squished vertical in Sharp 3LS36 color TV
 

I need help fixing the squished vertical in my Sharp 3LS36 TV. This is a
mini color set from 1986. You can view the symptom at:

http://antiqueradio.org/art/temp/Sharp3LS36Screen.jpg

A piece of the schematic showing the vertical circuits is at:

http://antiqueradio.org/art/temp/Sharp3LS36sch1.jpg

I have replaced C501, C502, and C503. I measure 9.4vdc at pin 14 of the IC,
as spec'd. At pin 13 next door, however, I measure close to zero, rather
than the 6.8vdc called for.

Ideas? This kind of project is a little beyond me. I can fix old tube
radios, but don't have solid-state expertise or equipment. So any hints
would be much appreciated.

Thanks!

Phil Nelson

Can be C509, 502, 506, 503. These are very likely to give this type of
fault.

Use an ESR meter to properly check the caps, or change them.

--

Jerry G.
======

"Phil Nelson" wrote in message
link.net...
I need help fixing the squished vertical in my Sharp 3LS36 TV. This is a
mini color set from 1986. You can view the symptom at:

http://antiqueradio.org/art/temp/Sharp3LS36Screen.jpg

A piece of the schematic showing the vertical circuits is at:

http://antiqueradio.org/art/temp/Sharp3LS36sch1.jpg

I have replaced C501, C502, and C503. I measure 9.4vdc at pin 14 of the
IC, as spec'd. At pin 13 next door, however, I measure close to zero,
rather than the 6.8vdc called for.

Ideas? This kind of project is a little beyond me. I can fix old tube
radios, but don't have solid-state expertise or equipment. So any hints
would be much appreciated.

Thanks!

Phil Nelson

You have to be willing to replace capacitors . Read posts on antique
radio :-)

"Phil Nelson" wrote in message hlink.net...
I need help fixing the squished vertical in my Sharp 3LS36 TV. This is a
mini color set from 1986. You can view the symptom at:

http://antiqueradio.org/art/temp/Sharp3LS36Screen.jpg

A piece of the schematic showing the vertical circuits is at:

http://antiqueradio.org/art/temp/Sharp3LS36sch1.jpg

I have replaced C501, C502, and C503. I measure 9.4vdc at pin 14 of the IC,
as spec'd. At pin 13 next door, however, I measure close to zero, rather
than the 6.8vdc called for.

Ideas? This kind of project is a little beyond me. I can fix old tube
radios, but don't have solid-state expertise or equipment. So any hints
would be much appreciated.

Thanks!

Phil Nelson

This is a fairly straightforward push-pull output, like the audio
output stage of a cheap radio. Do you have a scope and any sample
waveforms? I would be suspicious of C509, it is in the return path to
ground of the vertical yoke.

H. R.(Bob) Hofmann

Can be C509, 502, 506, 503. These are very likely to give this type of
fault.

Forgot to mention that I already changed C509 (as well as 501, 502, 503 as
mentioned in original post). Haven't tried 506 yet, though.

Thanks!

Phil

On Wed, 10 Nov 2004 18:55:54 GMT, "Phil Nelson"
put finger to keyboard and composed:

I need help fixing the squished vertical in my Sharp 3LS36 TV. This is a
mini color set from 1986. You can view the symptom at:

http://antiqueradio.org/art/temp/Sharp3LS36Screen.jpg

A piece of the schematic showing the vertical circuits is at:

http://antiqueradio.org/art/temp/Sharp3LS36sch1.jpg

I have replaced C501, C502, and C503. I measure 9.4vdc at pin 14 of the IC,
as spec'd. At pin 13 next door, however, I measure close to zero, rather
than the 6.8vdc called for.

I'm betting that C509 has dried out. I'd change C506 as well.

Vertical size appears to be regulated by sensing the voltage across a
2 ohm resistor. The current through this resistor is the vertical yoke
current. Pin 15 of the IC is the feedback pin.


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

"Franc Zabkar" wrote in message
...
I'm betting that C509 has dried out. I'd change C506 as well.

Replaced C509 and C506. Still no improvement.

Vertical size appears to be regulated by sensing the voltage across a
2 ohm resistor.

Do you mean the 2 ohm resistor that looks like it's in package (M601) along
with a 820 ohm resistor ?

Thanks!

Phil

Phil,
Unsavory as it sounds, you may have a shorted turn in the
yoke vertical winding, as process of elimination narrows down the
possible culprit.
Bill(oc)

Ouch. Dare I ask how a numbskull like me might test for that condition?

Regards,

Phil

"Bill Sheppard" wrote in message
...
Phil,
Unsavory as it sounds, you may have a shorted turn in the
yoke vertical winding, as process of elimination narrows down the
possible culprit.
Bill(oc)