|Re: HP97 restore project (mother board)|
Message #10 Posted by Alberto Fenini on 6 Jan 2010, 5:47 p.m.,
in response to message #8 by Eric Smith
And here we go, that's what I did today ...
ACT from HP25 soldered on HP97
how far I went .....
Since the result wasn't what exactly I had expected, I have re-soldered the original ACT chip, and surprise surprise, I'm now in the situation where a flickering and random bunch of zeroes will light up for a second when the switch goes from off to on ...too fast to take a picture...
I can also hear the printer making noise if this is of any importance.
However, since on both units (I'm using a working HP97 to test progresses)the printer gear needs to be replaced,I have to keep the printer switch in manual mode.
I have then decided to divide the project in two sections : motherboard repair and display with keyboard repair
At this point, I'd like to hear some suggestions from all of you. What can I do with the described behavior ? On the motherboard I have re-soldered most of the chips, and I could do it radically, if anyone would suggest that a bad contact could be the reason of this behavior.
As for the display/keyboard unit, when used with the working motherboard, it reamins completely off .... Would you suggest replacing the chips ? I have noticed that the transistor arrays (1858-0044)are exactly the same used on the printer card, so I could easily have a source for them. I know these to work since I have swapped the printer unit back and forth in the past.
Or would you suggest that the 1820-1629 could be responsible for the display remaining black ??
Any, and I mean any, suggestion will be of great help, and I'll be glad to try it out.
Take care, Alberto