Sharp model 25A-S100
Vertical output chip NTE7039

In the past TV had intermitant vertical problems, resoldered pins 13,
12 and 11 on NTE7039, good for two years. Now have just horizontal
line acroos screen. No schematic.

Questions
Pin 8 pump-up output, does the chip supply that Voltage or another
circuit?
Pin 2 is this 4.45V over driving the trigger, cause of failure?
Pin 13 Where does this Voltage come from?
I can order a NTE7039 for $10.00.
Just not sure if it's the NTE7039

Thanks for any info

pinout My readings data specs

1 +VCC1 10.29 V 8-14 V
2 Vertical trigger input 4.45 V
Max 3.2 V
3 time constant 5 V
4 Vertical amp control 5.2 V 5.9-6.3 V
5 Vertical size control -.004
6 Ramp generator 4.96 V
4.6-5.2 V
7 Vert out AC/DC feedback -.006
8 +Vcc8 -.282 V 10-27 V
9 pump-up output -.208 V
10 OSC stop -.001 V
11 Grnd
12 vertical output -.004 V
13 Power supply for vertical output -.004 V Max 62 V


Features:

Low Power Dissipation due to On–Chip Pump–Up Circuit

On–Chip 50/60Hz Vertical Size Control Circuit

On–Chip Sawtooth Wave Generating Circuit

On–Chip Drive Circuit

Vertical Output Circuit

On–Chip Thermal Protection Circuit

Excellent Interlace Response

Excellent Crossover Response

Recommended Operating Conditions: (T A = +25....C unless otherwise
specified)
Parameter Symbol Min Typ Max Unit
Driver Supply Voltage +V CC 1 8 12 14 V
Pump–Up Supply Voltage +V CC 8 10 24 27 V

Absolute Maximum Ratings: (T A = +25....C unless otherwise specified)
Driver Supply Voltage, +V CC 1 max 15V . . . . . . . . . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pump–Up Supply Voltage, +V CC 8 max 30V . . . . . . . . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Supply Voltage, +V CC 13 max 62V . . . . . . . . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Deflection Output Current, I DEF –1.5 to +1.5A P–O . . . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Resistance, Junction–to–Case, R thJ–C 4....C/W . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Allowable Power Dissipation (With Infinite Heat Sink), P D max 8W . .
.. . . . . . . . . . . . . . . . . . . . . . . . .
Operating Temperature Range, T opr –20.... to +85....C . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Temperature Range, T stg –40.... to +150....C . . . . . . . .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

On Sun, 24 Sep 2006 03:46:19 GMT, Mike put
finger to keyboard and composed:

Sharp model 25A-S100
Vertical output chip NTE7039

This is a replacement for the LA7838.

See http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm

In the past TV had intermitant vertical problems, resoldered pins 13,
12 and 11 on NTE7039, good for two years. Now have just horizontal
line acroos screen. No schematic.

Questions
Pin 8 pump-up output, does the chip supply that Voltage or another
circuit?

Vcc8 is an externally supplied power rail. Look for a feed from a
secondary winding on the flyback transformer. You'll probably find an
open, low value, fusible resistor.

A datasheet, including application circuit, for the LA7837 and LA7838
is available he
http://www.audiolabga.com/pdf/LA7837.pdf

- Franc Zabkar
--
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