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

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Old 17th Nov 2018, 6:36 am   #1
poya688
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Post The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

hello

The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80.
https://www.dropbox.com/s/izkpscpzh0...video.mp4?dl=0
please help me

thank you
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Old 17th Nov 2018, 12:06 pm   #2
simpsons
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

Good morning QOM

The video shows a "as new" condition machine and I assume the following should not apply but this where I would start

First the pinch roller. Should it have become concave, then the tape will be pulled toward the upper and lower rubber roller cyclically.

Next, check for oxide contamination on the capstan. The tape will not be in close contact with the pinch roller along its full length if contaminated and so pulling the tape towards the contaminated area.

But, given the machine looks so "new," then back tension or take up spool torque could be an issue. Loking at how the tape jumps suggests this is a possibility.

I am not sure how the brake is applied on your machine for back tension but in both instances, the reels can be tricked to make the tape free of tension.

Hope this helps

Chris
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Old 17th Nov 2018, 11:12 pm   #3
poya688
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Post Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

hello

I did what I said
I checked the pinch roller and had no problem. I also cleaned the capstan
May I ask you to guide how to set tension and whether the problem is the same?
Thanks for helping me to come to a complete conclusion.

Thankful
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Old 18th Nov 2018, 6:55 pm   #4
poya688
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

hi
please help me.
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Old 18th Nov 2018, 8:47 pm   #5
simpsons
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

Download from electrotanya the Samsung SV 671 Service Manual. You will see the manual details by looking at Images after Googling the model number. The chassis looks the same as used on your A80 and the manual includes a brief description of the chassis, fault conditions and adjustment.

Unless your machine has been "got at" look for the obvious because most adjustments are factory set and do not require correction and you will require use of an oscilloscope together with an alignment tape to do most things. Whilst you could mke your own alignment tape from a known good machine, if you don't have a scope, you can't easily make adjustments.

Last. Video tape is very thin. Be careful.

Good luck.

Chris
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Old 25th Nov 2018, 12:36 am   #6
poya688
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

Hello to friends

I did not see a problem with the oscilloscope, but in the part that appears inside the figure, the bar from the gap that should be inserted is higher than the friend's guide, which problem?

https://www.dropbox.com/s/atl6moelgv...pp_LI.jpg?dl=0

thank you
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Old 25th Nov 2018, 1:25 am   #7
ben
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

After seeing video in 1st post. Looks like the take up torque is far too high. I'd check /replace the clutch.

A pinch roller would have to be in really bad shape (rock hard, for example) to cause that amount of tape damage IMHO.
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Old 25th Nov 2018, 7:40 pm   #8
simpsons
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

I think Ben has come to the same conclusion as myself.

The FM envelope you say is OK. This means that tape alignment is correct and importantly the back tension and or lower video drum wear is within spec.

Check out the tape take up spool torque by googling "Practical VCR Repair supply and take up" then opening post "page 192 - Google Books Result."

Follow the suggestion on using a screwdriver to check for excessive torque, include disengaging the pinch roller using pause and note any change in the fault condition when play is again initiated.

The Service Manual spec is 42g/cm on playback which is not a lot. The manual though doesn't show how the drive belt, spring and clutch/brake work and so you will need to visually note contamination etc on the friction slip ring, often a felt disk.

You're a little too far away for a BVWS Member to pop over and help out!

Chris

Last edited by simpsons; 25th Nov 2018 at 7:41 pm. Reason: detail
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Old 6th Dec 2018, 5:37 pm   #9
poya688
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

hello

A friend can give me a free download of this book (Practical VCR Repair Supply and Take Up)? So I can study and I can use it because I could not find the free version

Thanks
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Old 6th Dec 2018, 6:34 pm   #10
simpsons
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Default Re: The up and down bar on the ctl and pinch roller in the Samsung video model sv-a80

Hello again

Just in case I was too free in my description for the Google search.

Google Search only for - Practical VCR Repair supply and take up.

Scroll down until you see - PRACTICAL VCR REPAIR - page 192 - Google books result.

Do not search the whole text ""Practical VCR Repair supply and take up" then opening post "page 192 - Google Books Result."

I am sorry if I have made life difficult for you.

Chris
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