Harlequin 48K Rev. G - First Time Power Up
Posted: Thu Dec 30, 2021 9:35 pm
Hello,
I have finished soldering all the components on the Rev. G PCB I bought of eBay.
Only the RGB video out is going to be used, so I haven't installed any of the Composite Video components. I power up the board using my lab power supply:
For the +5V line, the tester shows a constant 4.96 - 4.97 V
However, there must be something wrong with the way I assembled the components, or one or more may be faulty - irrespective of the jumper position on J12, all that is shown on the monitor is:
After removing the EEPROM and powering up, I see this:
"Reset" seems to work only sometimes - there is not always a "feedback" on the screen after shortening the two pins on J13.
I have a logic TTL tester on order, but I wonder if there is something else I could do before it arrives. Any help will be greatly appreciated.
I have finished soldering all the components on the Rev. G PCB I bought of eBay.
Only the RGB video out is going to be used, so I haven't installed any of the Composite Video components. I power up the board using my lab power supply:
For the +5V line, the tester shows a constant 4.96 - 4.97 V
However, there must be something wrong with the way I assembled the components, or one or more may be faulty - irrespective of the jumper position on J12, all that is shown on the monitor is:
After removing the EEPROM and powering up, I see this:
"Reset" seems to work only sometimes - there is not always a "feedback" on the screen after shortening the two pins on J13.
I have a logic TTL tester on order, but I wonder if there is something else I could do before it arrives. Any help will be greatly appreciated.