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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Sharp TV lost vertical, Questions about vertical output chip?
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 . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Sharp TV lost vertical, Questions about vertical output chip?
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 -- Please remove one 'i' from my address when replying by email. |
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