Thursday, August 11, 2022

Pioneer CT-F950 Reel Motor Rebuild

 As I mentioned yesterday, the first electrical issue I ran across in rebuilding this deck is that it kept dropping out of Play. A bit of sleuthing around revealed that the Reel Motor was the most likely culprit, so in I went.

These pictures aren't mine. I borrowed them from the HiFi Haven website, where member Pustelniakr was kind enough to document the entire procedure.

It's a small DC motor, with a couple of centrifugal switches on it to control the speed. In "Play", it runs at a reduced voltage, regulated speed, and in "Fast Forward" and "Rewind" it gets full voltage and really spins.

And it's a "can motor" inside another can!

The coiled strip of metal on the right is a strip of Mu-Metal for magnetic shielding. Even though the permanent magnet inside the motor can on the right is pretty well shielded, Pioneer used to the "belt and suspenders" approach to really keep the magnetic flux bottled up inside the cans so it couldn't degauss the tape as it was in the deck.

The two round grey things are silicone rubber shock mounts that suspend the motor can inside the shield can. It mechanically isolates the motor from the chassis, so vibrations from one don't upset the other.

The armature assembly out of the case after prying open some crimps:

The small toroid inductor is in series with the DC Voltgae coming in. There's a capacitor to ground on the other brush, and they form a filter to keep the electrical noise from the brushes on the commutator from getting into the other electronics.


My brush plate wasn't this dirty, but I cleaned it very well anyway. The brushes themselves appear to be a carbon/copper composition, they're brazed to the little arms that hold them, and showed practically ZERO wear when examined under  20X magnification.

This is the entire armature for the motor. The centrifugal switches are on the left, and the commutator on the right:

 Yep, the commutator is filthy, grooved, and not as "flat" as it should be. This is the same as on a starter motor for a car. That operation is called "cutting the comm", "turning the comm", or other phases I forget. For a starter motor you chuck the armature into an "Armature Lathe", and use a cutter to refinish the surface.



This is a whole bunch more delicate, so I chucked the motor shaft into my cordless Dremel tool, ran it at the lowest speed possible, and used a strip of 2000 grit sanding film to clean it up.

Again, these aren't my pictures, but this is essentially what I did:

After, but mine has a more uniform nice, bright copper look on all the surfaces:

These are the contacts for the two centrifugal switches. Just clean them gently with a strip of paper, and DO NOT adjust them, or you'll turn the motor into a paperweight:

SO....after spending a week diagnosing this, then taking the transport apart again to pull the motor, rebuilding the motor and reinstalling it, and finally putting the entire transport back together The Verdict Is.....Problem Resolved!

It now stays in play, the voltages across the motor are by-the-book, and Fast Forward/Rewind blast along MUCH faster than they did before.

Tomorrow's installment will be "Those Pesky Pinch Rollers, and What to Do About Them".

Wednesday, August 10, 2022

Still Tinkering on the Pioneer CT-F950 Cassette Deck

 Kinda shot myself in the foot on one section of this.

These are the "Pinch Rollers" that hold the tape to the Capstan, and pull the tape through the machine. This is the OEM unit, and you can see the wear on it. Yes, they're tiny.

The replacements I bought were just rubber sleeves to fit over the bronze "Oilite" bearing. They came with ZERO instructions, and required you to press off, or otherwise remove, the OEM rubber from the bearing. OEM assembly on your left, removed from the arm it normally resides in, and the new sleeve on the right.

I pressed the bearing out using two properly sized sockets and a small machinist's vise:

BUT.....(always a "but", eh?) I neglected to scrupulously clean the bronze bearing of all traces of the original rubber. The stuff would NOT come off easily, and it may have been vulcanized on to the bearing. I cleaned off as much as I could, pressed the new sleeves back on, and put it all back together.

 I moved it from the "Mechanical Bench" over to the "Final Test and Adjustment Bench".

It randomly dropped out of play, so the testing stopped until I could address that. It would Fast Forward and Rewind properly at a high speed, but sometimes it would play for 2 minutes, sometimes for 10 minutes, but it always dropped out. It was dropping out because the Reel Motor, that motivates the Supply and Take-Up reels inside the cassette  was stopping. When that happens, the tape counter no longer functions, the controller sees "No Tape Motion", and drops everything offline. When it stopped you could always see some slack tape over on the take-up side, which is what clued me into the Reel Motor being flaky.

Using a search of the forums I found several threads on this, and followed their troubleshooting guide. Measured the voltages recommended while trying to play the unit, and those measurements confirmed the Reel Motor needed some serious servicing. Turns out it's quite common in these 40 year old Pioneers. New motors are NLA from anybody, and the ones from a parts unit would be highly suspect. They can be refurbished, however, so I read and re-read the instructions, and printed them out so I could go into the little electric motor and do the work. It's about 75% bigger than the "Mabuchi 540" motors we used in out slot cars, so it didn't bother me to do the work.

I'll go into the "Reel Motor Rebuild" tomorrow, and then back to those pinch rollers.

I'm about 99% finished with the mechanical stuff at this point tonight, and when I button it back up (again....) I can continue on the electronic adjustments, and whoo-boy....there's a whole slug of them to check/adjust.

Friday, August 5, 2022

Welcome To The Weekend!

 And we're off to the Larimer County Fair!

Photo crew will be SLW and my son. TLG has been talking about it all week....

Have fun and be safe out there!

Tuesday, August 2, 2022

RATS! Bought Wrong Chains for My Chainsaw....


 Oh, I understand the difference between .043" pitch, and ,050" pitch. The new chains wouldn't slide easily in the bar, and it drove nuts until I did some googlin', and looked at Gen-You-Ine Makita chains vs the Brand-X chains I bought at Cheapo Depot. The Brand-X chains were poorly marked, and had no "Also Fits" guide on the package. Rookie mistake, I guess.

Proper chains on the way, and I can finally finish cutting up all the logs in the backyard. I'll go rent a splitter later in the year so I can turn them into easily digestible sizes for the fireplace.

The OEM chain got severely dull from cutting out some of the dead juniper bushes earlier this year. Cutting that stuff is like trying to cut steel.....tougher than snot, and rapidly dulls the blade.

Pioneer CT-F950 Reel Motor Rebuild

 As I mentioned yesterday, the first electrical issue I ran across in rebuilding this deck is that it kept dropping out of Play. A bit of sl...