[JURB6006]

Hi;

Set came in with a triangular picture, found the side key value up in the 400s,
so I changed the EPROM (IC801). Now there is no convergence correction at all.

The are pulses on data and clock, but they disappear as soon as I go into the
convergence adjust mode and stay at 5V until the set is turned off and back on.

Now I was pretty careful not to put the IC in backwards, and I don't think the
set would run if I had (or would it ?).

Am I missing something here ?

Thanx in advance for any help.

JURB

 

[BWL]

When you say no correction, do you mean it won't adjust, or it just looks like
crap? if it's the former, you may have other problems in the circuit; the
latter, it needs a full convergence (about 2 hours).

 

[JURB6006]

When you say no correction, do you mean it won't adjust, or it just looks

like
crap? if it's the former, you may have other problems in the circuit; the
latter, it needs a full convergence (about 2 hours).

No convergence adjustment has any effect, as if the convergence yokes are
unplugged or the output IC is bad.

The fact that the pulses on the data and clock lines disappear when I access
the convergenge setup menu leads me to believe there's something fishy about
the new EPROM. I did change it again with no change.

Of course I have checked the output circuit and everything is there except
drive.

Now what ?

Thanx and thanx in advance.

JURB

 

[JURB6006]

I noticed a few other things now. Certain functions are missing.

In the initial menu video mute timeout is missing. In the conv misc menu
everything is missing except 1, 11 and 12, which are HVOL, TPVO and ODEV
respectively.

In the manual, it says there is supposed to be an item 16 EPWP, which is EPROM
write protect.

Seems like this has something to do with it.

Thanx again.

JURB

 

[Leonard Caillouet]

Do you have power supply to the outputs? These have tended to open the
fuses and/or chokes on the supplies.

Leonard Caillouet

 

[JURB6006]

Do you have power supply to the outputs? These have tended to open the
fuses and/or chokes on the supplies.

The answer to that, as usual raises questions.............

I have power to the STK 393, there is no drive. With the missing items in the
setup menu, this strongly suggests that the convergence subsystem is not being
initialized properly. To my knowledge, the output circuit cannot cause this.

I'm starting to suspect the set was sabotaged. Now I remember that once I reset
the errant parameter to normal, the convergence was good. In retrospect, why
only one parameter ? I did walk all through the service menus that I know of,
but now that i have changed the EPROM there is no going back.

The problem is probably in main system control. There is at least one option
missing from options menu that has nothing to do with convergence. Has to have
something to do with changing that EPROM.

Thanx again;

JURB