Wow… that’s quite a find! I wonder how many of those car-stereo units were actually made, and if any of them were ever sold here in the USA? I don’t recall ever seeing one over here, not even in any of the shops specializing in high-end car stereos…
From what i just gathered the controller PCB next to the capstan motor does not give power to the capstan motor… This may conclude this small PCB being dead…
Yes ive seen that topic, fortunately mine will load a tape it just refuses to switch the capstan motor on.
So my next idea was to power up the motor via another 5v line, but to my surprise it still didn’t spin…
So the motor seems dead too, possibly the cause of the failure on the Control PCB. Not to be defeated by a DC motor i popped the lid of, what i found was that the motor brushes where completely gone!
The length is good, the few mm of extra length wont cause a problem here, but the base is a bit to wide, nothing a little visit to the Dremel cant solve.
So putting the “new” brushes in and testing the motor by supplying some power directly to the brushes confirmed i had pulled of a sucsessful repair
But, putting the motor in the DCC it still didn’t turn… This makes me think the speedregulator inside the motor most likely is broke too.
But what if i connect my lab bench psu to the motor directly and turn the radio on, the first test on ACC proved that it worked! But now came the task of carefully setting the motor speed so it would play a DCC, and it worked!
There is no schematic online for the DCC822 and I’m stunned that you were able to play a DCC without speed control.
FYI even if you can’t find a matching motor controller, it shouldn’t be too hard to replace it with another one. The speed control circuitry probably generates a duty cycle signal that can simply be amplified and fed directly to the capstan motor. That’s what the other decks do anyway.
I hope you can get it to work. The 822 is a great player; it even shows lower case text that you can enter using DCC-Studio and the DCC-175.
So ive made the choice to restore the whole radio, for this i used a DC722 for many parts and buttons that are damaged on the DCC822.
First of all i replaces a few switches on the front panel which seem to fail more often on these range of radio’s. But before i could i had to take of all the old deteriorated foam.
After scraping off the old foam and replacing 2 switches it was time to replace the foam with a replacement found at the hardware store. This foam is used to keep the buttons in place.
TDA3611/12 is a Philips deck controller IC used in many cassette decks, not just DCC! The problem comes in the packaging, on the DCC control PCB it seems they used the bare chip and covered it in epoxy. While all the other TDA3611’s come in a DIP24 package.
The solution may be to design a small secondary PCB housing the TDA3611 and that can be placed inside the radio and connect via a ribbon cable
Last few evenings i spend reverse engineering the rest of the control PCB. There is a small circuit that resets the Microprocessor on the DCC deck, either from an external source or the insert switch