Gateway EV910B CRT Monitor - Power On Diag

[RufiS]

[RufiS]

Power.jpg


No Power.jpg

[RufiS]

Why does the KEY line never show up again? I find it here but nowhere else. Refer to schematic pg 46.

[R_J]

Do you have +12v and +5 volts coming from the power supply? you can check them on IC904 and IC905
If you are not getting any secondary voltages, check that R906 is not open, if it is open IC901 is likely bad, If R906 is ok, I would try replacing C905 & C906
If you trace the Key line on the board from P402 pin 5, it goes to u_COM pin 40 (KB01)

[RufiS]

Thank you very much for the direction you pointed me in.

I went to check IC904, was seeing 1.3volt on the I pin. Went to check IC905 and when I made the connection with my meter probes to the I pin the CRT powered on completely. Green light, then the light went Amber(standby) after a few seconds as would be expected when powered on and not connected to a VGA signal.

Now
Not in Standby
IC904 :
Pin I = 15.32V
Pin O = 12.14V

IC 905 (Not Standby)
Pin I = 14.6V
Pin O = 4.99V

In Standby
IC904:
Pin I 1.39V
in O 0.06V

IC905:
Pin I = 6.62V
Pin O = 4.99V.

With that said, technically the monitor is power on now. With that said, I had my Negative Probe on my meter touching the chassis when I probed pin I on IC905 and the device powered on. Not sure why it powered on when I did that and I don't want to just say the issues is resolved and have it come back again.

[R_J]

You could start by checking for poor solder connections around those regulator ic's I suspect over time there may be some poor solder connections, also replace those two electrolytics in the primary, (C905 & C906) there may be other weak caps in the power supply ie: C917, C912 etc.
Post some clear straight on pictures of the trace side of the board, especially the power supply section.

[RufiS]

Thanks. Yeah, thinking maybe a solder joint on IC905, or bad cap that I "tickled" by connecting the voltmeter. Going to touch up the joints incase, and replace C905 and C906 just as a matter of maintenance. Thank you! I love this monitor and have been using it for the past 13 years and hope to get many more out of it.

[RufiS]

Should have also mentioned that before the system powered up by trying to check the input voltage on IC906(no power button press required, just came to life out of nowhere (and I was unable to reproduce this), IC904 had like 0.?V on the input but it wasn't 0V. Afterwards, the Inputs on both show the same voltage as in standby mode. Afterwards I was only able to effect the power on/off state by using the power button.

Also of note, part of the original issue was the power button was not powering on, or off, the device. It was either stuck on, or I had to take the swivel off the bottom, and tap the bottom while plugged in for it to power on after a power loss, which made me feel suspicious of a solder joint, then later when discovered that the fuse was wonky, i blamed that.