No picture from G7000

[Atha]

I have this G7000 that used to work but now is completely woithout picture and sound. I have tried connecting to AV channel of my tv set.

 

The pcb has three big ICs( Intel P8048 0046, Intel 8245, Motorola 612192-1). They all get a little warm. There are two 7836 with heatsinks. They get hot after a few minutes. Is that normal?

 

I have checked the three caps on the pcb and they show the value on them.

 

On the output to the rf module I measure 4.7v and about 1v.

 

The psu says 12v when plugged in to the videopac.

 

Any suggestions to what else I can try/check?

[emerson]

Im not familiar with the G7000, does this output composite video or rf signal? The way you described it sounds like you connected the rf output of the G7000 to composite input of the tv. If its an rf signal you should connect the G7000 to the coaxial input of the tv and try channels 2-3-4.

 

If you have an oscilloscope you could check to make sure the system clock is good. If there is a reset button press it and measure for a state change on the reset pin of the cpu.

 

Is the rf module internal or external? If internal there should be a few pins on it (power, video, audio, and maybe some others). Test those to see if one of them resembles a video waveform. Also test the output of the rf module for a similar signal. if external try opening it and test for continuity along all cords coming out of it.

[Atha]

No I connected rf to rf and then tried and connected the composite from G7000 to composite tv. The G7000 only has rf output(internal). The composite was found inside were the rf module connects to the rf module. THe pins you are mentioning. think the red wire is composite and it gives me a 1.1v. white gives 4.9v and black 0.027v

 

I dont have an oscilloscope

I measured the ohms of the rf output to 173.

[emerson]

A service manual can be found here although its not in english. Is this the same unit? https://archive.org/details/G7000_Service_Manual_198x_Philips_M6

 

Do you have a composite mod installed? You can't always tap composite video directly from the motherboard and have it work. If you do have a mod installed try removing it and use just the rf.

 

You can still test the reset pin of the cpu for a state change with a multimeter. Tie the negative lead to ground and the positive lead on the reset pin and note the current state. Hold the reset button in and you should see a state change. It looks like pin 4 of the 8048 is active low reset.

 

Have you tested the fuse or other parts in the power circuitry? Check your diodes and any voltage regulators or transistors. Test to make sure all ICs have the correct voltage. Some memory ICs require a negative voltage so check for that as well.