Jitter on locked horizontal part of image - B&W transistorized TEC monitor

[John Robertson]

I have an older monitor from a video game - and it has a jitter on the
horizontal lines on the screen (vertical is locked), yet I don't see
this jitter on the H Sync. Using a signal generator (Cross-Hatch, Dot,
etc.) and all outputs are the same. Game source also shows same jitter
on same screen.

It is not the WICO monitor signal generator as other B&W monitors show a
locked image.

Schematics here:

http://www.flippers.com/pdfs/TEC_TM-600_TM-623_Monitor.pdf

Monitor has been recapped. Horizontal does lock, but jitter still present.

Suggestions appreciated!

Thanks,

John :-#)#

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[Sjouke Burry]

On 26.02.17 23:06, John Robertson wrote:
> I have an older monitor from a video game - and it has a jitter on the
> horizontal lines on the screen (vertical is locked), yet I don't see
> this jitter on the H Sync. Using a signal generator (Cross-Hatch, Dot,
> etc.) and all outputs are the same. Game source also shows same jitter
> on same screen.
>
> It is not the WICO monitor signal generator as other B&W monitors show a
> locked image.
>
> Schematics here:
>
> http://www.flippers.com/pdfs/TEC_TM-600_TM-623_Monitor.pdf
>
> Monitor has been recapped. Horizontal does lock, but jitter still present.
>
> Suggestions appreciated!
>
> Thanks,
>
> John :-#)#
>

Sounds like the power supply is starting to fail.
Check the caps there, for bulging ca[p tops, and replace them.
While it is open, also check around the high voltage area,
and if you smell ozone, something is producing sparks.
Clean and replace bad caps.

[ohg...@gmail.com]

You said it "has a jitter on the horizontal lines on the screen (vertical is locked)". Just want to be clear. Do you mean to say the horizontal lines from the generator are jittering up and down indicating a vertical problem?

[John Robertson]

On 2017/02/26 4:38 PM, ohg...@gmail.com wrote:
> On Sunday, February 26, 2017 at 5:06:38 PM UTC-5, John Robertson wrote:
>> I have an older monitor from a video game - and it has a jitter on the
>> horizontal lines on the screen (vertical is locked), yet I don't see
>> this jitter on the H Sync. Using a signal generator (Cross-Hatch, Dot,
>> etc.) and all outputs are the same. Game source also shows same jitter
>> on same screen.
>>
>> It is not the WICO monitor signal generator as other B&W monitors show a
>> locked image.
>>
>> Schematics here:
>>
>> http://www.flippers.com/pdfs/TEC_TM-600_TM-623_Monitor.pdf
>>
>> Monitor has been recapped. Horizontal does lock, but jitter still present.
>>
>> Suggestions appreciated!
>>
>> Thanks,
>>
>> John :-#)#
>

> You said it "has a jitter on the horizontal lines on the screen (vertical is locked)". Just want to be clear. Do you mean to say the horizontal lines from the generator are jittering up and down indicating a vertical problem?
>

The monitor has had all electrolytic capacitors replaced, along with
most of the mylar ones.

We use Panasonic caps for electrolytics.

No, the lines are jittering sideways - indicating a horizontal problem.
If I adjust the horizontal control the jittering stays much the same as
the picture shifts sideways until it loses the lock.

John :-#(#

[ohg...@gmail.com]

On Monday, February 27, 2017 at 12:44:01 AM UTC-5, John Robertson wrote:
> On 2017/02/26 4:38 PM, ohg...@gmail.com wrote:
> > On Sunday, February 26, 2017 at 5:06:38 PM UTC-5, John Robertson wrote:
> >> I have an older monitor from a video game - and it has a jitter on the
> >> horizontal lines on the screen (vertical is locked), yet I don't see
> >> this jitter on the H Sync. Using a signal generator (Cross-Hatch, Dot,
> >> etc.) and all outputs are the same. Game source also shows same jitter
> >> on same screen.
> >>
> >> It is not the WICO monitor signal generator as other B&W monitors show a
> >> locked image.
> >>
> >> Schematics here:
> >>
> >> http://www.flippers.com/pdfs/TEC_TM-600_TM-623_Monitor.pdf
> >>
> >> Monitor has been recapped. Horizontal does lock, but jitter still present.
> >>
> >> Suggestions appreciated!
> >>
> >> Thanks,
> >>
> >> John :-#)#
> >
> > You said it "has a jitter on the horizontal lines on the screen (vertical is locked)". Just want to be clear. Do you mean to say the horizontal lines from the generator are jittering up and down indicating a vertical problem?
> >
>
> The monitor has had all electrolytic capacitors replaced, along with
> most of the mylar ones.
>
> We use Panasonic caps for electrolytics.
>
> No, the lines are jittering sideways - indicating a horizontal problem.
> If I adjust the horizontal control the jittering stays much the same as
> the picture shifts sideways until it loses the lock.
>
> John :-#(#

I wonder if you're describing what we used to call "piecrusting". Most of that was was from leaking HV. Remove the HV rectifier and see if there's any green schmutz in the contacts. Any corrosion will cause arcing.

[Chuck]

On Sun, 26 Feb 2017 14:06:31 -0800, John Robertson <sp...@flippers.com>
wrote:

>I have an older monitor from a video game - and it has a jitter on the
>horizontal lines on the screen (vertical is locked), yet I don't see
>this jitter on the H Sync. Using a signal generator (Cross-Hatch, Dot,
>etc.) and all outputs are the same. Game source also shows same jitter
>on same screen.
>
>It is not the WICO monitor signal generator as other B&W monitors show a
>locked image.
>
>Schematics here:
>
>http://www.flippers.com/pdfs/TEC_TM-600_TM-623_Monitor.pdf
>
>Monitor has been recapped. Horizontal does lock, but jitter still present.
>
>Suggestions appreciated!
>
>Thanks,
>
>John :-#)#

If the problem isn't HV arcing, check or replace parts from pin3 of
the flyback including the 2 AFC diodes D401 and 402. The diodes on
this line I'd just replace.

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[Benderthe.evilrobot]

"Chuck" <ch...@mydeja.net> wrote in message
news:lhm8bcdtqcafq50bk...@4ax.com...

> On Sun, 26 Feb 2017 14:06:31 -0800, John Robertson <sp...@flippers.com>
> wrote:
>
>>I have an older monitor from a video game - and it has a jitter on the
>>horizontal lines on the screen (vertical is locked), yet I don't see
>>this jitter on the H Sync. Using a signal generator (Cross-Hatch, Dot,
>>etc.) and all outputs are the same. Game source also shows same jitter
>>on same screen.
>>
>>It is not the WICO monitor signal generator as other B&W monitors show a
>>locked image.
>>
>>Schematics here:
>>
>>http://www.flippers.com/pdfs/TEC_TM-600_TM-623_Monitor.pdf
>>
>>Monitor has been recapped. Horizontal does lock, but jitter still present.
>>
>>Suggestions appreciated!
>>
>>Thanks,
>>
>>John :-#)#
>
> If the problem isn't HV arcing, check or replace parts from pin3 of
> the flyback including the 2 AFC diodes D401 and 402. The diodes on
> this line I'd just replace.

A dry joint is also possible, or a noisy part burned resistor dropping
feedback from a flyback winding to the phase discriminator.

Arcing usually isn't too hard to see - corona discharge can be, a faint
purple haze around any sharp pointy bit at EHT potential. Sometimes you have
to view the chassis with the light turned off to see it.

[John Robertson]

Sorry, been busy. The diode is soldered directly to the HV leads. So a
bad connection is out. The HV probe does not show any obvious signs of
jitter, but I suspect that would be the case seeing as the tube is a
giant capacitor and would smooth over most noise.

I also pulled the LOPT/Flyback and did both a ring test and a leakage
test - it passed both just fine, good ring count, and no appreciable
leakage using my old Heathkit R/L/C Bridge Cap checker (1960s - with
Magic Eye tube!).

Additional comments in response to other posts on this topic...

Thanks,

John :-#)#

[John Robertson]

Hi Chuck,

Thanks for the suggestions - I tried all that and no improvement in the
image quality. I used a couple of 1N43 Germanium diodes in place of the
AA143s, but (as I said) no change.

The only place I can 'see' a problem is when I monitor the cathode of
the picture tube. The horizontal section appears quite stable with no
flicker showing on my fast Tectronics scope.

Images:

Video - jitter on screen:

http://www.flippers.com/images/Horizontal_jitter_on_TEC_monitor.MOV

Scope - base of Horizontal drive:

http://www.flippers.com/images/Horizontal-drive-@-base

Scope - base of final video amp:

http://www.flippers.com/images/Base_of_final_video_amp

Schematic - base of final video amp (wrong version of schematic here
though):

http://www.flippers.com/images/Base_of_final_video_amp-scope

Appreciate any other suggestions. I haven't yet tried replacing the
resistors in the feedback loop, however the jitter doesn't show in the
loop...

Thanks!