Hitachi D-900 repair help

[SolderSplash]

I recently found about a dozen pieces of audio equipment in a property I acquired. I hated to see them just go to electronic recycling, so I thought I might try to get some of them working again. I've got some electronics background, so How Hard Could It Be? ™

The first piece was a Magnavox 8-track/tuner/amp POS:

For some reason, the speaker outputs are RCA jacks instead of screw terminals or clips. What's up with that?

It actually went pretty well. The belt was goo, the wood-grain vinyl was peeling, the selector switch was gummed up, and the stereo beacon was burnt-out. I couldn't find an 8.3V 0.3mA replacement, so I dropped in a warm white LED. It looks and works much better:

Ok, that was fun. Next, I thought I'd tackle one of the cassette decks. How about this Hitachi D-900:

Purty! And inside:

Gaah! cogsinister's excellent post on replacing the belts on his unit is what led me here.

I've got the belts replaced, but the take-up spindle doesn't have enough torque. PLAY seems to work: head assembly rises, the capstans pull the tape through, and the counter seems to advance as long as the spindle turns. But as soon as the take-up spindle slips, the tape starts to pile up after the right capstan.

There is only one motor, and there doesn't seem to be any kind of idler wheel, so I'm guessing there must be some kind of clutch mechanism inside the gear assembly:

This assembly is listed as a single part, #40 in the SM (click to zoom):



There are two pieces called the "AS LEVER" (#43) and "AS PREVENTION PLATE" (#45), further toward the front tape compartment that might be related. Is there something else I should be looking at? I think I'm down to removing the gear assembly to see if some part is gunked up.

Other info:

* Manually pressing the PLAY solenoid lever (#69) seems to move the head assembly into position correctly, but the take-up spindle still slips when turned manually.

* REW works fine, but FF does not activate the solenoid. I haven't checked the buttons or solenoid yet.

* When idling (STOPped), the green and blue parts move a smidgen, cyclically:

* When I turn the take-up spindle manually, the red part slips in the green one.

Besides continuing the disassembly, I'm not sure if there's anything else I can try. Suggestions anyone?

Thanks,
SolderSplash

 

[trinhsman]

I know you want to get this working, but based on my experience with Garbachi, I would suggest throwing it away. Don't mean to sound rude, just another venting I do from time to time when I see something on a problem with Garbachi gear. And yes, I did have a very bad experience with them and they were horrible to deal with. Will never own another piece of their stuff again......Sorry about the rant.

 

[SolderSplash]

heehee... After looking at the carefully crafted interior (a joy to behold!), I don't know how you can say mean things like that.

OTOH, you may have saved me a lot o' trouble.

 

[GerardG]

Hitachi tape decks are a PITA. My tech had my D-720 (a little older but very similar deck model) a year and had all sorts of trouble to get it to function. It came down to a small spring that was out of place because of a previous tech's repair attempt. The deck was my father's who had it repaired after several years of service. Even after that "repair" it never worked and was put away for decades. Anyway, my tech discovered this spring misplacement after a friend of his tracked down someone who had worked on these fairly rare units back-in-the-day and who offered advice as well as a service manual.

All that said these decks sound amazing! You'd be hard pressed to find anything as good sound wise. It beats my Akai deck as well as my Denon decks of which one is a three heard unit.

If you can figure it out it may well be worth the effort. Besides, isn't it a beautiful looking deck?

Gerard

 

[SolderSplash]

Besides, isn't it a beautiful looking deck?

I do really like the appearance. And it's in perfect condition, which (I hope) makes it sellable. My concern is that I'll put a spring back in the wrong place. I hear that's happened before...

BTW, I just read that the Realistic SCT-30 is a rebranded Hitachi D-850, which appears to have the same transport mechanism as the D-900. Two more things I can search for to glean information about this rara avis.

Thanks!

 

[comish4]

If the 850 is in working shape that also is a great deck.

 

[SolderSplash]

Man, it was a real struggle to get this working! It turns out that one of the plastics used in the transport mechanism has a shrinkage problem. In most places, it's not a big deal, like on the outside of the Gear Assembly:

Where it did matter was on the take-up spindle clutch:

That center piece, a "dog clutch", is friction-fit on the axle. Because of the shrinkage, it fractured in three places:

And that explains the lack of torque. Somebody else had a similar problem, and I followed what they did: wrapped it with thread and applied some glue:

Now it grips the axle tightly and transfers torque to the take-up spindle.

Woot!