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Old 28th Feb 2021, 1:53 pm   #21
Snarf81
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Default Re: Sanyo VTC5150 fault.

The heads on the vcr seem to be in very good condition. I've looked closely at them through a good zoom lens and they don't appear to be worn or damaged etc. No telltale signs of head wear on the picture (when it's locked in).

I do have a spare reel motor, so I'll change it later today and see what happens. I don't have a bench PSU, so I can't increase voltage on it unfortunately. Would a failing reel motor cause the vcr tracking not to work? I thought it just drove the take-up spool on playback. Very odd.

Thanks for the suggestions!!

Last edited by Snarf81; 28th Feb 2021 at 1:55 pm. Reason: Info added.
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Old 28th Feb 2021, 3:07 pm   #22
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Default Re: Sanyo VTC5150 fault.

As far as I know, a failing reel motor would exacerbate drop-out, but not sure about making tracking adjustment inoperative.

Philip
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Old 28th Feb 2021, 3:34 pm   #23
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Default Re: Sanyo VTC5150 fault.

I was thinking that too. I have another Sanyo model (vtc6500) that had reel motor trouble, but that just had a flat spot in the motor and the tracking worked on that. Hmm
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Old 28th Feb 2021, 7:08 pm   #24
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Default Re: Sanyo VTC5150 fault.

So I changed the reel motor and the problem is still there. I have found that I do need to get hold of a replacement top geared idler as mine is making a groaning noise and sometimes a chattering sound.
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Old 1st Mar 2021, 4:37 pm   #25
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Default Re: Sanyo VTC5150 fault.

Have you tried the motor torque modification by changing the value of a diode and a resistor in the syscon board? I did that on my VTC 5000 and 5550 and it improved take-up torque but I don't know if it's applicable to the 5150.
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Old 3rd Mar 2021, 6:19 pm   #26
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Default Re: Sanyo VTC5150 fault.

I've not fitted that yet, but I've got the kit coming in the post sometime this week hopefully, including a complete idler assembly. I doubt it'll cure the servo fault, but the top idler needs to be replaced in any case.
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Old 3rd Mar 2021, 9:20 pm   #27
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Default Re: Sanyo VTC5150 fault.

I’d appreciate knowing where you’re getting the idler assembly from, if it’s a new replacement...

Philip
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Old 3rd Mar 2021, 9:29 pm   #28
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Default Re: Sanyo VTC5150 fault.

Philip, the idler assembly is indeed new, well, new old stock. Take a look at the last email I sent you and it tells you where I'm getting my assembly from, but I'm told it's the last one in stock unfortunately.

Rich.
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Old 5th Mar 2021, 1:05 pm   #29
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Default Re: Sanyo VTC5150 fault.

The new bits arrived, I've installed the torque modification, top idler and another new idler belt, but still the same problem *bangs head on floor*

It looks like I will have to re cap the servo board and see if that cures it.

Rich.
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Old 5th Mar 2021, 2:16 pm   #30
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Default Re: Sanyo VTC5150 fault.

I've just uploaded a short video of the fault to YouTube.

It might appear that the tracking control works when I turn it, but it's just the picture settling down after its rolling behaviour.

https://youtu.be/G0_VzZkTneY
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Old 5th Mar 2021, 5:32 pm   #31
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Default Re: Sanyo VTC5150 fault.

Rich.

Looking at your youtube video, it's obvious that the capstan motor isn't locking into the right speed. Since you get a stable still picture in pause, the drum servo should be OK. In forward and reverse picture search you should get 3 or 4 steady noise bars and not rolling noise bars like you do now. There are different adjustments for the capstan free run speed for each mode (play, forward search, and reverse search). If neither of those make any difference when you adjust them, I would suspect bad electrolytics in the servo board or missing control track pulses. Unlike Sony machines and older Sanyo machines, these particular Sanyo ones don't mute the video and audio when the control track is missing.

Fivos
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Old 6th Mar 2021, 7:27 am   #32
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Default Re: Sanyo VTC5150 fault.

Your head switching point is way out. It is supposed to be 6.5 lines from the bottom of the picture.

The magnets that tell the servo where the head is scanning with respect to the tape, are in the wrong position. Fix that to start with for the tracking.

The A.C.E. head/alignment might also need a look.

Wayne.
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Old 6th Mar 2021, 11:13 am   #33
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Default Re: Sanyo VTC5150 fault.

Thanks for the replies!

Wayne, how do I fix the magnets please?
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Old 6th Mar 2021, 12:20 pm   #34
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Default Re: Sanyo VTC5150 fault.

Quote:
Originally Posted by Snarf81 View Post
The new bits arrived, I've installed the torque modification, top idler and another new idler belt, but still the same problem *bangs head on floor*

It looks like I will have to re cap the servo board and see if that cures it.

Rich.
I wouldn't have expected reel-drive problems to have affected tracking - So suggestions I'd made were just about intermittent shut-down / loop of tape being left out (often a bit of design fault with these, with reel-fault shut-off ).
If you haven't got a variable-voltage bench PSU, then could always improvise a bit with a high power series variable resistor (Rheostat) or taps from a few in-series AA batteries, to get 1.5V steps.
You can also make a simple LM317 etc. adjustable regular circuit with the IC and a preset / resistors, or use a PC Fan-speed controller module, fed from 12V which is essentially one of these (but might only adjust down to about 7V). There's also many adjustable switch-mode modules for < £2 from China on the usual online auction websites etc. that can be used to generate a varety of voltages.

With regards to tracking problems, are these playback of tapes recorded on another machine (that could have been a bit off) or playback of its own recordings? (which should playback with tracking in centre, if no other fault).

If there's an issue with pulses from the Audio/ Control Head assembly, or capstan motor speed / phase control, then you will probably get slow constant cycling of noise bar position, as the control loop hunts and can't lock. Whereas stationary noise bars indicate a tracking or tape-path alignment issue.

Incorrectly adjusted / worn tape guides / pinch roller can also be cause of noise bars at to / bottom of picture.

Have you inspected the tape in the cassette to see if the top / bottom edges are undamaged / if they are getting damaged after being played in the VCR?

Last edited by ortek_service; 6th Mar 2021 at 12:27 pm.
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Old 6th Mar 2021, 3:23 pm   #35
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Default Re: Sanyo VTC5150 fault.

Wayne

Are you reffering to the monoscope pattern in post #14? If so, the head switching point in the monoscope pattern of the alignment is placed in the middle of the screen for a reason. And that is for performing dihedral adjustment on the video heads.

Fivos
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Old 7th Mar 2021, 9:07 am   #36
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Default Re: Sanyo VTC5150 fault.

Yes Fivos.
On some machines the magnet, or magnets, were on a part of the head drum assembly that could be attached to the assembly in the wrong position. All sorts of faulty installation/alignment were possible.

After looking at the service manual, I see the magnets are part of the head disc and can not be out of adjustment.

Best of luck.

Wayne.
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Old 10th Mar 2021, 10:43 am   #37
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Default Re: Sanyo VTC5150 fault.

Wayne

You are right. The PG magnet(s) is/are mounted on the head disc. I have a Sanyo Beta and a Sony Beta head disc and both have a single PG magnet permanently attached onto the disc. I think if you install the head disc backwards, you will have a picture but it will be in black and white. Correct me if I'm wrong on that.

Fivos
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Old 12th Mar 2021, 8:39 am   #38
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Default Re: Sanyo VTC5150 fault.

Hello All.
Regarding the Sanyo VTC-5150.

That model was never released here in Australia. It does however appear to be an improved version of the VTC-5000, VTC-5000Mk2.

From what I can deduce from the thirty-seven posts, pictures, and schematics, and a video, is that the machine in question has a number of problems. The machine now appears to be almost working properly, with what looks to be some servo issues.

There is no use in attempting to adjust the servos if the deck is not working properly. Let's face it, the machine is thirty-eight years old. We must first repair the deck. Clean and lubricate bearings where required, check moving arms for freeness of operation. Belts for being too loose, or replacements for being too tight. (common with generic belt kits)
Stiction of the tape. Stiction of the tape ruler and upper-drum. Of the tape itself, (needs cooking)
Mouldy tapes? Motor bearings. Do they spin freely? The brake band. Was the felt given a clean with a tooth brush to remove felt dust? All the guides and surfaces that the tape passes over.
Since we are dealing with servo issues? How about the pinch roller. Often these can cause the tape to wander away from the control head. You can't always see the distortion of the pinch roller. Sometimes it will be made to show itself in trick modes like cue, of review.

End of part one. Don't give up. From the video I saw, this machine can produce a good picture.

Wayne.
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Old 14th Mar 2021, 5:58 am   #39
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Default Re: Sanyo VTC5150 fault.

Part two.

Once the mechanism has been serviced/repaired, then it is time to adjust the servo controls.
I use a prerecorded tape for playback related adjustments. Remember that the F.M. signal from a bought movie will be about half the level that of a recording made on a VCR. It would be helpful if the control track pulses could be viewed on an Oscilloscope to prove their presence, and amplitude.

It did appear that in the beginning, there were numerous issues with this machine. Most seem to have been fixed during the process of fixing the machine. Now it looks to be only the servo needs adjusting? But I am not sure. The servos look too damn close to correct, to be the problem!
Does the tape travel smoothly across the mechanism? No momentary pauses? No wild fluctuations of the back-tension arm ?

Rich. Keep us all informed as to your progress.

Meanwhile I will go back to the three machines I am working on, that could be classed as “Complete *******s.”
No, or very poor manuals, unobtainable parts, obtainable parts expensive, conductive boards due to leaking back-up battery, leaking caps. Still. It's my own fault. I like to work on the rarer, more obscure machines.

Wayne.
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Old 15th Mar 2021, 3:33 pm   #40
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Default Re: Sanyo VTC5150 fault.

Thanks for the replies and suggestions. It's appreciated.
I've not been too well the past week so my repairs are on hold til I'm feeling more myself.
I'll let you know what I find.

Thanks all

Rich.
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