IBM 5160 computer CRT issues

[willycp]

Hi, I have a 5160 IBM computer that has been in storage for 10-15 years (outdoor type structure) in its original burlap container. In testing it and finding it wasn't working, we've opened it up to check on the insides. It appears to be working as we were able to direct the video output to another screen. There is a problem, though, in getting it to use the CRT screen. In working through the problem we have determined that the power supply is good on all leads and the the internal power board is getting power. Haven't determined yet if the board is passing power on to the tube yet. We are just wondering if anyone has any experience with this type of problem. The tube appears dead, but if it isn't getting any power it would look that way. Any suggestions as to where we might look for a problem area? Or has anyone else seen this type of issue with the 5160s before?
Thanks for any and all help you may be able to give me.
Bill

 

[NeXT]

What type of monitor is it? IBM 5151? 5153?

 

[willycp]

Sorry, My info is a bit wrong. I don't have the computer here with me, it is with a friend who is attempting to fix it. The computer is an IBM 5155 model with a Zenith DS9CNFI monitor. Thanks for your reply, looking forward to hearing back from you.
Bill

 

[retrogear]

I fixed that exact model a year ago for someone. It had a shorted horizontal driver transistor Q102 and a burned 10 ohm resistor RX124. I used a 2N3904 for the transistor and as far as I know the CRT is still working ok. Here's the
schematic with the parts circled and a voltage measurement to confirm the flyback is running with the new transistor.

Larry G

 

[willycp]

Thanks, we'll check and see if any of the things you've mentioned could be our problem. I do appreciate the information you've sent.
Have a great day.......
Will let you know how your recommendations work out....
Bill