads and 2 grounds, one each for the deck itself and backlight.

The main power to the unit is supplied through the ignition switch (and the connector on the radio is labeled IGN, duh). But of course, when you switch off ignition, the radio would lose all memory (since it has no flash or non-volatile storage). Due to how the backlight is wired through the car's harness, that actually keeps a basic level of power enough to keep the stereo from losing it's memory (and security coding) because it comes directly from the battery.

At first I didn't realize you needed both the backlight power and ignition to turn on the stereo and only hooked up IGN. I was kind of afraid I'd fried it somehow, but I plugged it back into the car and it was fine (except the tape deck still didn't work).

After a little trial and error, I powered the backlight directly to the JS 12v power block, and the main stereo power input to the JS ignition output (which is triggered by a switch). Now it works just like it does in a real car. The anti-theft LED even flashes when it's powered off, and the alarm goes off if I jiggle the unit on my workbench (no idea how that works!).

Next I needed a way to directly test the capstan motor. These things seem really advanced for 1991 - I've taken apart a lot of electronics - everything is so compact you just can't stuff a multimeter in there to test things. The easiest way was to solder some ribbon cable to the 3 terminals that go to the capstan, so I could easily reach it with my probes (ooooh!).

That done, I powered up the stereo on the bench, entered my super secret security code (at this point, if I ever get this thing to work - I would actually be protective of it, haha). Then I pushed in my test tape - 1988's top 40 hit single from the band Europe - Superstitions (it only cost me 20 cents!). And as expected, the tape drive does.. nothing.

The deck display shows that it has entered tape mode, but the mechanism doesn't fully pull in the tape, and I'm left unable to hear the glorious 80's music I have paid so dearly for. Anyway, the point was to see if the capstan motor itself gets any power or if it is working correctly. Using the test leads and what I can assume from the manual and what I know about small electric motors I made some guesses.

I assume the middle wire is ground, since it's always low. On pushing the tape in, the first wire goes high (about 8v). The third wire varies a bit, but not enough to make much difference. I assume that is eject - but I can't test that since I can't get a tape to insert in the first place. Based on this crude and primitive test, I think the main electronics are fine.

That leaves the capstan motor, which based on everything else is likely toast. New replacements are basically impossible to find - Pioneer does list various replacement part numbers on their website (again, thank god they published the manuals back in the day - if you don't support right to repair, you should!). So that leaves me with scouring the interwebs for a used replacement.

I'll update this thread later with pictures if I find the time. Meanwhile, I'm scouring ebay for decks that look like they may have a tape mechanism that still works...

[nando]

Long story short.. the capstan motor was toast.

I bought another deck for parts, which ironically was cheaper than the first one - and also in way better shape (minus the code I don't have yet). I swapped the tape mechanism over (after replacing the belts, which are 100% going to be melted by now on any deck that is 30 years old), and it worked immediately. So hopefully soon, I can rock out to some tapes that could have been played in 1991, lol.

The nice thing was the 2nd parts deck came with a couple pigtails that I used to repair my original harness back to 100% stock. I did a lot of stupid shit when I was in my 20s, but one thing I did know was someday, somebody might want to make this thing stock again... so I basically didn't cut any wires on the original stereo harness, except the power wires, and severing the connector to the amp in the trunk (but leaving everything in place). Little did I know, 20 years later that future somebody was going to be me, lol.

Next I need to re-connect the original housing for the amp, and then make an adapter the Kicker 47KEY200.4 - somebody on this forum recommended it, and it looks to perfectly suit what I'm looking to get out of the basically stock system.

As an aside, I've been digging a little into the CD changer input. It should be possible to make an adapter to add Bluetooth - somewhat simply. it's a standard serial input, but of course, you have to figure out how to trigger the CD input. fortunately, the wiring diagrams for both the deck itself and the CD changer are widely available. We'll see how far I can get.