Hello there,
I am hoping that somebody will find the reason why my C64 displays a black screen. I checked all voltages, they seem all okay (I have three power supplies, black screen with all of them).
I have a thermal camera, so I attach a snapshot of the motherboard. For some reason the coloring is shifted by approx. 1 IC width towards the top. As expected (roughly from top to bottom):
- The two voltage regulators are warm.
- The VIC-II chip is warm too.
- The audio IC (the hottest at 48.4C), the processor, the PLA are all warm.
- One memory chip has a hot spot.
I have two VIC-II chips on order to see if they change something.
I also have the PLAnkton EV ordered from eslapion (this one will be a challenge to install, as the PLA and Processor are so close, it is impossible to insert an IC removal tool).
Thanks!!!
Vincent
Help needed to fix my C64 - rare KU-14194HB
Help needed to fix my C64 - rare KU-14194HB
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Re: Help needed to fix my C64 - rare KU-14194HB
The prime candidate...
I suspect you'll have to consider a Saruman-64 for the faulty DRAM.I also have the PLAnkton EV ordered from eslapion (this one will be a challenge to install, as the PLA and Processor are so close, it is impossible to insert an IC removal tool).
Removing the PLA is easy with a small flat screwdriver. Lift each end a little bit at a time and you'll get there.
Very nice to have thermal imaging. Quite impressive.
Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires. -John Steinbeck
Re: Help needed to fix my C64 - rare KU-14194HB
Thank you, eslapion!
Re: Help needed to fix my C64 - rare KU-14194HB
Actually, I was mistaken, it's not a memory chip at the bottom, it is the Hex inverter, the HD7406P, so I guess it is normal that it is warm. It has the right voltages.
I'll wait for the PLA and for the VIC-II chips to see if it changes anything.
Vincent
I'll wait for the PLA and for the VIC-II chips to see if it changes anything.
Vincent
Re: Help needed to fix my C64 - rare KU-14194HB
Considering where it is relative to the CIA, I am quite sure the hot chip is U9 and it is a DRAM IC.
Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires. -John Steinbeck
Re: Help needed to fix my C64 - rare KU-14194HB
What is that hot spot near the Cartridge port? Is it just a really hot resistor, if so check its resistance, if not maybe it is a corroded trace shorting something out or making not good contact.
Just a quick tip: Have you checked the voltages on the chips already and/or if possible looked at the signals such as the data lines or other clock signals to make sure non of them are stuck at 5V or GND
Just a quick tip: Have you checked the voltages on the chips already and/or if possible looked at the signals such as the data lines or other clock signals to make sure non of them are stuck at 5V or GND
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