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Author Topic: No signal from videopac  (Read 1013 times)
axell
Trying to get the cartridge in...
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Posts: 3


« on: November 19, 2018, 11:35:57 PM »

Hi!

I have had a videopac G7000 for some years. It has been working fine. But after I moved to a new place last year and now finally have the time to play with this toy it will not show anything on screen. The tv is the same and it is working fine with my amiga and megadrive. THe power supply gives 15v and 12v when plugged in.
I opened the console.

211231-1 rear on the pcb.

Found a diode on the backside of the pcb. it measures 0.6v each way. So I guess this could be broken?
it says ITT 17 and something i cant see on it. could this be the culprit?
I cant measure any voltage on the rf output.
Nothing looks burnt and no caps look faulty.
Can any body help me along?
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gertk
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gertk64
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« Reply #1 on: November 23, 2018, 01:09:11 PM »

Hi Axell,

Things to check first:

Do you have 5 Volts inside the console on parts like the CPU, and the TTL chips.

The RF output does not have a measurable voltage (at least not with a multimeter)
You mention that the Sega and Amiga work ok on the TV, which input do you use for these ?

For a standard/unmodified Videopac you need the Aerial/Cable input and you need to scan for channels after connecting and switching on the Videopac.
Also make sure you have a cartridge inserted during testing/searching for channels.


 
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
axell
Trying to get the cartridge in...
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Posts: 3


« Reply #2 on: November 24, 2018, 09:02:40 PM »

Checked all chips and there is 4.9v on all of them. Also 4.9v on the white wire to the rf module. Red wire is 1.2v and black is 0.027v.

The amiga use rf and the mega AV.
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gertk
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gertk64
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« Reply #3 on: December 02, 2018, 06:21:42 PM »

During scanning can you see the TV locking or the screen turning black on any channel?
If not it could mean that there is no RF signal at all.

If you have access to an oscilloscope you could check if there is video signal going into the modulator.

Or... you could build and AV modification and connect the Videopac to the AV input.

If you search this forum for 'AV output'  you will find some examples for G7000/Odyssey2
 
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
axell
Trying to get the cartridge in...
*
Posts: 3


« Reply #4 on: December 03, 2018, 12:28:55 AM »

There is nothing happening at all.

I do not have an oscilloscope. So perhaps I will have to try and build an av mod. I have tried to connect the audio out to the audio in on the tv, but no sound.
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