Is my TI-58C hosed?

[jebem]

(10-24-2014 10:06 PM)Dave Britten Wrote:  Actually, yes. I'm pretty sure it was a failed memory chip, or something that's part of memory I/O. I ended up grabbing another one from ebay (the 58C is dirt cheap), and everything seems normal. Normal, but slow.

Thanks, Dave.

I have the same issue with mine.
The previous owner left the batteries inside and it leaked badly.
I have dismantled the machine piece by piece, put everything in the kitchen sink in warm water and dish soap for 15 minutes, then used a soft brush to remove the battery remains from the PCB and plastics.

Two days later I powered it on and it worked normally, except that it doesn't store in the registers or in the program steps. Just get zeros when reading.

However the current consumption is about 220mA, which seems too high for me, but I do not have another machine to compare.
Do you have a multimeter capable of reading in the 200mA region to check yours?
I would be very grateful.

A few things I have checked:

The voltages from the DC-DC power supply for the Texas IC's are fine:
Vdd = -10VDC (Pin 2 at CROM socket);
Vgg = -16VDC (Pin 1 at CROM socket);
Common point = Vss at +Vbatt. (Pin 8 at CROM socket).

Also the power supply for the TC5047AP-1 is fine:
Vdd = +4.8VDC (Pin 20);
Common point (GND at TC IC pin 8);

The large 470uF capacitor near the DC-DC power supply is a energy storage for this 5VDC SRAM IC supply, allowing the battery to be removed without losing the SRAM contents.

So my next step is to order one SRAM chip.