Sony SL-F1 picture problems

[8 Tracker]

I have the portable Sony SL-F1 beta machine. When I play back recordings that it has made, there is some "tearing" of the picture, but only when there is a dark area next to a brighter one. Then the dark area is dragged over to the lighter part of the picture. When I tried recording the freeview test card to see if I could reproduce the fault it didn't happen. I am using new high-grade tape, the heads are clean and have plenty of life left in them. I am reluctant to start random tweaking, so any help or suggestions would be greatly appreciated.

[ben]

check voltages from the psu are all ok, also caps in the video processing circuitry may need changing. sorry can't be specific as don't know this unit.

[murphyv310]

Hi.
Firstly DON'T tweek, you will land up with more problems to sort out.
Can you post a photo of the fault, it's often better to see the fault than read the words.
I did loads of these in Sony, they were good but have similar stock faults to the C9.
Trevor

[8 Tracker]

Thanks gents for the quick replies. I have (hopefully) attatched some pictures. You can see that in the third picture the fault is not visible, it's only noticeable on sudden black/white changes. Hope this helps.
Mark.

[michamoo]

From my past experience of Beta machines that does look rather like a worn video head.

[VideoJunkyard]

I agree with Michamoo - worn video heads are the most likely cause - especially with machines of that age.

You stated in your first post that the heads have plenty of life left in them.... how have you checked this?

Have you tried different brands of tape? Also, do its old recordings (made when the machine was new) or pre-recorded tapes play back OK on it now?

[Michael Maurice]

I can confirm that this is indeed due to a worn head, the reason for this somewhat strange phenomenon, is that peak white represents the high frequency of the FM video modulation and as with all rec/play heads when the head wears the the high frequencies are the first to suffer.

[murphyv310]

Hi.
As with the last guys most likely the video heads, one other pointer though has any devation adjustment been tweeked or any luminance adjustment been tweeked in the record path? Anything thats maladjusted here can give the same effect.
Cheers
Trevor

[8 Tracker]

Seems pretty unanimous that the heads are to blame. Trevor - I have not owned this machine from new, so I don't know if anything has been tweaked. I haven't done anything and the machine looks "unmolested". Are there any adjustments I can make to see if the fault clears before I do a head change?
Mark.

[murphyv310]

Originally Posted by 8 Tracker

Seems pretty unanimous that the heads are to blame. Trevor - I have not owned this machine from new, so I don't know if anything has been tweaked. I haven't done anything and the machine looks "unmolested". Are there any adjustments I can make to see if the fault clears before I do a head change?
Mark.

Hi.
No, in a word unless you have a manual & test equipment leave well alone!
Get a set of heads preferably NOS Sony ones and go from there.
Good luck
Trevor

[Michael Maurice]

No Please do NOT make any adjustments. They were never easy to carry out in the first place.

The only time I ever had to adjust the carrier and deviation was after replacing an IC. That was in a C7 and it wasn't easy. It has to be right.

Both Charles Hyde and SEME show them as available but to order.

[Ian E G7OLT]

The critical question is 'How does the machine handle a known good recording?' If it plays back OK, then it's possible that the record FM deviation is over-cooked.

I remember experiencing this years ago with an SL-C7 in the early 1980s. It had been returned to our workshop for the second time in a year, for 'worn out video heads'. It was used in a duplication bank, so the running time was known - about 300 hours from memory. Fortunately the technician that got the job, after replacing the head drum, checked the old one for wear and discovered that there was still plenty of material on the head tips. This left him puzzled. Further checking revealed the FM carrier over deviation. After re-aligning, he replaced the old head drum out of curiosity, problem gone.

I guess what I'm saying is that, if you replace the head drum, the fault you're seeing will probably go away but it may well re-appear before the replacement heads are fully worn out.

As others have said, do not tweak unless you have the SONY manual, the right test equipment and are certain of what you are doing.

I still have a proper SONY Betamax alignment tape if you would like to borrow it, send me a PM with your address.

Regards,

Ian

[Michael Maurice]

I understand what you are saying Ian, but Mark has said that the machine has never been touched since new, so why would you need to reset the FM carrier and deviation?

In all cases of head wear that I've come across, both on VHS and Beta, the fault always shows up on new recordings. Playback of older recordings seemed to be fine.

Mark I reiterate:

DO NOT TOUCH THE CARRIER, DEVIATION OR RECORD CURRENT PRESETS.

[murphyv310]

Hi Michael.
Mark says in post no9 that he has not had the unit from new and does not know if its been twiddled.
I must point out that during my time with SES Glasgow (sony's affiliated service centre) every beta unit was fully set up "Prior" to condemming the heads, and there was a significant percentage that were purely out of adjustment and not needing heads.
The F1 is getting older now and if these are the original heads there is a good chance though they are sufficiently worn to give the symptoms shown. The thing is if it was my unit I would set it up first as this is the proper way of doing things. Without the gear and manual forget it, unless you can get someone to check it first.
Cheers
Trevor

[8 Tracker]

Progress:
New heads are on order.

A recording made on this machine does show the fault when played back on another. However, when a recording made on another machine is played back on the F1 I think the fault does not show. This is a difficult one to judge though, because as I said, it only happens with certain picture conditions. It did play back white credits on black background okay, something which it did not do with its' own recordings (see pics).

What test gear would I need to check (not fiddle with) the presets you talked about (apart from a service manual, which I am trying to track down)? I have scope, HF voltmeter etc.

Ian: Thanks for you offer. I'll PM you with details Monday.

[Michael Maurice]

From what I remember of servicing the C7 in the 80's, you need a frequency counter, then put in a voltage equal to sync level or black level and set the carrier to the required frequency, then adjust the input voltage to equivalent of peak white and set the deviation to that required.

Please do not quote me on this and do not try these adjustments without the correct equipment and service manual.

Hopefully once you've fitted the head all will be OK.

On the C5 C6 and C7 and some earlier models, a jig is required to adjust he centering of the head disk. I cant remember if its needed for the SLF1 but I've got it somewhere if you need to borrow it.

[murphyv310]

Hi
The F1 is more closely related to the SL-C9UB with the first of the collapseable guides and the set up is different to the earlier models.
The F1 upper drum has shims that abut on the mounting once the head is fitted careful adjustment of the shim thickness may be required, for this you need an alignment tape and scope, anyone that has done a C9 will know as its basically the same.
I would never use anything other than genuine heads though on this deck.
Trevor

[8 Tracker]

I hopefully have heads, alignment tape and service manual coming. I'll let you know how I get on in due course. Thanks to everyone for their help and loan offers.
Mark.