Sony TC-K770ES - Help needed

There is anywhere a broken tooth from a gear for tape transport (between reel motor and reel gear for cassette transport - go to page 43 service manual)). This kind of relacement parts are no longer available. Therefore I am looking for the same model in not working condition.
But above mentioned model is too rare.
Therefore I want to know, which other models from SONY uses the same cassette transport mechanism.

Maybe one of the member know this.
Thank you very much for advices.

Serv.-man. of this model is here:
SONY TC-K770ES SM Service Manual download, schematics, eeprom, repair info for electronics experts
 
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Measure the gear's module and see if its available - if its a gear/sprocket pair you can possibly fashion one by supergluing a gear wheel and sproket together?


Its very likely to be metric module for a Japanese part. Fine pitch gears are not going to be printable on cheap 3D printers, note, nor laser-cut (which is another approach to gear making)



Basic Gear Terminology and Calculation | KHK Gears
 
You mean that tiny gear on the left upper motor for coiling / rewinding the tape ?
I've inputted the number from the Service Manual onto Google and there was a guy on Ebay who sold me new ones printed in 3D. X-3363-501-2 or X-3365-377-1. Actually he listed them with the wrong number from the capstan motor. Check if they are the same. Mine are for a TC-H5900 but it could be the same mechanism. It is working fine. Restored two decks, mine and my brother's.
 
You mean that tiny gear on the left upper motor for coiling / rewinding the tape ?
I've inputted the number from the Service Manual onto Google and there was a guy on Ebay who sold me new ones printed in 3D. X-3363-501-2 or X-3365-377-1. Actually he listed them with the wrong number from the capstan motor. Check if they are the same. Mine are for a TC-H5900 but it could be the same mechanism. It is working fine. Restored two decks, mine and my brother's.


Thank you for this input.
Unfortunately, I don't know this exactly, because between the reels and the gear for reel motor are working several other gears.

To find out the faulty gear exactly, I would have to investigate all suitable gears.
This means completely disassembling and assembling everything, then ordering the suited gear.
Then completely disassembling and assembling everything again for replace.
But this effort is too extensive for me.
Therefore the question in post #1 to find a cheap device with same mechanism.
If I have this, only a single disassembling and assembling is necessary.

But maybe that gear at reel motor with part No "X-3365-377-1" is the broken gear.
While operating (fast forward/rewind so as play) there is to hear a peak noise
resp. a crack, that occurs in an interval - even without a cassette.

This links are of interest:

Sony X-3363-501-1 Gear - FiXAMENT
SONY X-3363-501-1 replacement gear for TCM-190 transport. | eBay
Sony TC-K490 eats tape + broken screw mount post - Tapeheads Tape, Audio and Music Forums
 
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Yes the first one worked on my decks.
If Your deck eats tapes this is the one.
This gear also controls the other functions. It rotates the larger cam gear.
That means, sometimes it plays but doesn't stop (cassette door doesn't open because heads doesn't descend) or doesn't rewind etc.
It is not difficult to disassemble, but requires patience.
Unscrew the three screws and the plastic back comes off with the reel motor and gear. You'll have to remove the PCB's first.
Be careful to let the cam in the neutral position before assembling. Take a picture from the mechanism first. You can test simply by rotating freely the capstan flyweels.
When You press from the side the other gear attached to the broken one, the cam begins to move between operating positions.
You have to put the belts on the pins surrounding the reels and then slide them to the gears after assembling like in the manual.
Uppon assembling the plastic back, must rest with no force on the mechanism, so if You have to make some force, check if those gears aren't overlapped (not teeth engaging). If they are use a tiny screwdriver to push them to the correct position before resting the plastic back. The hooks on the clutch are helpfull for this.
I don't think You are going to find a new mechanism. Check also if the large cam axle where the screw attaches enters the plastic back.
I had attempted to repair it before. First I've glued the broken gear but it didn't last long.
It is working like new after lubing and replacing belts. Now I will buy a calibration tape in order to calibrate the speed and azymuth.
One deck stops two seconds after the other, so speeds are identical on both and calibrated by ear and comparing using a DJ console, but I'm not sure if my ancient Pioneer CT-606 was recording at the correct speed. I don't have tapes recorded on other decks.
 
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Thank you for this service hints.

Now I have find out the mechanism type (TCM200 series) and thus several Sony models with the same parts arround the reel motor gears - go to
X-3356-638-1 Sony Motor (Reel) Assembly(mmn-6f2
X-3371-429-1 Sony Motor (Reel Rm) Assembly
Sony's ES u. Esprit Zeit Thread, Hifi-Klassiker - HIFI-FORUM (Seite 220) (scoll down)
Next step will be looking arround to one of this models for low cost in faulty condition for getting parts.
The deck under
Sony TC-K620 - Manual - Stereo Cassette Deck - HiFi Engine
I have order now from a private user in Germany.
Even according the service manual same part numbers arround the reel motor are mentioned.
I will report about the results as soon as possible.
 
Contrary to my origin intention I purchase a TC-K570. This was yesterday arrived. First step was repairing this deck - only the voltage regulator for the Capstan motor was faulty - replacing a 13V zener and additional new belts so as cleaning led to a flawless operation.
Now I dismantled the TCM-200 from the TC-K770ES
The cause of the in post #1 mentioned error was the gearwheel "Communication C" 3.356.703.01 (service manual TC-K770/570, page 44/32, No. 216/168 from exploded view).
After interchanging this gear weel and the motor board with both motors (reel motor and loader motor) from the TC-K570 to the TC-K770 the error went to the TC-K570.
The actually reason was that at the defective gear wheel had stuck in a groove a wire residue - go to the attached images.
Now I note no constant speed due to leaked electrolytic capacitors in the capstan motor control (inductor-) PCB. This images you will find in the next posting.
 

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Replacing leaked SMD electrolytic caps

This was very difficult, because the solder joints was oxidized.

After carrying out the replacement with wired versions, a perfect operation without speed fluctuations was observed.
 

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some additional images from this transport mechanism from Sony.

The designation of the photos can be found if you log out.
 

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