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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 3rd Oct 2016, 10:57 pm   #1
ukcol
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Default Midi Hi-Fi cassette decks repaired.

Flushed with the apparent success of sourcing an original laser pick-up assembly at an economic price for the CD in my pal's early 1990s Sony HCD-H1500 midi Hi-Fi (see here) we decided to look into getting the cassette decks back to life.

This machine employs two nearly identical micro-processor controlled auto-reversing cassette decks. The only difference between the two being that one is a record/playback deck and the other is playback only.

There is only one drive belt in each deck and both were in need of replacement. One had stretched to the point where it provided no drive at all and the belt in the other deck had rotted and fell to pieces; most of it had wrapped itself around the motor shaft under the pulley and had the consistency of hard sticky toffee. In my belt stock I had a kit of belts that I had bought from SEME some years ago and two suitable belts were found. After removing the old belts, cleaning up the sticky mess and fitting the new belts both decks started to work.

The next problem was that although both decks would perform rewind and fast forward there was no take-up in forward play mode.

Referring to picture 1, the gear arrowed is normally held in the position shown. In forward play it is allowed to move across to engage with the take-up turntable under the influence of a light spring. Picture 4 shows that the arm this gear is attached to is pivoted around the case of the forward capstan bearing. Unlike the reverse capstan the forward one is also used to drive the mode cam gear and some of the lubricant from the gear had got onto the pivot point arrowed. The lubricant is OK for the cam gear but too heavy for the take-up gear arm and was preventing it from moving fully across to the take-up turntable. I removed the arm, cleaned up the pivot area and refitted the arm. This cured the problem and the same work was done on the other deck with similar results.

When these decks change the direction of play the heads have to be turned through 180 degrees, on one of the decks this turn was not completing and was caused by sticky lubricant. A clean and re-lubricate solved that problem.

Picture 2 shows the back of one of the decks before the PCB and motor plate had been removed.

Picture 3 shows them removed but with both capstans still in place. I have indicated the approximate position of the motor pulley to give an idea of how the belt path works to drive both capstans.

When the decks were reassembled they both suffered from wow and flutter in play. All four pinch rollers were pretty poor and a thorough clean did not provide a complete cure. The original Sony pinch rollers come mounted on the pinch roller arms of 2 types (the reverse arms being a mirror image of the forward ones). I found a source of the original Sony parts but the reverse ones were just under £8 each and the forward ones more than 3 times that price. The pinch rollers are attached to the arms by jaws that hold the bearing pin and these can be popped out quite easily. I found some “AV1722” pinch rollers on Ebay that were 13mm in diameter with a 2mm diameter hole for the bearing pin. The “tyre” width was 6mm and the overall width of the wheel part 8.3mm; these dimensions compared with 13mm, 2mm, 7mm and 8.0mm for the original rollers. They were £2.65 each. The slightly smaller tyre width (6mm as against 7mm) was of no consequence and the 8.3mm wheel width was reduced to 8.0mm with the aid of some coarse glass paper; (I did try one with its full 8.3mm width but it was slightly tight). With the new rollers fitted the decks worked very well.

Unusually for a midi system the Sony has a phono input for a magnetic cartridge. I serviced my pal’s Technics SL-L20 and then we had a nice working system again. The Technics is a linear tracking deck and just needed a new belt and the arm guide bar cleaning; we also obtained a new stylus.
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Old 3rd Oct 2016, 11:48 pm   #2
Lloyd 1985
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Default Re: Midi Hi-Fi cassette decks repaired.

Nice work!

These auto-reverse decks are certainly complex things to service. I have been getting a few of Sony's FH systems up and running over the last few years, and a couple of nice Technics decks too. I've had no end of trouble trying to source new belts, what with not knowing the exact size of the original belts, and then ordering a kit for the FH-7 deck, only to find the belts that are sent are entirely wrong! I've been lucky with the pinch rollers, all of mine have needed nothing more than a good clean and a rub with wet and dry.

Regards,
Lloyd.
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Old 3rd Oct 2016, 11:49 pm   #3
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Default Re: Midi Hi-Fi cassette decks repaired.

Sony still made some decent stuff in the early 90's. That fact alone made this worth saving. Nice one!

Regards,
Paul
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Old 4th Oct 2016, 9:06 am   #4
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Default Re: Midi Hi-Fi cassette decks repaired.

Thanks for your comments gentlemen.

I am not particularly confident with mechanical repairs and this job took me ages. It certainly wouldn't have been a profitable job in a commercial context.
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Old 4th Oct 2016, 10:19 am   #5
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Default Re: Midi Hi-Fi cassette decks repaired.

Hats off to you from me too, Brian.

This was the kind of job I loved doing when I was young, free and single, when I didn't earn enough to buy nice equipment new, and when spares were readily available. A few evenings of hard work, a couple of quid on parts, and I had a really nice bit of useful kit.

But nowadays, life is just too short, working equipment seems to be available for nothing, and spares are NLA unless you can make a generic part fit.

Well done!

N.
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Old 4th Oct 2016, 11:29 am   #6
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Default Re: Midi Hi-Fi cassette decks repaired.

Quote:
Originally Posted by Nickthedentist View Post
This was the kind of job I loved doing when I was young.............
High Nick,

I grew up in the 1950s when we had very little money, partly because of the times and partly because my father had deserted his family. I used to buy old radios from church jumble sales and get them going and our first TV after my father had left came via a similar process. I used to get tremendous pleasure from getting something for (virtually) nothing. An added bonus was that my family and friends thought I was some sort of genius getting these complex things working. I wasn't of course, like any youngster who had a passion for something my young "plastic" brain learnt very quickly.

Quote:
Originally Posted by Nickthedentist View Post
But nowadays, life is just too short.......
I'm retired now so time is not such a problem. I am still busy all the time but mostly with the things I chose to do.
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Old 5th Oct 2016, 5:12 pm   #7
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Default Re: Midi Hi-Fi cassette decks repaired.

Hi Colin,

I've just replaced the belt on a Sony TC-V925E double cassette deck, from 1989, which seems to have exactly the same mechanics.
The R/P assembly was already OK, while the (left) P one had the sticky gummy belt. Fortunately, I managed to find a good replacement from my home collection of belts.
The sad thing is that the left assembly is only working in FF and Rewind, and the takeup reel does not move for the same reason as happened to you: the moving gear does not engage with the takeup reel gear.
Thank you very much for your description that comes right on the spot. If you can give me any more detailed suggestion (a PM if you wish) it would be VERY welcome !

Marco
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Old 5th Oct 2016, 5:42 pm   #8
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Default Re: Midi Hi-Fi cassette decks repaired.

Hello Marco,

Are you saying that you have done the work that I described in my first post?

In particular (and referring to picture 4) have you removed the lever (arrowed) that carries the take-up gear and cleaned off the lubricant from the lever and the chassis before re-fitting?

Last question - If you have done the above have you still got the no take-up in play symptom.
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Old 5th Oct 2016, 6:57 pm   #9
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Default Re: Midi Hi-Fi cassette decks repaired.

Hi Colin,

no I just re-assembled the deck, as I didn't have any clue as to why the small gears were not doing all the travel. Now I know why.
So what I'd like to ask you is 1) how to remove the flywheels, 2) how to remove the gears and "V" supports (just pull them ?) and 3) is there any "timing" to observe with respect to the big centre gear ? I mean just as when one has to replace the camshaft belt-chain in an engine ?

Thank you very much again !
Best regards

Marco
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Old 6th Oct 2016, 11:54 am   #10
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Default Re: Midi Hi-Fi cassette decks repaired.

Hi Marco,

I'll try to answer your questions.

1] How to remove the flywheel(s)

Remove the cover plate from the top side of the deck. This is not shown in my pictures but picture 1a shows the top side of the deck after the plate has been removed. There are 2 nylon clips (one either side) at the top edge of the plate and 2 at the bottom edge. Release the clips at the top edge of the plate, the plate will now pivot on the bottom clips allowing it to be removed.

Turn the deck over to remove the motor plate, motor and PCB. Refer to picture 2a. Unplug the head plug and pull the wires away from the clip. Leave the PCB retaining screw in place, the PCB will come out with the motor plate. Remove the screw just above the motor (the screw head is just out of sight in my picture). Once this screw is removed the motor plate can come away from the chassis at the top, pivoting on 2 nylon fixing hooks at the bottom edge of the motor plate. These 2 hooks can be seen clearly in picture 4a. The motor plate, motor and PCB will now unhook from these hooks and can be put to one side.

Remove the belt (picture 3a). Remove the washer from the top side of the forward capstan shaft and put it to one side. The deck should now look like picture 4a. There will be a plastic washer (or 2) at the bottom end of the capstan shaft. There is a good chance that it (they) will stick to the the bottom of the capstan bearing rather than come out with the capstan. If this is the case remove it (them) from the chassis and slip it (them) back onto the shaft.

There is no need to remove the other capstan flywheel unless you have a different problem to the one I had. *see note below.


2) How to remove the gears and "V" supports.

First of all do not remove the cam gear, there is no need and you will avoid all the problems associated with timing. I don't know what you mean by the "V" supports but I hope I will cover all you need to know.

Picture 4a. Lift out the take-up turntable drive gear lever (big arrow in picture 4a). The cam gear slightly overlaps this part but you will be able to get it past by lifting the cam gear slightly. Once the lever is out thoroughly clean the grease off the lever. Do the same to the deck chassis where the lever fits. Refit the T/U gear lever assembly. If you chose to apply a lubricant to the pivot point use a very light spray lubricant, not oil or grease.

3) Is there any "timing" to observe with respect to the big centre gear. Just repeating what I have said above, don't remove this gear then timing will not be an issue.

Reassembling.

Refit the capstan flywheel back into its bearing remembering to make sure that the spacing washer(s) goes on to the shaft before it is refitted. Fit the other washer (the one you removed first) back on to the top side of the capstan shaft.

Refit the belt as shown in picture 3a.

Refitting the motor plate is a bit fiddly and this is how I went about it. First engage the cam gear shaft (arrowed in picture 3a) with the associated hole in the motor plate moulding, then hook the bottom left of the motor plate into the left hand hook (picture 4a). Then hook the right hand side if the motor plate into the other hook. The top screw near the motor can now be refitted.

Refit the head plug (picture 2a) and hook the associated wires back into the clip leaving a loop between the clip and the heads to allow for head movement.

Now that the motor plate is back you will need to hook the nearest part of the belt path (to the motor pulley) around the motor pulley.

Refit the cover plate to the top side of the deck. Clean the tape path including the capstan shafts.

* Note. The reason I didn't have to remove the other flywheel was because the fault only effected the forward take-up, reverse was fine. This is because there is no gear grease anywhere near the reverse take-up lever that can contaminate it.

I hope you will find the above helpful; as I have said in an earlier post I am not that confident with mechanical repairs due to having had relatively little experience. But I hope this is not a case of the blind leading the blind.
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Last edited by ukcol; 6th Oct 2016 at 12:00 pm.
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Old 6th Oct 2016, 5:39 pm   #11
MarcoBerti
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Default Re: Midi Hi-Fi cassette decks repaired.

Hi Colin,

Excellent ! I've just saved this web page for the day I will be able to re-work my Sony. All I can say at the moment is a huge Thank You.

I hope to be able to add a post to this thread with my success story in the near future. Your description will surely be precious for other deck collectors on the web ! Have a good WE.

Marco
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Old 12th Oct 2016, 10:34 pm   #12
Phil G4SPZ
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Default Re: Midi Hi-Fi cassette decks repaired.

Great piece of work and an excellent and informative write-up. Well done Colin!
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Old 13th Oct 2016, 9:15 am   #13
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Default Re: Midi Hi-Fi cassette decks repaired.

Thanks Phil, very generous of you to say so.
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Old 18th Oct 2016, 5:43 am   #14
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Default Re: Midi Hi-Fi cassette decks repaired.

Brilliant bit of work there - must admit I enjoyed getting things working as a kid and even later when I was relatively well off - nothing beats the fun of working out why it won't go and solving the problem plus you get a nice bit of equipment into the bargain.

My two favourite stories are a tape deck and a sig gen. The tapedeck was suspiciously clean and unused but very cheap in a local 2nd hand store. Pulled it apart and the problem was a capstan drive had a loose set screw! Tightened it up and all was/still is great. The sig gen was even better - the poor owner had obviously gone just about ga ga trying to figure out why it had output at high frequencies but not at low - voltages and calcs were all over the circuit diagram. Turned out that the output lead had a break in the single coaxial core. Redone and working very well indeed.
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