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December 06, 2019, 09:05:32 PM *
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Author Topic: G7000/00 (no pictures) ?? special measuring points for multimeters or Oszilos  (Read 352 times)
g7000Mikel
Trying to get the cartridge in...
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Posts: 3


« on: May 17, 2019, 03:14:00 PM »

Hello I'm Mike  Smiley l, and usually collect more 8-bit computers.

But I think the G7000 is cool.
I have a very early model here, namely the G7000 / 00
This has silver joystick (pluggable) and external power supply.
Unfortunately, the console is broken. No picture on channel 32.
I try now to find the error step by step.
I will first measure the two 5V voltages.  I have only found newer schematics so far. (from G7000/22 or above)
I also have an oscilloscope. Can I somehow measure the CPU? The system clock or something else

Thanks for any hints.
I will also deliver more pictures.
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g7000Mikel
Trying to get the cartridge in...
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Posts: 3


« Reply #1 on: May 17, 2019, 04:32:03 PM »

I took some pictures now.
For another test, I borrowed a functioning G7000 / 20 and put the three big ICs of my defective G7000 / 20 board in there first.
Happiness is first: all three ICs work in the other G7000.
The 5V voltages are on both voltage regulators o.k.

Question: I have on the old G7000 / 00 a TV modulator with only three ports, the newer G7000 / 20 has 4 ports (4th is apparently only screen).
I have for a test, the old modulator connected to the G7000 / 20, but unfortunately it comes with no picture.
Otherwise not. when I connect the working G7000 / 20 modulator to the old G7000 / 00.

What can I do next?
A direct video output, I probably can not get the G7000 / 00, because the board is different than the newer PCB.
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g7000Mikel
Trying to get the cartridge in...
*
Posts: 3


« Reply #2 on: May 21, 2019, 09:15:08 PM »

so, I have now swapped the IC and measured the CPU frequency with 5.8Mhz.

The video signal also looks active, I have cleaned the socket for the modules and the entire device together again.

Result: the console is working again, but I do not know why.
The picture is actually on TV channel 32 o.k.

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