PS- 3300 Platter keeps spinning, won't power off.

[RockProspector]

Hi, sorry to resurrect an old thread :mrgreen:

I've just been given a broken PS-3300 by a friend, it's got a few faults with it, it won't power off because the micro-switch never gets made, I ran it with the cover off and pressed the micro-switch by hand and it powered down jut like it should so I know the switch works. The return isn't adjusted in the right position so the arm gets to the end before the end of the record

Both of those issues I can fix with adjustment, my main problem is I'm missing the plastic gear that goes on the spindle so the arm never returns, just reaches the end and stays in the middle, does anyone know where I could find that part, or if it's even possible to find?

Thanks

[RockProspector]

No replies? then it would seem that the part is unobtainable, my research finds the same #-o

Never mind, I'll go back to that in a bit

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This thread has been so helpful to me with all the other faults that I feel like I should give something back, so here's a tutorial on how to replace the microswitch: (I first said my microswitch worked, and it did for just long enough to set the clearance just right, then it gave up :? )

1.) Take the metal platter off the spindle, then remove the spring clip from the return gear (the big nylon one) and take that off

2.) Remove the motor mount screw closest to the back, take note of how long it is and loosen the other two as far as you can without the motor dropping inside the case. Motor mount screw locations:

https://i.imgur.com/qksoWLD.jpg

Then take the stylus off so it doesn't get damaged, leave the arm unclipped and free to move, close the top cover and turn the whole thing over

3.) The back cover needs to be taken off (instructions for that can be found earlier in the thread)

4.) Next the microswitch leaver assembly needs to be removed, for this you will have to take off another spring clip and one spring:

http://i.imgur.com/2GpPjMQ.jpg

It's easer to take the spring off the case than off the lever, the case has more than one hole so mark the hole the spring is hooked through, you might have to bend the hook a bit to get it off, once that is done the whole lever assembly should be able to removed, with the motor loose the return drive lever should fit out behind it. Here's what the gap underneath the motor should look like:

https://i.imgur.com/14Auff4.jpg

you will have to rotate the lever that's attached to the arm out the way (why I said leave the arm unclipped) once the lever assembly is out it should be attached to the deck only by the microswitch cable

5.) Remove the microswitch from the lever assembly: (two Philips screws)

https://i.imgur.com/tjgQItx.jpg

And the Leaver assembly, whilst this is out you might want to clean off the dry oil and re-lube it with some light lithium grease:

https://i.imgur.com/WG6yOSK.jpg

I expected the microswitch part to be almost impossible to get, turns out its a standard omron switch, the design has changed a bit over the years but the hole spacing is still the same and the new version (omron SPDT-NO/NC pin plunger microswitch, 5A 250V ac) is compatible

6.) Fit the new microswitch, on my deck there was a loop of excess wire so no problem with cutting it back about 1/2” instead of undoing the sleeving. Then solder the new one in place, I used heat shrink sleeving. The pin layout on the new switch is different, the switch should be normally closed, here's the pin layout for the original and the new switch:

https://i.imgur.com/FC0MwzQ.jpg

and the new switch wired in:

https://i.imgur.com/XlFycpv.jpg

7.) Refit lever assembly, exactly the same as taking it out just in reverse, at this point you need to adjust the switch clearance a bit, the new switch is very slightly different (instructions for that can be found earlier in the thread, however the previous pics with the adjustment screws labelled are labelled the wrong way round, I'm not trying to get at anyone, just save to time for anyone else trying this task. The return adjustment is the hex screw and the microswitch clearance is the Philips screw) And I admire the people who completed this with the deck balanced on books, that was just to tricky and I had to come up with a different solution:

https://i.imgur.com/vv8SCHH.jpg

with the deck on wood G-clamped to a bench there's no risk of it falling off and damaging anything and you have complete access underneath

While the deck is open I also cleaned the dry grease from all the other mechanical components, and cleaned the pots with switch cleaner, now at least the speed is constant even if it still wont return

Note: When refitting the return gear assembly the cam slot in the underneath of the gear needs to be engaged on the end of the microswitch lever assembly:

https://i.imgur.com/YbxCABd.jpg
https://i.imgur.com/ijX1NNg.jpg

Average disclaimer: Electricity is dangerous, don't try this unless you know what your doing and I take no responsibility for any accidents that result from this task

I hope this is useful to someone :mrgreen:

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And now I return to the missing gear, you can see what's missing in my photo of the top of the deck without the platter, I've given up on the possibility of being able to buy the part, however I'm a production line maintenance engineer and a machinist. I'm considering attempting to make the gear, the thing is it's a bit difficult to make a part when all you have to make it from is the measurements of the empty space where it once was. If anyone here has a PS-3300 and would prepared to measure some dimensions then that would be amazing 8)

Any of the following would be of great help:

The tip diameter (from the top of the gear teeth)
The root diameter (between the gaps of the gear teeth)
The number of teeth

Thanks

[Chiltern]

I'm sure that I have such a gear, don't throw much away.

PM if required and I'll put it in the post.

Alan

Turntable auto drive gear.jpg

(83.47 KiB) Downloaded 54 times

[RockProspector]

I'm back 8)

Still not had time to look at replacing/making the gear (Chiltern was an amazing help with trying to find a new part) and this project is turning into a big one :D

When I tested it with a new stylus the record deck played well but I had a lot of unwanted interference, most was fixed by replacing a damaged wire between the kettle lead socket and transformer where I think there was some arcing, the signal quality is still terrible and crackles if I touch the phono lead so I guess I need to replace that (I already tried cleaning and tightening the connectors)

I have a low capacitance phono lead with a ground attached and was going to use this, then I read that I should use silver solder, how critical is this? can I get by with normal solder?

[RockProspector]

My project is finally finished :D so I thought I'd better post an update:

The first step of making the gear was to work out the dimensions, I made the hole sizes match the OD's of the shaft while ignoring the spline so that the gear could be easily slid over the top and glued in place with epoxy resin, I made both parts from nylon. Here's the dimensions I worked to:

For the gear:
Width: 0.275''
Tip Diameter (from the top of the gear teeth): 0.725''
Root Diameter (between the gaps of the gear teeth): 0.620''
Number of teeth: 20
Hole size: 10.9 mm

For the cam like thing that the lever engages on (whatever that may be called?):
Width: 0.150''
Diameter: 0.700''
Height of key that engages on the lever above the diameter: 0.100''
Hole size: 10.3 mm
(this was just cut from thick nylon sheet with a jewelers saw and a file)

https://i.imgur.com/ziT5oYW.jpg
^Shows the spline, where the gear should sit, and the flat section before the taper starts, where the cam like thing should sit. If anything (even glue) extends above the flat section the platter won't engage on the taper correctly

https://i.imgur.com/lANZe6o.jpg
^Shows the two parts of the gear assembly before I pinned and glued then together

https://i.imgur.com/Skwil6F.jpg
^Shows the completed assembly



disclaimer: I can't guarantee accuracy of the dimensions quoted above

[Chiltern]

Excellent, how did you produce the gear?

Alan

[RockProspector]

Excellent, how did you produce the gear?

Alan

Thank you :D I don't think I could have done it without the gear you sent me, it was the wrong size but it still gave me a template for the shape of the part that engages on the lever, since I had nothing of the original part at all it would have been tricky to come up with something that would have worked

I cut the gear on a milling machine using a dividing head, it looks a little rough because I didn't have the correct cutter so I had to file the gaps between the teeth very slightly larger

[lenjack]

Amazing thread, but don't you guys realize, that when you have a platter that wont stop spinning, you've discovered the world's first perpetual motion machine ? #-o =P~ =D>

[RockProspector]

Amazing thread, but don't you guys realize, that when you have a platter that wont stop spinning, you've discovered the world's first perpetual motion machine ? #-o =P~ =D>

Now I wish I'd worked that out before I fixed it :( :lol:

[lenjack]

You'd be a billionaire.