Electronics > Repair

What more i can do?

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222Lab_Test222:

--- Quote from: Harry_22 on November 06, 2024, 10:18:01 pm ---Please do the following on the good (working) PC.
Go strictly point by point. Please see attached drawing.


--- End quote ---
1. On the board (disconnected from the Power Supply) measure the voltage at pin16  IS23.
After check the battery voltage. It should be 3,0V.
-It is 3V.
2. Measure the voltage at pin8  IS38.
-No Volt

3. Measure the voltage at jumper JP1.
-No Volt
4. Measure the voltage at jumper JP5.
-No Volt
5. Measure the voltage at jumper JP2.
-No Volt
6. Measure the voltage at jumper JP4 and JP6.
-No Volt

Please clarify the following questions:
7. Why is SW4 set up in different positions in your photos?
-I do not know what this does either BUT 4 pin of this switch is used to turn of buzzer if there is beep.
8. Why is SW2 set up in different positions in your photos?
-I do not know what this Switch does to be honest.

9. Remove SIM2 (Flash). Switch on the computer and check for beep. Switch it off.
-There is no beep at all, BUT the screen is black although it is on.
10. Remove SIM1 (Dram). Switch on the computer and check for beep. Switch it off. Install both SIMs back.
-There is no beep at all, BUT the screen is black although it is on and i see 1 or 2 unknown letters.
11. Remove IC40 (CGROM3). Switch on the computer and check for beep.
-I am not sure how to remove this, shall i desolder?

222Lab_Test222:

--- Quote from: Harry_22 on November 06, 2024, 10:18:01 pm ---PS
@Frank, it turns out that you found the datasheets for all the chips. I was wondering where such rare datasheets came from.
Only you can do this!

--- End quote ---

I do not know if he is same guy BUT "u/fzabkar" is his name in reddit. He help me a lot in past weeks, BUT unfortunately he couldn't help more and he drop out from further testing.

wasyoungonce:
PALCE16V8H, AMD, Universal Programmable Array Logic, 5V, 20-pin:
https://www.silicon-ark.co.uk/datasheets/PALCE16V8H-datasheet-amd.pdf

PALCE20V8Q, AMD, Universal Programmable Array Logic, 5V, 24-pin:
https://www.tomek.cedro.info/files/electronics/doc/ic_various/GAL20V8.PDF

Don't those have a data storage retention life....usually 20 years is given then programmed array data can degrade.  Page 2-58 of PALCE16V8 mentions this.

http://www.s100computers.com/Software%20Folder/GALs/Intro%20To%20GALs.htm

I program Atmel  AFT16V8BQL GAL EEPLDs (now Microchip) and other devices similar (ICT) and their datasheets also mention "20 yr" data retention life.

You can reprogram them...probably not in situ, usually easier to buy new one program it....if you have the .jed files (or what ever).

It may be possible to remove a working one and read it (if not read bit locked).   Then re-program other devices. (don't tick lock bit as you cannot read verify)   This may or may not be your issue.   I have seen similar devices degrade...that just count pulses

222Lab_Test222:

--- Quote from: wasyoungonce on November 07, 2024, 12:33:42 am ---
Don't those have a data storage retention life....usually 20 years is given then programmed array data can degrade.  Page 2-58 of PALCE16V8 mentions this.


--- End quote ---

Thanks for pointing it out, Lets me see if that's what causing the issues.

Harry_22:

--- Quote from: 222Lab_Test222 on November 06, 2024, 11:19:34 pm ---
10. Remove SIM1 (Dram). Switch on the computer and check for beep. Switch it off. Install both SIMs back.
-There is no beep at all, BUT the screen is black although it is on and i see 1 or 2 unknown letters.
11. Remove IC40 (CGROM3). Switch on the computer and check for beep.
-I am not sure how to remove this, shall i desolder?

--- End quote ---

What about the screen on non-working PC? Is it also on? Please check.

Don't remove IC40. Sorry, I didn't see that there is no bed underneath.

Please do the following on working machine:
Remove Sim1 (Dram) and try to start it.

PS
Every time before a new manipulation, check that the machine is working.

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