Sharp Image 33"

FrizzleFried

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Picked up a showcase cab that has a Sharp Image 33" or 34" monitor in it. The image looks great aside from the fact it's very pincushioned. The pincushion pot on the remote board seems to do "something" but what it does is very little and it doesn't resolve the pincushion issue.

Could it be as easy as a bad pot? Does anyone know the pot value on one of these remote boards?

The game currently running in it is Police Trainer.

Thanks!
 
It appears that this is a SI DS727R-DS... which seems pretty short on docs available. I found Mod's capkit list (thanks!), but I need to replace pots. Does anyone know what values the "SUB BRIGHTNESS" pot on the neck board would be? How about the PIN CUSHION pot on the remote board?
 
OK ... looking closely at the pots most have "205" printed on them. A couple have 201 printed on them...HPOS has c05 pinted on it and the pincushion one (the one I need) has e02 on it...

EDIT: Yes... I am a dumbass... I realized I was reading things UPSIDE DOWN just after I posted this...

It looks like the pincushion pot is a 203... which should be 20K ... right?
 
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OK... determined POT values and replaced them...

The pot that went in to the neck board fixed the sub-brightness issue perfectly...

The pots that went in to the pincushion/horizontal size did nothing beneficial. I still get a slight pincushion adjustment and a slight horizontal size adjustment. I would guess the size of the image is about 20-25% too wide...

I went to adjust the horizontal coil and found there to be "no hole" to stick a tool in to to adjust. It "feels" flat inside the "tube" of the coil. I say "feels" because the coil is in a position I can't "see" inside of it. It could be that something was broken off in there but I'd guess I'd "feel" if that was the case but it doesn't seem to be.

Can anyone make any suggestions RE: these issues and this monitor?
 
Oh... and while I did find 2 pins labeled (N) and (W) for normal and wide... the monitor was already on Normal... I tried Wide and it made the screen even a little wider.

Basically... looking at the POLICE TRAINER titlescreen... the P and R is cut off on each side.
 
Oh yeah... I am getting TONS of love with this post.

;)

Wondering... would a high-B+ cause the wide image? Any idea where I would check the B+? There are two pots on the chassis itself. One is labeled X-RAY and it's the cutoff circuit from my understanding. That leaves one more I can't read... I am guessing that would be the B+...

Any confirmation would be awesome. Also, any help with a test point for the B+ and what it should be set at? 130V?
 
Si-727

Is there Any way you can take a picture with the chassis

out and a picture over the top of the chassis

close enough that the parts are visible

and i or we can point out test points and the parts

that would cause these symptoms?

And along the heatsink around the flyback.
 
Dunno if it will help... but Mod posted this image of this chassis...

Close enough?

SI727RDSMainBoard2.jpg
 
SI-727-DS or Dual Scan

I was looking for a picture of your chassis
not his, So if i notice a visual symptom
with your parts that would be a clue something
wrong in that area..Theres noway to fix this
chassis without removing it and test parts!!


The PS secondary parts are not in the picture so i can't
point out the parts i would have because there not in the
picture.For b+ test point.

The suspects would be the polyester axial HV caps
or dual diode. The daughter board could have a shorted
part on it, and a good PM is needed on it like solder connections.

In some case's the a stacked dual diode is cooled and mounted
to a heat sink of some kind..I was looking for these parts
on the big black heatsink.It may be the fat diode seen in the
picture check it too.

A cap kit maybe needed but not the direct issue here
from my experience.


The closer the yoke return pulse to ground reference
the wider the picture..
 
I was looking for a picture of your chassis
not his, So if i notice a visual symptom
with your parts that would be a clue something
wrong in that area..Theres noway to fix this
chassis without removing it and test parts!!


The PS secondary parts are not in the picture so i can't
point out the parts i would have because there not in the
picture.For b+ test point.

The suspects would be the polyester axial HV caps
or dual diode. The daughter board could have a shorted
part on it, and a good PM is needed on it like solder connections.

In some case's the a stacked dual diode is cooled and mounted
to a heat sink of some kind..I was looking for these parts
on the big black heatsink.It may be the fat diode seen in the
picture check it too.

A cap kit maybe needed but not the direct issue here
from my experience.


The closer the yoke return pulse to ground reference
the wider the picture..

Bob is sending me a cap kit. I'll start there. When I have the chassis out I will take detailed photos of the chassis from all angles and we'll go from there.

:)

Please remember... my technical level isn't much above "replace this cap"... "replace this diode"....

:)

Thank you!
 
ok

Bob is sending me a cap kit. I'll start there. When I have the chassis out I will take detailed photos of the chassis from all angles and we'll go from there.

:)

Please remember... my technical level isn't much above "replace this cap"... "replace this diode"....

:)

Thank you!


I bet a beer its not a electrolytic..?

with picture i will id the questionable parts.

A shorted part is the easiest part to find!

Switch it to standard as see how the image looks too.
 
BTW... if you help me get this thing going right I'll buy you a sixer of your favorite import....
 
Welp... it looks like I won't be buying any beers... ;)


I pull the chassis and immediately notice this bad boy...

attachment.php


I recap the chassis and end up with no new cap for that position (I will be emailing Bob). It's a 4.7uf 50v NP... great. Luckily I found one in a Sanyo 20EZ kit from Bob (he'd overcompensated for the 25v that chassis calls for) and....

attachment.php


Amazing what a cap kit will fix ...
 

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I owe you a Beer..Smile

A non Polarized cap is the only type that could apply

and they are used in most all pin amp circuits for dual res

I have found C729 in the K7400 to have an issue

with the width in the pincushion circuit and not be

obvious that it was bad..

and i dont think any kit has those caps in it

and they should be, I replace them but i have all the caps

on the shelf ready to install, but it should be replaced

along with the other electrolytics and all chassis that need a cap kit!

I hope you learned a lesson that you should look for the obvious

bad parts before ordering parts!! After all i told you to take it out

and take a picture before i bet you!!
 
Bah... these were obviously the original caps. It was time...

:)

But yeah, I was pretty sure of the problem after 2 seconds of looking at the chassis.
 
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