Troubleshooting PAL-1

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Georgios Dialynas-Vatsis

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Aug 5, 2022, 10:36:26 PM8/5/22
to PAL 6502 computer
I can't seem to get it working, power indicator displays that it's getting power. But when I press reset nothing happens.



GN L

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Aug 5, 2022, 10:52:35 PM8/5/22
to Georgios Dialynas-Vatsis, PAL 6502 computer
Hi Georgios,

Thanks for the front photo, could you please take a photo of back side just like the front, we can do a basic visual check.


> On Aug 6, 2022, at 10:36 AM, Georgios Dialynas-Vatsis <gdva...@gmail.com> wrote:
>
> I can't seem to get it working, power indicator displays that it's getting power. But when I press reset nothing happens.
>
> https://imgur.com/a/gXHWfcv
>
>
>
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Best,
Liu

Georgios Dialynas-Vatsis

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Aug 5, 2022, 11:21:32 PM8/5/22
to PAL 6502 computer
20220805_231749(1).jpg

GN Liu

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Aug 6, 2022, 7:04:01 AM8/6/22
to PAL 6502 computer
maybe its just the image quality, but I found at least one sus spot.

hty7PlqQ.jpg

eqzPdlws.jpg
__________________________________________________
upper is from nils, THANKS NILS'S HELP! 
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if you can confirm that the solder joints are ok, can you do some continuity test on the power trail, data bus, address bus and control lines (from IC pins to the expansion socket pins). 

Then you can check whether the reset operation is activated by the RS button, the RESET pin on processor needs go from high to low, this can check the 556 (U4) chip.

After, you will find some inspiration in the 74LS145 myth just discovered (https://groups.google.com/g/pal6502/c/KPfvKGdgOcQ), each one of these two chips can cause the on-board LED display won't light up, one (U1) is to drive the LEDs, another (U5) is address decoding.

Thanks,
Liu
On Saturday, August 6, 2022 at 11:21:32 AM UTC+8 Georgios Dialynas-Vatsis wrote:
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