NV-FS200 spots on bright white scenes
 

Hello all, I have painstakingly replaced the capacitors in the PSU, TBC and Sub-Luminance / Chrominance boards but still have an issue with colour spots on some extremely bright white scenes.

I have tried playing the same tape on other machines but am not convinced that the spots are present on other machines (Mitsubishi HS-M1000 for example but only composite output, not S-Video like the FS-200 so perhaps I am not comparing apples with apples).

It is extremely hard to spot these errors on still images or even computer monitors but they are very visible when I play the mpg files back on a big screen.

Can anyone kindly shed any light on this issue ? I attach 2 stills (one from the Mitsubishi HS-M1000 (slightly dull) and one from the FS200 (brighter image) but even then, it is extremely hard to see the spots on these stills).

Perhaps in connection with this issue is that the reds are too red and there appears to be some colour bleeding / blue haze. Not sure if this is related to the same issue or a red herring. Otherwise I am very happy with the quality of this machine as you can compare from the 2 stills I attach.

I would be happy to share the video clips with anyone interested in helping.

Many thanks

Re: NV-FS200 spots on bright white scenes
 

Can I ask what TV you are using for display? It's not a CRT by any chance is it?

Re: NV-FS200 spots on bright white scenes
 

No, it is a LCD TV which is HD compatible

Re: NV-FS200 spots on bright white scenes
 

I think we need to see the video.

Re: NV-FS200 spots on bright white scenes
 

Sure, how can I share as each clip is around 100Mb ?

Re: NV-FS200 spots on bright white scenes
 

Most folks seem to use youtube to share video or you could try something like drop box.

Cheers

Mike T

Re: NV-FS200 spots on bright white scenes
 

Could be head earthing.

Re: NV-FS200 spots on bright white scenes
 

I wondered if it was "comet tails" due to that.

Re: NV-FS200 spots on bright white scenes
 

Hi all, here is a short clip of the white spots. You will have to view on a regular TV rather than through a laptop to experience the spots

Eagle eyes will need to pay attention to the bright white scenes. Feedback welcome

Edit - it seems YT have "optimised" the video so I will try another source here:

https://we.tl/t-F0tvAuV9Hu

Re: NV-FS200 spots on bright white scenes
 

I checked the head earthing and cleaned the strap but the problem persists.

I am now convinced that there is a bad cap or few caps elsewhere. Does anyone have a good understanding of the circuitry on these units and could point me in any sort of direction where to look other than the sub-boards which I already re-capped?

Could it be the head amp or main PCB ?

Re: NV-FS200 spots on bright white scenes
 

Trying to think whether the head drum or motor assembly can cause this.

Re: NV-FS200 spots on bright white scenes
 

Hi.
If this is a standard VHS machine it's pretty normal. The chrominance bandwidth is restricted on VHS and remember so is luminance, this purely down to a decrease in definition. Re the spots.... No idea unless we see a video. Post it to YouTube and put the link up here.

Re: NV-FS200 spots on bright white scenes
 

Hi, I understand but this is not happening with other players (Mitsubishi HS-M1000 for example). Maybe you missed the link but here it is:

https://we.tl/t-F0tvAuV9Hu

Re: NV-FS200 spots on bright white scenes
 

Perhaps try scrutinising the luma/ chroma/ HQ circuits again, especially if they have any of those ceramic thick-film units with surface mount electrolytics on them.

Re: NV-FS200 spots on bright white scenes
 

Thanks John, I am not familiar with the ceramic thick-film capacitors. I only replaced the electrolytic ones. What do the thick-film capacitors look like and can I test them with an ESR ?

Re: NV-FS200 spots on bright white scenes
 

Sorry, I meant the PCB modules the capacitors are physically mounted to. These mini-modules are made of a ceramic type material. The surface-mount electrolytic capacitors themselves are the silver can-type, mounted directly onto the modules.

As you can see in the attached example, the four in the middle of the photo have leaked. I'm not sure if your machine has this exact same module, or ones like it, but definitely something to look out for.

[Picture pulled from this post]

Re: NV-FS200 spots on bright white scenes
 

I can see what I think are VideoCrypt artefacts on the L & R extremities, but other than that the picture looks pretty good to me.

What you are seeing may possibly be a consequence of some "improvements" to the VHS standard collectively called "VHS HQ". If I remember correctly one of the things it did was to take liberties with the luminance level and pre/de-emphasis and although it succeeded in making the picture subjectively sharper, it seemed to me to be a bit of a fudge that would inevitably lead to compatibility issues between machines.

I would not bet money on there being an actual fault that can be fixed.

Re: NV-FS200 spots on bright white scenes
 

I have looked at the Video on the PC Monitor, and apart from the VideoCrypt could honestly not really see a issue, I would totally agree with Graham G3ZVT, it may well be a fault that's not fixable.
As you have checked the Upper drum earthing, a stab in the dark would be the the Drum Motor, but remember VHS and VHS HQ was always a compromise .
Ken G6HZG . VMARS

Re: NV-FS200 spots on bright white scenes
 

Hi.
I have to agree with Graham and Ken. I think you may be expecting more than the machine can produce. If a customer brought in a machine like that for repair if it performed well on a soak test it would be sent back NFF.
In those days spending days on a machine for an alleged fault you'd most likely get a warning of wasting company time.

I remember one customer measuring every square on the test card and if they differed by any more than 1 millimetre he would demand a new set, and then go through the same again.
Often in VCRs and TV sets of the time there were compromises made.
Splashes on screen are generally earthing or the signal level off tape being slightly low, this could be the heads themselves too, slightly low record level or even incompatibility between different machines, some of these things can be difficult to resolve and remember if there are too many drop outs due to low signal the drop out compensator will struggle.
Again in IMHO that picture looks pretty good to me.

Re: NV-FS200 spots on bright white scenes
 

Thanks both. Please note, in order to see the artefacts I am referring to, you must watch it on a TV as opposed to a monitor as these artefacts can only be seen there

Re: NV-FS200 spots on bright white scenes
 

What TV are you watching it on? If its an LCD you are wasting your time. They are poor with some VCRs, for best results use a CRT set and again not a late production set. If its OK on a monitor then its not a VCR issue, sounds like incompatibility between the VCR and the TV you are using.

I see that it's an LCD set you are using.
Remember that in the days of VHS a 33 inch set was big if you use a large LCD and of course factor in their processing it is more than likely you'll see an issue that won't show on a CRT set

Re: NV-FS200 spots on bright white scenes
 

Thanks Trevor. I am watching the digital file on an LCD TV, as opposed to plugging the VCR directly into the TV. I am playing the file on a linux set top box connected to the TV via HDMI and the artefacts are as clear as day.

I would expect that the file is a carbon copy of the VHS especially as I am using a time base corrector to capture these tapes

Re: NV-FS200 spots on bright white scenes
 

I notice that on my video scope much of the bright white background is clipped/crushed, even if much of the time the video level is under 100% modulation. Occasionally the level extends above the 100%. Is that where the dots appear?

I agree with others here that we must have realistic expectations of VHS performance.

Also when capturing as well as in post, attend to contrast levels. It's better to have a little lower contrast at capture if it means avoiding loss of highlight detail as well as shadow detail. At the capture stage we dont go for the final "look". The time for that is in post. Instead just try to capture all the information from the tape without loss, without distortion.

Re: NV-FS200 spots on bright white scenes
 

The digital file is likely encoded lossily so not a carbon copy. Realistically, there could still be a fault, but the signal is mangled and degraded so many times between the recording and your eye, it would be really hard to tell the exact cause. Ideally, you should test the set using a factory test tape and viewing it on measuring equipment or at least a CRT TV set. 50Hz with analog signal processing and a good sharp tube.

Re: NV-FS200 spots on bright white scenes
 

When you think of it a VCR is analogue and should be viewed on an analogue CRT TV or suitable analogue CRT monitor. Digital can and does make things look...... Well not so good. I had a Panasonic NV20?? (too long ago to remember model numbers and fixed too many) and a Grundig 25 inch, the results were excellent, a few years later it was connected to an early LCD it looked terrible.

Re: NV-FS200 spots on bright white scenes
 

I believe the main problem for presentation today is not that the VCR is analog but that the signal is "interlaced" as was the entire television system back then and the system worked fine. To play interlaced on a "progressive" system is problematic and involves fudges because the two systems are incompatible.

Re: NV-FS200 spots on bright white scenes
 

Certainly try this machine on a CRT TV and if same , then I think as before, head or drum assembly.

Re: NV-FS200 spots on bright white scenes
 

Thanks all for your inputs. I have been experimenting with different workflows and removed the external Time Base Corrector then tried a capture and it seems the spots are very much minimised so perhaps the spots are being exaggerated by the Time Base Corrector. Does anyone know if this is feasible?

Re: NV-FS200 spots on bright white scenes
 

The DOC in the Timebase Corrector may well be accentuating the perceived problem.

David.

Re: NV-FS200 spots on bright white scenes
 

I thought a DOC could only operate with access to the RF signal.

Re: NV-FS200 spots on bright white scenes
 

I think I now have a different fault with this player. It was playing fine up until today then I suddenly saw all these lines across the screen. Any help appreciated

https://we.tl/t-aTgMN1bsfK