Help! I have an old video sculpture I built in 1995. It has three 9" B
& W monitors. They were originally obtained via mail order from Herbach
& Radman - they're just a circuit board and a CRT - it takes composite
input, operates at 12V.

Well, I just sold this sculpture to someone, and need to get it working
properly again. I tested the 3 monitors; two are good but one of them
will not hold a stable pictu no matter how carefully I adjust
Horizontal hold, Vertical Hold (and V. LIN.) it rolls and shudders side
to side, changes vertical rate (I think), won't lock in.

I had a spare, never-used CRT in storage. I took it out, hooked it up
exactly like the others, and it does the same thing! So that's two out
of four that are doing this. Seems doubtful that they would have bad
components, as they have very very little use and were stored away. I
must be overlooking something.

I don't know much about video circuits, so I would really appreciate
any illuminating comments.

I got help with these monitors on this newsgroup back in 1995. The
thread can be read he

http://groups-beta.google.com/group/...92d81106c78f24

I don't have the follow-up emails with Sam Goldwasser that helped me
iron out the original synching problem in 1995, but it looks like I did
install a jumper on an IC -The IC part number is: TDA1180P. (TV
HORIZONTAL PROCESSOR). I jumpered pins 8 & 9 (Vertical Sync. Separator
Input & Sync. Separator Input).
Thanks for any help.

***** Live Long and Phosphor *****

"Zephy" wrote in message
oups.com...
| Help! I have an old video sculpture I built in 1995. It has three 9" B
| & W monitors. They were originally obtained via mail order from Herbach
| & Radman - they're just a circuit board and a CRT - it takes composite
| input, operates at 12V.
|
| Well, I just sold this sculpture to someone, and need to get it working
| properly again. I tested the 3 monitors; two are good but one of them
| will not hold a stable pictu no matter how carefully I adjust
| Horizontal hold, Vertical Hold (and V. LIN.) it rolls and shudders side
| to side, changes vertical rate (I think), won't lock in.

What are you using to generate the signals?

N

What am I using to generate the video signal? Just an ordinary VCR.
Again, two of the monitors work fine, two have this unstable picture.
- Z

"Zephy" wrote in message
ups.com...
| What am I using to generate the video signal? Just an ordinary VCR.
| Again, two of the monitors work fine, two have this unstable picture.
| - Z

Well, if two work and two don't it's pretty sure it's the monitors.
Unfortunately at this point you really need someone with smarts and the
right equipment. I'd start with a scope on the vertical system and see what
the sync system is doing.

Be aware there's no short, simple solution for all cases. It's a matter of
working your way through the system until you find and replace as many parts
as are bad. That's why you have to train for 5 years to be qualified to fix
this stuff. TVs and monitors are complex devices.

N

On 22 Dec 2004 22:09:46 -0800, "Zephy" put
finger to keyboard and composed:

What am I using to generate the video signal? Just an ordinary VCR.
Again, two of the monitors work fine, two have this unstable picture.
- Z

Does the monitor sync with a DVD source? If it does, then I would
suspect some kind of flagwaving issue. This usually shows up as
horizontal jitters at the top of the screen. The TDA1180P IC has a
Time Constant Switch pin (12) and a Coincidence Detector pin (11)
which can be forced to accommodate VCR sources.

From the datasheet:
http://www.ortodoxism.ro/datasheets/...onics/1191.pdf

"To optimize the behaviour of the IC if a video recorder is used, the
state of the [coincidence] detector can be forced by connecting Pin 11
to earth or to + VS."


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

A flagwaving issue - is that related to the jingoism issue?

I couldn't get any of them to work with a DVD source (a PowerBook
laptop running a DVD - that's all I have). In any case, it's more than
jitters at the top of the screen: neither horizontal or vertical sync.
work. They roll in both direction, at increasing or irregular rates,
and there is and increase/decrease in brightness.

I noticed on the two that don't work properly that the TDA1180P IC is
getting very warm - almost too hot to touch - while with the two that
work, they don't get very warm.

I think it's time to order some of those chips. Who would you suggest
trying? DigiKey?

"Zephy" wrote in message
ups.com...
| A flagwaving issue - is that related to the jingoism issue?
|
| I couldn't get any of them to work with a DVD source (a PowerBook
| laptop running a DVD - that's all I have). In any case, it's more than
| jitters at the top of the screen: neither horizontal or vertical sync.
| work. They roll in both direction, at increasing or irregular rates,
| and there is and increase/decrease in brightness.
|
| I noticed on the two that don't work properly that the TDA1180P IC is
| getting very warm - almost too hot to touch

That seems odd. I wouldn't have expected those would get hot.

| while with the two that
| work, they don't get very warm.
|
| I think it's time to order some of those chips. Who would you suggest
| trying? DigiKey?

http://www.electronix.com/catalog/pr...oducts_id/9920

shows them at $2.49 ea. But I warn you that replacing them may not be the
solution. You are still guessing. It's possible that some other part has
failed causing symptoms and overheating.

NM

On 23 Dec 2004 19:54:09 -0800, "Zephy" put
finger to keyboard and composed:

A flagwaving issue - is that related to the jingoism issue?

http://www.videofortes.com.br/glossa...ideo_terms.htm

Flagwaving --- The sideways pulling and fluttering seen at the top of
a TV picture caused by a skew misadjustment or some other tape tension
error.

Some early TV sets required a mod (eg a jumper wire) so that they
would sync properly with VCRs. Others had a special channel optimised
for VCR use.

I couldn't get any of them to work with a DVD source (a PowerBook
laptop running a DVD - that's all I have). In any case, it's more than
jitters at the top of the screen: neither horizontal or vertical sync.
work. They roll in both direction, at increasing or irregular rates,
and there is and increase/decrease in brightness.

I noticed on the two that don't work properly that the TDA1180P IC is
getting very warm - almost too hot to touch - while with the two that
work, they don't get very warm.

The datasheet for the TDA1180P specifies an absolute maximum supply
voltage of 15V. Is your +12V supply really +12, ie is it regulated? If
not, is it also possible that 50/60/100/120Hz ripple from your supply
is affecting the IC?


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Seems doubtful that they would have bad
components, as they have very very little use and were stored away.

Some components certainly can go bad from lack of use and just being
stored away. Capacitors have been known to dry out. I would start
checking them.

"Jumpster Jiver" wrote in message
news:h9Pyd.17941$Ff3.11605@trndny04...
|
| Seems doubtful that they would have bad
| components, as they have very very little use and were stored away.
|
| Some components certainly can go bad from lack of use and just being
| stored away. Capacitors have been known to dry out. I would start
| checking them.

I get the impression that these were from a surplus dealer - maybe pulls. I
wouldn't overlook drifting resistors either.

NM

Thanks for your help and ideas. Yes I admit I was looking for the quick
fix. I'm going to need to remember my more in-depth troubleshooting
skills, limited as they are. (I worked as an electronics technician
about 20 years ago, used to do some component-level fixes of Macintosh
power supplies when I was working as a consultant, and have built small
projects). I do have a DVM and an oscilloscope, and 2 good units to
compare with. I wonder if I should invest in a capacitor checker. Kind
of makes sense that capacitors would be more likely to degrade than a
silicon chip or transistor. Would a resistor drift over time if there
were no current running through it? Yes, some of this is guesswork, but
it can be useful if in the exploration and exchange of ideas, I get
more of an idea where to focus once I get down to work.

"Zephy" wrote in message
ups.com...
| Thanks for your help and ideas. Yes I admit I was looking for the quick
| fix. I'm going to need to remember my more in-depth troubleshooting
| skills, limited as they are. (I worked as an electronics technician
| about 20 years ago, used to do some component-level fixes of Macintosh
| power supplies when I was working as a consultant, and have built small
| projects). I do have a DVM and an oscilloscope, and 2 good units to
| compare with. I wonder if I should invest in a capacitor checker. Kind
| of makes sense that capacitors would be more likely to degrade than a
| silicon chip or transistor. Would a resistor drift over time if there
| were no current running through it? Yes, some of this is guesswork, but
| it can be useful if in the exploration and exchange of ideas, I get
| more of an idea where to focus once I get down to work.

There are troubleshooting guides on the web, and many larger libraries will
have books on TV repair. I would start with the vertical and work my way
back trying to see if the sync system for it is working OK or not. That may
fix the horizontal as well.

N