Another HP-67 repair query

[coitboy2000]

Hi all

I am trying to repair an HP-67 I purchased as not working. I have searched the forum and compiled all the info and and schematics etc but thought I would ask the brains trust a few initial questions based on my probing of the calculator so far. It suffered from a battery leak and the terminals essentially dissolved. There wasnt much evidence the leak spread and I have given it a good clean. My observations initially are

- when connecting the battery terminals to by bench powers supply I notice the red led dot illluminates when I supply less than 3.6v. It draws about 90ma current.
- increasing the supply to 4v max the red light dissapears but the display is blank. The current draw increases to 110ma
- Initial probing indicates voltage is transferring to the cpu board but only 4.5v or so max.
- the sense amp chip gets pretty hot to touch. Normal ?

Any suggestions on what to start probing first would be greatly appreciated. I guess it may be a dead sense amp or power supply but I am unsure how to establish this for sure.

Cheers

Richard