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hyuma

Trying to fix Colecovision PAL rev. D

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You had color in your other videos though.  But you also had digital graphics corruption.

 

Pins 1 and 18 of the 1889 should have a 4.43MHz sine wave on them.

Edited by ChildOfCv

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You had color in your other videos though.  But you also had digital graphics corruption.
 
Pins 1 and 18 of the 1889 should have a 4.43MHz sine wave on them.
I haven't nothing similar on that pins and also I replaced the oscillator with the same model and the situation didn't changed at all.. I tested 3 different new oscillator and still don't know why I haven't the 4.3mhz wave..

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17 minutes ago, hyuma said:

I haven't nothing similar on that pins and also I replaced the oscillator with the same model and the situation didn't changed at all.. I tested 3 different new oscillator and still don't know why I haven't the 4.3mhz wave..

Make sure there is +12V at Q20 pin 2.  This should turn the transistor off so that it doesn't interfere with the oscillator.  Q20 pin 3 should be much less than 12V.

 

Q23 pin 2 should be about 4.3V.  Q23 pin 1 should be around 3.9V.  Q23 pin 3 should be around 7.4V.

 

All voltages taken with the black lead on ground.

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Make sure there is +12V at Q20 pin 2.  This should turn the transistor off so that it doesn't interfere with the oscillator.  Q20 pin 3 should be much less than 12V.

 

Q23 pin 2 should be about 4.3V.  Q23 pin 1 should be around 3.9V.  Q23 pin 3 should be around 7.4V.

 

All voltages taken with the black lead on ground.

Q20:

 

Base: 11.17v

Emitter: 11.93v

Collector 11.90v

 

 

Q23:

 

Base: 4.24v

Emitter: 3.50v

Collector: 7.86v

 

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1 hour ago, hyuma said:

Q20:

 

Base: 11.17v

Emitter: 11.93v

Collector 11.90v

Q20 is wrong.  What's the voltage on the other side of R137?  And do you have anything plugged into the expansion module?

Edited by ChildOfCv

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Q20 is wrong.  What's the voltage on the other side of R137?  And do you have anything plugged into the expansion module?
Voltage is about 5.45v. And no, I don't have nothing plugged on expansion module

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6 hours ago, hyuma said:

Voltage is about 5.45v. And no, I don't have nothing plugged on expansion module

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That's way too low then.  The control you're reading now activates external video and has a pull-up resistor R160 to hold it at 12V until something pulls it down.  The external video enable pin is 32 (bottom side, second from right) at the expansion slot.  Make sure R160 is 12V on one side.  Really, it should be 12V on both sides, but you said you're reading 5.4 instead.

 

If you can't find a reason for the external video to be loaded down (solder bridge, cracked solder joint, etc) then try removing U30 to see if it improves.  If not, put it back and remove U31 and repeat the voltage test.

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That's way too low then.  The control you're reading now activates external video and has a pull-up resistor R160 to hold it at 12V until something pulls it down.  The external video enable pin is 32 (bottom side, second from right) at the expansion slot.  Make sure R160 is 12V on one side.  Really, it should be 12V on both sides, but you said you're reading 5.4 instead.
 
If you can't find a reason for the external video to be loaded down (solder bridge, cracked solder joint, etc) then try removing U30 to see if it improves.  If not, put it back and remove U31 and repeat the voltage test.
I have 5.4v on one side of R137... I never measured yet R160

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