Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White - UK Vintage Radio Repair and Restoration Discussion Forum

Henenen · 24th Oct 2017, 11:37 am

I have a Panasonic NV-FS88 which seems to be working fine other than it will randomly swap between Colour and Black & White output for several minutes at a time during playback.

Is this an easy fix?

I've tried different scart cables, get same fault so I know it's not that.

Vintage Engr · 24th Oct 2017, 12:04 pm

I assume that the monochrome playback is clean? If it isn't it might be worth doing a head/tape path clean.

Do you have a service manual for this?

If you do, it might be worth checking the power rail around the video processing areas. Many Panasonic & other makes of VCR's etc from this period suffer from failiure of small electrolytic capacitors, going high ESR.

Looking at the relevant power rails with an oscilloscope usually reveals lack of decoupling, so the chroma signal gets lost to the power supply.
There could of course be many other reasons, so a manual is really a necessity.

David.

HamishBoxer · 24th Oct 2017, 1:30 pm

Always check/change secondary psu caps for oddball faults before moving on.I have had a few on NatPan.

Henenen · 24th Oct 2017, 2:53 pm

The playback in B&W is clean, yes, and the tape path has been cleaned.

I don't have a service manual though. Was hoping it was a simple/common problem.

John123 · 24th Oct 2017, 7:18 pm

Most likely to be a capacitor issue which tends to plague this generation of machines as they're quite long in the tooth, by now. Usually most of the trouble is with the S-VHS side of things.

Try leaving a tape to play from start to finish as it might need a little 'waking up' especially if it hasn't been used in a good while. Also, check the 'Normal/ S-Video Out' switch on the back is not stuck half way or anything. It should be set to 'Normal' unless you are using S-Video over SCART.

Henenen · 25th Oct 2017, 12:27 pm

Funnily enough, John123, I ran it all day yesterday, and this morning, and it has actually been fine.

Up until that point it hadn't been used for years, so maybe the capacitors did just need 'warming up'.

Welsh Anorak · 25th Oct 2017, 3:39 pm

Hi
I think you're right - the SMD electrolytics used in this machine are notorious, and not an easy fix. Keep it warm and dry and hopefully the fault won't come back.
Glyn

John123 · 25th Oct 2017, 6:29 pm

Sounds like it just needed some encouragement! Yes it's not uncommon for old capacitors to need a little time to 're-form'. As above, look after it and it should be OK for now.

Vintage Engr · 25th Oct 2017, 7:26 pm

Yes, these capacitors tend to work again when gently warmed up.
Believe it or not, the same series of SMD caps were used in both domestic & broadcast equipment.

I have a drawer full of 'new' ones, I sometimes changed up to 40 on one single board. Not a nice job, but it generally did the trick.

David.

24th Oct 2017, 11:37 am	#1
Henenen Tetrode Join Date: Mar 2011 Location: London, UK. Posts: 81	Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White I have a Panasonic NV-FS88 which seems to be working fine other than it will randomly swap between Colour and Black & White output for several minutes at a time during playback. Is this an easy fix? I've tried different scart cables, get same fault so I know it's not that.

24th Oct 2017, 12:04 pm	#2
Vintage Engr Heptode Join Date: Jan 2008 Location: Shrewsbury, Shropshire, UK. Posts: 841	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White I assume that the monochrome playback is clean? If it isn't it might be worth doing a head/tape path clean. Do you have a service manual for this? If you do, it might be worth checking the power rail around the video processing areas. Many Panasonic & other makes of VCR's etc from this period suffer from failiure of small electrolytic capacitors, going high ESR. Looking at the relevant power rails with an oscilloscope usually reveals lack of decoupling, so the chroma signal gets lost to the power supply. There could of course be many other reasons, so a manual is really a necessity. David.

24th Oct 2017, 1:30 pm	#3
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White Always check/change secondary psu caps for oddball faults before moving on.I have had a few on NatPan. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

24th Oct 2017, 2:53 pm	#4
Henenen Tetrode Join Date: Mar 2011 Location: London, UK. Posts: 81	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White The playback in B&W is clean, yes, and the tape path has been cleaned. I don't have a service manual though. Was hoping it was a simple/common problem.

24th Oct 2017, 7:18 pm	#5
John123 Heptode Join Date: Jan 2007 Location: Luton, Bedfordshire, UK. Posts: 891	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White Most likely to be a capacitor issue which tends to plague this generation of machines as they're quite long in the tooth, by now. Usually most of the trouble is with the S-VHS side of things. Try leaving a tape to play from start to finish as it might need a little 'waking up' especially if it hasn't been used in a good while. Also, check the 'Normal/ S-Video Out' switch on the back is not stuck half way or anything. It should be set to 'Normal' unless you are using S-Video over SCART. __________________ Regards, John

25th Oct 2017, 12:27 pm	#6
Henenen Tetrode Join Date: Mar 2011 Location: London, UK. Posts: 81	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White Funnily enough, John123, I ran it all day yesterday, and this morning, and it has actually been fine. Up until that point it hadn't been used for years, so maybe the capacitors did just need 'warming up'.

25th Oct 2017, 3:39 pm	#7
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,918	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White Hi I think you're right - the SMD electrolytics used in this machine are notorious, and not an easy fix. Keep it warm and dry and hopefully the fault won't come back. Glyn

25th Oct 2017, 6:29 pm	#8
John123 Heptode Join Date: Jan 2007 Location: Luton, Bedfordshire, UK. Posts: 891	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White Sounds like it just needed some encouragement! Yes it's not uncommon for old capacitors to need a little time to 're-form'. As above, look after it and it should be OK for now. __________________ Regards, John

25th Oct 2017, 7:26 pm	#9
Vintage Engr Heptode Join Date: Jan 2008 Location: Shrewsbury, Shropshire, UK. Posts: 841	Re: Panasonic NV-FS88 Super VHS VCR - Flicks between Colour / Black & White Yes, these capacitors tend to work again when gently warmed up. Believe it or not, the same series of SMD caps were used in both domestic & broadcast equipment. I have a drawer full of 'new' ones, I sometimes changed up to 40 on one single board. Not a nice job, but it generally did the trick. David.