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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 26th Dec 2018, 6:37 pm   #1
Sean Williams
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Default Sony U matic VO5850P - The resurrection

Ive got one of these monsters on the bench at the minute - fair to say, im well out of my depth, and have very little idea of what really happens inside a video recorder.

Initially the machine was described as dead and smoking.

Easily sorted that one - Exit stage left one Rifa suppression cap and a 2A fuse - end result the power supply now works.

I have also solved a problem with the cassette loading mech - everything was jammed up, once freed off it now allows the insertion and removal of a tape.

The machine laces the tape around the head - I have given the pinch roller a clean, and the capstan motor is now spinning - to start with, the capstan was just grumbling.

There have been intermittent issues with FFWD and REW, which seem a little sporadic - sometime the machine will rewind, but in all cases fast forward is fine.

The tape winding motor decided to throw it's hand in, and lock up completely - this wasnt an issue - I have three more machines to plunder for bits, so I pinched a motor from another machine..... Damn, that one is seized too....

I dismantled the motor, and found the cause of the problem - there was a build up of crud on the armature, once cleaned up, and reassembled, the motor runs fine.

Now onto problems that are somewhat beyond my comprehension.

When rewinding a tape, the machine "runs out of breath" towards the beginning of the tape - I have checked the tape, and both hubs run free by hand, as do the hubs on the deck = is this likely to be just a knackered drive belt, or am I looking for something more sinister?

When playing a tape, the machine seems not to be 100% reliable with regard to taking up the played tape - resulting in a huge build up of unspooled tape at the capstan.

Lastly (for now) when the machine does play back and behave nicely, the playback speed seems at least double speed or more - I do not have any video as yet, just relying on the audio track until I figure out a way of viewing composite video. Before I go looking for a fault that isn't there, is it likely that the original source tape was just recorded at a lower speed? or is there some clever video type stuff that should already know this, and adjust speed accordingly?

Does anyone have a spare Umatic tape with known good content - sadly I rather suspect the tape I have contains material that is not suited to family viewing, and as such would be better off in the bin.....

All suggestions gratefully received - I am trying to get a machine working to allow the museum at HMS Mercury to recover some archive footage they have.

Cheers
Sean
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Old 26th Dec 2018, 6:48 pm   #2
collisr
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Default Re: Sony U matic VO5850P - The resurrection

Hi Sean,

You're not testing in a well lit room with the machine top cover off are you? As the end tape sensors are optical , I had all sorts of wierd problems as a result of the machine getting confused by the light on my workshop.

Doesn't explain your capstan speed issues though.

Happy to discuss the little o know when I see you on Friday.

Rob
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Old 26th Dec 2018, 6:52 pm   #3
Sean Williams
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Default Re: Sony U matic VO5850P - The resurrection

Thanks Rob,

I have tried both lid off and on, having read about the optical sensing - I think that isn't at play here though - perhaps I will try with the lights out

Sure be happy to discuss these wierd things with you.

Sean
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Old 26th Dec 2018, 10:25 pm   #4
Sean Williams
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Default Re: Sony U matic VO5850P - The resurrection

Think I will have all the optical sensors out and clean them, and I think a full belt kit and new tyre for the idler will also be in order

Hopefully this will restore some reliable operation to the mechanicals.
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Old 5th Jan 2019, 11:14 pm   #5
Sean Williams
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Default Re: Sony U matic VO5850P - The resurrection

Taking a break from the Viewmaster, I am back on the U-Matic.

I've fitted a new belt kit and drive tyre on the FFWD REW drive wheel - this has improved the performance and speed of winding the tape from end to end fantastically.

I also have repaired the tape loading drawer - there was a broken wire on the cassette sensor - this meant the machine would tot take the tape in automatically.

I have one very odd problem however, that defies logic.

U-Matic works backwards (in comparison with a standard VCR) the supply reel is on the right hand side of the machine, and the take up reel on the left.

When trying to play a take, the machine takes on the role of tape muncher because the take up spool is not rotating, but the supply reel is running like mad.

Any ideas what might be causing this odd behaviour? and more importantly, where do I start trying to sort this mess out

As I say, FFWD and Rewind work perfectly, but play is an issue.

Cheers
Sean
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