Got this unit in today totally dead but when i removed connector (cn701)the lamps came on momentarily and if you put it half on lamps all come on.Power supply seems to work fine.All 24vdc present on cn903 and all on cn902 except on/off .43vdc and dim 0vdc.The trouble points towards main board as the metal cover/heat sink in middle of board is quite hot to touch.All voltages on cn701 except pwr and bl_on and bl_br.Voltages present to ir sensor and buttons.
Insignia 32" NS-32E740A12
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by cajoegHello, I'm new to the group and to trying to repair a LCD TV. During the past few years, I've been collecting/repairing/restoring vintage personal computers (Commodore, Apple II, Atari, TRS-80, Texas Instruments, and Timex Sinclair). This has been my retirement hobby. Now I've gotten interested in trying to repair a LCD TV that I have and used regularly when working on vintage computers.
The LCD I'm working on is a Insignia NS-LCD019. I've downloaded the service manual that I could find, but it must be a different revision since not too many items in the service manual match the TV... -
by valvashonHaving a new problem with the 19" Insignia that I modified with one of my automatic turn on circuits. That is now completely disconnected so that is not the issue. I was doing some modifications on that circuitry and managed to short something out on the underside of the power board.
Actually found and bought the service manual (who knew it was even available?!) which brought me to the High Voltage Startup Circuit controller chip.
Looking up that chip number- LD7575APS brought me to the attached datasheet. I have marked my voltage readings on the schematic sheet (open in new... -
by tbsmithThere is voltage on the bridge rectifier and main caps (163V). Fuses all check good. One of the smaller electrolytic caps (C9112 which is 50V, 100uF) looked bloated, it measured 60uF with one tester, and defective with another. I replaced it temporarily with same uF rating, higher voltage since I don't have the exact one. I also found that one of the switching mosfets (for lower voltage DC supply I think) was shorted. It is a 50R800CE which I didn't have, but had something with the same voltage and current rating and a similar Rds. None of these fixes helped. I'm out of ideas. Any suggestions...1 Photo
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by howardc64Eventually discovered a burn mark near lower corner of LCD. Here is a summary
- Backlight on, no image
- Disconnect right buffer board (view from front), left side display comes on
- Masked off pin 7+8 (both ~12,5v on both left and right buffer board) from t-con to right buffer board (view from front) display works but have some lines
- Buffer board is pretty simple
07-11-2025, 04:04 PM -
by angelosHi Guys,
It's been a while that i have been active on the forum, sorry for that. My primary job has been keeping me quite busy.
The above set starts up with sound working just fine but the CCFL lamps (Inverter) runs for one second and switches off.
My 24V supply is steady and the ON/OFF pin to the inverter is at +5V.
The only thing i see is the PWM signal pin is at +5V without any square wave being emitted. Is this normal? as far as i can remember there needs to be a square wave pulse there. Am i right?
I will now measure with my oscilloscope probe on... - Loading...
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