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Old 23rd Feb 2021, 2:00 pm   #1
Snarf81
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Default Sanyo VTC5150 fault.

Hi all,

I've just gotten hold of a Sanyo vtc5150, and after replacing the usual idlers and belts I've found a problem with it.

It laces and unlaces the tape fine when play or pause is pressed but when I press any transport button e.g rewind, it'll rewind for approx 3 seconds then stop and lace up the tape. I then have to press stop to unlace it back into the cassette (sometimes the take up reel doesn't wind the tape back into the cassette). It's the same with play mode, ffw etc. If I press pause the tape is laced around the head as normal and then I press play, I can cue and review for a few seconds until it stops dead. Then I have to press stop to get it to unlace.

I've never seen this fault with a Sanyo before and any help and suggestions would be very appreciated.

Many thanks

Rich.
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Old 23rd Feb 2021, 2:09 pm   #2
Welsh Anorak
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Default Re: Sanyo VTC5150 fault.

Ages since I've seen one of these, but we used to have lots of trouble with intermittent reel motors. Worth a look?
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Old 23rd Feb 2021, 2:31 pm   #3
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Default Re: Sanyo VTC5150 fault.

Rich, is the replacement idler new or used? If used, the rubber tyre may be past it’s best, which would account for poor/stalling FFWD and REW. A sticky tape can also cause this as I’ve had the same problem with 5150’s.

The best guy for Beta issues on here is Sanbeta (the great Kevin Lambert).

Philip

Last edited by The_Archiver; 23rd Feb 2021 at 3:01 pm.
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Old 23rd Feb 2021, 2:45 pm   #4
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Default Re: Sanyo VTC5150 fault.

Thanks for the replies.

I replaced the lower idler for a new unused one. There's lots of torque on the supply and take up reels. Whilst I had the idlers off I put a few drops of oil on the reel motor spindle shaft bearing (I lifted the plastic dust cover ring on the motor spindle to do this).

I meant that when rew or ffw is pressed it'll do that for 3 seconds then stop and lace the tape up. I then have to press stop to get it to unlace. I'm aware of how these are only laced in play, rec, pause etc. I've thoughrougly cleaned all of the tape path and videohead, and tried different videocassettes, but it's still the same. Whilst in Play-Pause mode I've got a good picture, and picture search forward and back the picture is stable (for the few seconds at least haha)

Reel motor fault? Hmmm. It seems to spin freely enough without the belt on the pulley without any flat spots, so to speak.

Thanks for the suggestions!

Rich.

Last edited by Snarf81; 23rd Feb 2021 at 2:47 pm. Reason: More info added.
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Old 23rd Feb 2021, 5:46 pm   #5
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Default Re: Sanyo VTC5150 fault.

Hi Rich. There is a known syscon bug with the VTC 5000 and early 5150s where the machine laces up in case of reel drive failure, instead of going into stop mode. If the tape is running properly when you press REW but the machine laces up and shuts down, there might be a bad reel rotation sensor. A good way to check that is to see if the tape counter on the VFD display is moving during any tape transport function.

Fivos
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Old 23rd Feb 2021, 6:16 pm   #6
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Default Re: Sanyo VTC5150 fault.

Cheers Fivos!

I'll have a look at the counter display a little later. If the sensor is defective, do you know anywhere I could get one from please?

Rich
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Old 23rd Feb 2021, 6:35 pm   #7
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Default Re: Sanyo VTC5150 fault.

Rich

The reel rotation sensor in these machines is optical (LED and phototransistor). So it could just be dirt build-up on the sensor. If I remember correctly, the take-up hub has slots on the bottom of it that pass through the sensor to create on-off pulses to signal the syscon circuit so that it knows whether the reel is rotating or not. To access and clean the sensor you will have to remove the take-up spool/hub which is held in place by a plastic cut-washer. Be careful not to lose the other washers and spacers.

Regards

Fivos
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Old 23rd Feb 2021, 8:16 pm   #8
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Default Re: Sanyo VTC5150 fault.

I've looked at the counter display and it's not running either backwards or forwards, just staying on all the zero's.

I took the take up reel off and cleaned the sensor, it glows a dim red when the vcr is powered up. It's certainly not bright (if it's meant to be bright?)

Last edited by Snarf81; 23rd Feb 2021 at 8:18 pm. Reason: Info
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Old 23rd Feb 2021, 9:37 pm   #9
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Default Re: Sanyo VTC5150 fault.

Errrm,
That fault suddenly disappeared! It's now playing and doing everything it should, but the capstan speed seems to be a touch too fast so I'm not getting a stable picture, just some rolling.

Is there a capstan speed adjustment pot on these?
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Old 24th Feb 2021, 9:37 am   #10
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Default Re: Sanyo VTC5150 fault.

Having had the same issue on a 5150 in the past, it’s one of the 10 VR’s on board SV-1 [to the immediate right of the cassette carriage], but can’t remember which.

Relevant photos from Service Manual attached which you may find useful.

Philip
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Old 24th Feb 2021, 2:49 pm   #11
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Default Re: Sanyo VTC5150 fault.

Rich

Yes there should be a dim red LED shining underneath the take-up spool so what you see is normal. As for the capstan servo problem, see post #10.
PS: the service manual is likely a bit wrong. You should use a multimeter or voltmeter to measure the voltage on TP4004 while adjusting VR4010, not an oscilloscope.

Fivos
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Old 24th Feb 2021, 3:01 pm   #12
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Default Re: Sanyo VTC5150 fault.

Thanks for the replies!
I set the capstan speed using an alignment tape colour bars with the 3k tone and having the 3k tone playing from my phone. I've got it near enough spot on now. It must have drifted a bit over the years. I've included a picture of the pots marked in their original position and you'll notice VR10 had to be turned down a bit.

The problem with it now is that the tracking control does nothing.

Ah, the joys of Beta
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Old 24th Feb 2021, 3:35 pm   #13
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Default Re: Sanyo VTC5150 fault.

Oh. An alignment tape! That's a very useful and rare tool. Play back the monoscope pattern section of the tape and see if the lines below the head switching point are not splitting apart. If they do, you may have to center the tracking control or perform the video head dihedral adjustment (very unlikely and not sure if it's possible on Sanyos). Do you get a wow & flutter effect when you turn the tracking knob while playing back the 3KHz tone?
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Old 24th Feb 2021, 3:52 pm   #14
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Default Re: Sanyo VTC5150 fault.

I don't get any effect at all from the tracking control.

I just put the multimeter on the test point and to get the required voltage the speed is running too fast.
I put the alignment tape back in and set it back to the 3k tone and that takes the multimeter readings jumping up to 7v and then whilst at the speed on the alignment tape and phone 3k tone, the voltage jumps from 2v to 7v. It's not stable.

On its own recordings the picture rolls every 3 seconds.
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Old 24th Feb 2021, 4:29 pm   #15
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Default Re: Sanyo VTC5150 fault.

If you can't get the capstan motor to lock into the correct speed even by adjusting VR10, make sure the audio/control track head is clean and the tape is properly contacting the head. Also check for loose connections and broken solder joints on the servo board. At last, some of the 38-year-old capacitors could also be dry or high ESR. An unusual fault could be related to the tracking control potentiometer itself. The resistance of the pot should rise and drop evenly when you adjust it. I remember when my VTC 5350 couldn't lock into the correct speed because the wires connecting the tracking knob to the servo board had become disconnected by accident.

Fivos
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Old 24th Feb 2021, 4:57 pm   #16
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Default Re: Sanyo VTC5150 fault.

I've turned it off for the rest of the day as I've got annoyed with it haha.
I'll look again tomorrow and see if all the wires on the tracking control are attached properly.

Thanks for the replies and suggestions, I'll report back tomorrow afternoon.
Rich.
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Old 27th Feb 2021, 10:08 am   #17
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Default Re: Sanyo VTC5150 fault.

Well this has me stumped!
No wires are off the tracking pot, the audio control head is as clean as a whistle, I've checked for loose connections etc and can't find any. Darn this old Sanyo!
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Old 27th Feb 2021, 12:18 pm   #18
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Default Re: Sanyo VTC5150 fault.

I forgot to mention that the voltage at centre tracking is 2.80v, it does rise and drop when the knob is turned from one end to the other.
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Old 27th Feb 2021, 8:00 pm   #19
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Default Re: Sanyo VTC5150 fault.

There is always the possibility that the video heads are too worn, as happened to one of my 5150’s last year when tracking adjustment ended up being unable to produce a stable picture. History and known amount of prior usage of the machine may tell...

Philip
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Old 28th Feb 2021, 12:07 pm   #20
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Default Re: Sanyo VTC5150 fault.

I found the Sanyo VTC5xxx heads seem to last a very long time - never had to replace any - as Rew/FF was done with the tape fully-unlaced - like early VHS, instead of the Sony approach of doing it against the heads.

This may also help in not causing the heads to clog-up (although also harder to clean them, with tape action, once clogged).
I used to find that Sanyo / Sony tape used to be much more problematic for shedding bits from the tapes, compared to BASF Cr02 ones.
However, since all Betamax tapes are now rather old, they could all be degrading and prone to clogging heads (as old Floppy disks now seem to)


I also recall many problems with intermittent tape-chewing due to the stop on fault, with tape laced-up design issue, rather than trying to wind it back in.
And despite doing some of the recommended modes / changing Idler / tyres / trying to modify clutch-surface on these, it seems the fairly basic DC reel motor was responsible for much of this, due to flat spots. I seem to recall that you could tell, by connecting to a variable bench PSU, and slowly increasing the voltage from 0V. A good motor should with no load on it, should start turning slowly, without stopping, at about 2V.
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