Sony PS-D707P Problems

['LIVEWIRE?']

Two, to be precise. (1) The turntable motor won't switch off, so I suspect the leaf switch isn't being opened when the arm is returned to it's rest, and,
(2) The Cam Gear is stuck and won't rotate, although the T/T plays records of both speeds perfectly well in manual mode.
I've downloaded the service data from Vinyl Engine, but cannot see what is causing either problem, even after removing the metal plate containing most of the mechanism. A small square plastic part was loose inside the player, but I can't see from where it came. It could possibly be a tab which opens & closes the leaf switch, I guess. The exploded diagram isn't brilliantly clear, but I will study it again.

['LIVEWIRE?']

Further examination shows that the Cam Gear was jamming because the gear on the centre spindle wasn't engaging that on the cam. It appears that the centre spindle c/w gear has to be lifted when re-fitting the cam gear, then lowered into place so that the teeth mesh correctly. The centre spindle is only held in place on its mounting post by some thickish oil, there being nothing to hold it in the correct position other than friction (if that's the right word?). I may try fitting washer(s) under the centre spindle to raise it to the correct level. Perhaps a ball race such as BSR & Garrard used to use would be a good idea?

[ekjdm14]

Have you any photos of the area (the actual player and perhaps the relevant part of the service book if allowed)? It doesn't sound quite right that the gear should just "float" and rely on the viscosity of the lubricant to hold it in mesh. Perhaps there is a bearing or spacer missing.

The ball "wafer" bearing idea sounds like I would have expected to find & possibly a good solution if the cause is wear or damage.

[Likeoldthings]

Hi

Sorry to butt in but I also have a problem with the Sony PS D707p shaft and cog.

In my case the cog has split and slid down the shaft leading to the problems you describe.

Be very interested in any resolution you find, as usual with Sony the part A-4604-892-A Shaft Assy Centre is NLA.

Its part 55 in the service manual.

Cheers

Ian

['LIVEWIRE?']

I'll take some pictures, maybe tomorrow, and post them on here ASAP. As to the ball race/thrust washer idea, I may have a spare Garrard one somewhere, but whether or not it will fit the Sony shaft, I know not. In the meantime, the diagrams & parts list for the 707 do not show any additional washer(s) underneath the centre spindle-the whole thing is shown as one assembly.

[ekjdm14]

I wonder if the gear should in fact be fixed to the spindle and has a hairline crack on your TT as well Livewire? ?

If that is the case (ageing plastic gears have to be the bane of my life, got a split one in my Ferguson cassette deck too!) then perhaps judicious application of superglue would help, or to be more extreme perhaps drilling/tapping the spindle and gear for a grub screw.

Edit- just downloaded the service manual myself for a look. It really isn't very clear is it! Photos would be great as I can't make out from the exploded view what is even supposed to turn and what's supposed to be fixed! It looks like the shaft with the small gear is fixed to the plate with a nut and washer. but surely would need to rotate. My only guess at this point is the shaft assembly 55 has some sort of bearing between the bottom section and the gear/upper part. Still my best guess at this point would be a fractured gear sliding on the shaft when it should be fixed.

['LIVEWIRE?']

That thought did cross my mind,ekdjm14, Time permitting, I'll have a closer look at the centre spindle assembly tomorrow. It's basically in two pieces, with the actual TT spindle fitted over an inner spindle which is bolted to the metal base plate. The gear wheel appears to be a push-fit onto the spindle, so a hairline crack could have caused it to move downwards. There's no visible bearing on the assembly 55 in my Deck. As to drilling and fixing the gear with a grubs-crew, I don't possess a drill which would penetrate the highly polished (chromed?) turntable spindle. In the end it might be less trouble to remove either the cam gear or the one on the spindle, so that the deck works purely manually! Working on this model makes me think that, the use of an aluminum platter aside, the 707 is basically similar to the various Chinese made decks available today, using the same type of small DC motor and, in the case of the 707, an all-plastic straight pickup arm. In fact i have a 'Neostar' music system, including a CD burner,which has a belt-drive deck with an 'S' shaped arm, pitch control, and detachable head shell which performs just as well as the Sony, and is only let down, IMHO, by the small built-in speakers. Admittedly I only use the Neostar to burn CDs from various sources, and use my TEAC PX300 DD Turntable for serious listening to LPs, but I thought it worth making the above comparison. The arm on the Neostar, b.t.w., has a properly adjustable counterweight. It can be balanced, and have it's tracking weight set to anywhere between 0 & 5g., so, as the head shell is a standard type with 0.5" centres, almost ant ceramic or magnetic cartridge could be fitted, which is more than can be said for tha arm on the Sony deck!

[ekjdm14]

Now that's a bit of a change from Sony's usual rep for making decently solid stuff. I have to admit I don't particularly like belt driven/DC turntables as they just don't "feel" right compared to synchronous motor/idler driven.

The Neostar on the other hand, sounds like a cut above the Sony in it's functionality (speakers excepted) and certainly better than the general standard of modern turntables.

['LIVEWIRE?']

The Neostar does perform O.K. I was offered it a few moths ago, and only took it because it made burning CDs easier than using the PC. It has a decent 3-waveband radio, a basic cassette player, plus other features, and, with a few mods, could actually be at least as good a performer as the mid-range music centres of the 70s/80s, IMHO. As to the Sony 707, it was one of a range of turntables they produced back in the early 90s to go with the 505 & 707 series stack systems, so no doubt 'built down to a price' Other Japanese firms such as Pioneer, for one, also produced similar record decks at around the same time. I'd better stop here before going too far OT with this thread!

[Michael Maurice]

These plastic cogs are supposed to be an interference fit onto the spindle.

If you are going to refit the cog to the centre spindle, may I suggest you file the inner bit of the cog just a little bit so that it fits easily onto the spindle without opening up, (where the crack is) then glue the cog to the spindle using an epoxy resin. I’ve found Araldite metal to be very good, especially as JB Weld is no longer available in the UK and Europe.

['LIVEWIRE?']

There is indeed a crack in the plastic cog, so thanks, Michael and others, for pointing out the possibility. I may try using Araldite Metal to secure it. There is no way that I can see to drill a hole for a grub screw without damaging the teeth of the cog. In the meantime I've taken a couple of photos of the centre shaft assembly and will post them here later.

['LIVEWIRE?']

As promised-pictures of the centre spindle assembly, the second hopefully shows the hairline crack in the plastic gear. The assembly consists of several parts, basically the outer spindle on which the T/T rotates, an inner shaft with a Molykote or similar lubricant between the two, the plastic gear, and the threaded fixing shaft with fixing nut and washers. None of this is abundantly clear from the drawing in the service manual, where it is simply listed as 'Item 55, A-4604-892-A, Shaft Assembly, Centre although the washer9s0 spring washer, and nut are listed separately, item 66 being called 'Washer, rain!'

[ekjdm14]

Ah yes, the fabled rain washer! that gave me a chuckle too.

Michael's suggestion of opening out a small "keyway"/relief on the inner surface of the cracked gear & fixing it back in place with chemical metal would seem to be the best long-term solution. Obviously this gear will have some sort of loading, however small, through it when operating the trip so superglue probably wouldn't last & the grub screw idea would be more suited to something higher-end intended to last another lifetime so as long as it's fixed back at the correct height & the crack is held closed while it sets that would get it back to full functionality.

Edit- you'd be surprised at how easy to drill the spindle may have been, given a decent centre-pop to start you off. It looks to be made of Brass with nickel/chrome plating, although as you say it'd have to be a tiny hole to avoid interfering with the gear teeth. I recently drilled out a broken pin on a Garrard overarm, and fashioned a replacement from a stainless woodscrew. All freehand too, although it would've been a lot easier with a small vice.

['LIVEWIRE?']

I have removed the cracked gear wheel from the TT shaft. The deck works perfectly in manual mode without the gear. So far the motor switch is working as it should, by moving the pickup arm to the right the motor is switched on, and when the arm is returned to it's rest, the motor switches off, so I may leave it like that.

[Techman]

I've found this same problem with regards to Sony decks. Whether it's particularly a Sony specific 'plastic' problem, or it affects other makes and I just haven't come across it in them yet with this style of deck, I don't know. I get round this sort of problem by winding bus bar wire of the appropriate gauge around the broken or cracked piece and tightly winding up the ends with pliers. With that part that you have, I may make a small indent all the way round with a fine, round needle file before winding the ring of wire round it.

As time goes on, we're going to be dogged by more and more of these plastic degradation type problems - that black plastic star wheel on those BSR decks which seems to shrink (or expand) on its shaft, causing pickup arm return set down problems, being just one example of many.

['LIVEWIRE?']

I haven't come across the cracked gear problem on other makes of deck, but I have a Pioneer PL-J210 turntable, which uses a similar mechanism, with a plastic gear on it's turntable center spindle, which was O.K. the last time I used it.

[ekjdm14]

I think Sony in particular may have some plastic quality issues, I believe there's a common failure in the tape loading mech of their VCRs which is down to a broken gear, certainly very common of their S-VHS and maybe VHS too.

As I mentioned before, I do have issues with degrading plastic gears on the cassette deck in my Ferguson 3926 & have had plenty of other problems with plastic degrading over time too.

I can only see this becoming a bigger thing in the future as more-modern equipment comes back from the "just an old radio/TT/stereo etc" doldrums to being collectable. I think storage conditions have a big effect, second only to whether the material is just prone to degradation. Lots of heat cycles/sunlight/atmospheric pollution/oil based lubricants all take their toll & the net result is we will, ultimately, need to devise ways of repairing or (ideally) replacing these things when they fail. I think there's a lot to be said for 3D printing in this respect, at least for reproducing blanks to be machined from or for moulding in other materials.

[TonyDuell]

Plastic mechanical parts, particularly gears/pulleys press-fitted onto a spindle, often break. I don't think this is a Sony-specific problem.

I had the counter pulley in a Philips N4510 crack radially (turned a metal replacement and fitted it with a grub screw). As for gears, ones that I have had fail (from memory) include

Several small pinions in FischerTechnik motor gearboxes

The stepper motor pinions in Alps 4 colour plotters (the mechanism used in the 4 colour printers that everybody seemed to make in the early 1980s)

A gear in a Xerox telecopier (a 1970s analogue fax machine) just broke up. I was lucky here, the tooth pitch turned out to be the same as one used in radio controlled models, so I could get gears that would mesh correctly with the other parts and just had to turn a hub for them.

I am not convinced that 3D printing is a solution. The general view of machinists that I know is that with the current state of the technology the parts have a very poor finish and are not that strong. You are better off machining the part from solid (even though it takes longer). This might change of course.