I-Inc iF191A - No Power, No Picture, No LED

[jayoung]

I have an I-Inc iF191A that does not power up, does not show any LED activity, and does not have an image on screen when a flashlight is used.

- I replaced all 7 of the caps on the power board with Panasonic FM series and nothing changed.

- The main cap reads 165.8 VDC.

- F101, F240, and F260 are OK.

- Pins to the video board:
BL-EN - 0.0 VDC
BL-ADJ - 0.0 VDC
5V - 5.5 VDC
GND - 0.0 VDC
12V - 12.6 VDC

- Pins to the front control board:
Audio L - 0.0 VDC
GND - 0.0 VDC
I KEY - 3.57 VDC (goes to 0.0 VDC when the I key is pushed)
MENU - 3.57 VDC (goes to 0.0 VDC when the Menu key is pushed)
POWER - 3.57 VDC (goes to 0.0 VDC when the Power key is pushed)
UP - 3.57 VDC (goes to 0.0 VDC when the up key is pushed)
DOWN - 3.57 VDC (goes to 0.0 VDC when the down key is pushed)
LED A - 0.0 VDC
LED A - 0.0 VDC
GND - 0.0 VDC
GND - 0.0 VDC
AUDIO-R - 0.0 VDC

- Voltage Regulator (pin 1 is on the right if looking at the voltage regulator with the pad to the bottom):
Pad - 1.97 VDC
pin 1 - 0.0 VDC
pin 2 - 1.95 VDC
pin 3 - 2.94 VDC

Hopefully this information can help with diagnosing the problem with this monitor and I appreciate any and all help from the members here with what direction I need to go from here.

[jsog]

Re: I-Inc iF191A - No Power, No Picture, No LED

C49 on the processor board looks slightly domed. The regulator is an 1117-33L, so the output should be 3.3V. But the input should be higher, maybe 5V.

[jayoung]

Re: I-Inc iF191A - No Power, No Picture, No LED

C49 on the processor board looks slightly domed. The regulator is an 1117-33L, so the output should be 3.3V. But the input should be higher, maybe 5V.

C49 is a ceramic cap below the C49 designation in the picture. I would assume you are referring to C41, but all of the caps on the processor board are flat (not to say that all of them are definitely good). I measured all of the voltages on the caps on the processor board.
C29 - 0.0 VDC
C41 - 1.19 VDC
C40 - 1.20 VDC
C39 - 3.66 VDC
C38 - 1.95 VDC
C37 - 1.94 VDC
C36 - 5.85 VDC
C21 - 3.63 VDC

It would appear that C37 and C38 are possibly on the side feeding the voltage regulator. I would wonder if it would be worth replacing at least those two caps.

[jetadm123]

Re: I-Inc iF191A - No Power, No Picture, No LED

Based on your voltage readings, it might be C36 that's the input to the regulator. The input pin of the regulator is the pin closest to diode D10. The input pin should be at approx. 5V. First, on the logic board, determine which of the 8 pins on the upper right connector (CN2) is supplying the 5V from the power board. Next, try tracing the path from that 5V pin to the input pin of the regulator. I suspect it might be going through C36 and D10. Check D10 for shorts.

[jayoung]

Re: I-Inc iF191A - No Power, No Picture, No LED

Based on your voltage readings, it might be C36 that's the input to the regulator. The input pin of the regulator is the pin closest to diode D10. The input pin should be at approx. 5V. First, on the logic board, determine which of the 8 pins on the upper right connector (CN2) is supplying the 5V from the power board. Next, try tracing the path from that 5V pin to the input pin of the regulator. I suspect it might be going through C36 and D10. Check D10 for shorts.

D10 resistance readings, positive/negative probes both ways:
78100 ohms
126600 ohms

Should I go ahead and un-solder it and test it out of circuit now? And if the readings are confirmed, look for a suitable replacement?

Part No. - 1N4007 and a cursive HG below it
I'm not sure what part would be the replacement from digikey?
http://search.digikey.com/scripts/Dk...=1N4007FSCT-ND

[jetadm123]

Re: I-Inc iF191A - No Power, No Picture, No LED

I not totally convinced that diode is bad. Have you tried verifying that D10 is indeed connected to the input of the regulator? Try measuring the input volage of the regulator again. This time use the first pin as ground and measure the input voltage (pin 3). With your negative probe still on pin 1, measure the voltage at each end of D10.

[jayoung]

Re: I-Inc iF191A - No Power, No Picture, No LED

I not totally convinced that diode is bad. Have you tried verifying that D10 is indeed connected to the input of the regulator? Try measuring the input volage of the regulator again. This time use the first pin as ground and measure the input voltage (pin 3). With your negative probe still on pin 1, measure the voltage at each end of D10.

I had to lean the diode D10 over to the side a little to be able to measure the voltage on both ends of it. I was not going to be able to have the negative probe on pin 1 and measure both ends of the diode on the back of the board. After leaning it over, I plugged the power in to measure the voltages and the LED came on. I was able to turn it off and on. I then hooked up the back lights to the inverter and a solid white screen appeared on the monitor (the ribbon cable to the panel was not hooked up). I hooked up the ribbon cable to the panel and connected the monitor to my computer and everything was working as expected. The best I can figure is a cracked or poor solder joint to the diode. I re-soldered both ends of the diode tonight and re-assembled the monitor and so far, everything is working great. I am typing this message using the monitor and it has been up and running for about 15 minutes now. I will continue to use it for a bit to see if anything changes.

A VERY big thank you to jetadm123 and jsog for all their help.

[jayoung]

Re: I-Inc iF191A - No Power, No Picture, No LED

The monitor is now working intermittently. I've had it work for a matter of hours and also a matter of minutes. I cannot seem to figure out exactly what is causing the intermittent no power, no LED issue. Should the voltage be the same on both ends of the diode D10? I will open the monitor up in the next day or two to get the voltages requested in Post #6. I needed to order some other parts from digikey, so I went ahead and ordered all of the caps on the processor board and also a replacement for D10 (http://search.digikey.com/scripts/Dk...=1N4007FSCT-ND).

[jayoung]

Re: I-Inc iF191A - No Power, No Picture, No LED

As an update, I replaced C36 and then tested the monitor. It continued to intermittently work. I could get the monitor to work by moving the diode (D10) from side to side while the power cord was unplugged and then plugging the monitor back in. I decided to replace the diode and so far it appears to have solved the intermittent power issue. However, I now have a new issue with the monitor. Green shows on the screen when it should be black and the picture appears grainy. This was not an issue prior to replacing the one capacitor and the diode. Any thoughts would be appreciated.

[jayoung]

Re: I-Inc iF191A - No Power, No Picture, No LED

I think I found the problem. The ribbon cable is installed with two "folds" in it from the factory and there is a break in the cable at one of the "folds." I can't seem to find a replacement through an internet search. Any suggestions?