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-   -   HP 150 Touchscreen II repair (https://www.vintage-radio.net/forum/showthread.php?t=193024)

gridrunner 7th Oct 2022 4:23 pm

Re: HP 150 Touchscreen II repair
 
3 Attachment(s)
Hi everyone,

So, these HP 150s are now multiplying!

I recently picked up a HP 150 model 1, with the touchscreen and a printer, keyboard and a disk unit the HP9122.

The printer, like the previous unit is toast because the ink cart was left in.
The previous owner said the machine was working when put away but it now no longer comes on.

I've stripped the machine down and discerned a problem right way. Damned batteries. The pair of LR1 cells for the cmos backup had corroded and leaked onto the video PCA board. In a very bizarre way the green goblin had furred the majority of the exposed PCB joints and IC legs on most of the component side and had even managed to reach the connector at the far end of the board! That said, it hadn't done any NICAD level of damage, so there's no discernible damage to traces.

I've cleaned it off and paid special attention to the connector to the backplane.
I've replaced some out of spec and leaking capacitors on the power board and carefully cleaned the touch screen photocells.

The power supply is healthy, but on power on there is no display and no start up beep.

I referred to the service manual and decoded the LED self test codes as:

D5AA - video chip 5 error
D8FF video chip 0 error

https://youtube.com/shorts/bLg_V8SVm1k?feature=share

I suspect the corrosion to the video board has done some damage. Any thoughts would be appreciated!

thanks


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