liquidx
New member
Hi,
I have a tron that's basically producing noise/thumps/clicks instead of sound. Running the channel test gives me these cracks and thumps on all 6 channels. All the usual things were done, switch AY3s, check voltages, new ribbon cables etc.
Anyway, after moving around with a logic probe I noticed that when I touched the ground pin on the LM3900 with it I could hear the sounds faintly, so I guessed I might have a grounding problem. And, indeed, when I jumper the ground pin (7) to the board ground I get all the proper sounds and music.
Looking at the schematics I see there's a separate ground for the analog/audio section which is connected via the amp board down to the 12V output of the isolation transformer. I checked this for continuity and it looks ok.
So, my hack works but it's obviously not the way things are supposed to be as I'm basically connecting 2 grounds that were designed to remain separate.
Not sure where to go from here apart from the capacitors but I must be missing something.
By the way, this problem exists both with the original power supply and a switcher adapter.
Thanks
I have a tron that's basically producing noise/thumps/clicks instead of sound. Running the channel test gives me these cracks and thumps on all 6 channels. All the usual things were done, switch AY3s, check voltages, new ribbon cables etc.
Anyway, after moving around with a logic probe I noticed that when I touched the ground pin on the LM3900 with it I could hear the sounds faintly, so I guessed I might have a grounding problem. And, indeed, when I jumper the ground pin (7) to the board ground I get all the proper sounds and music.
Looking at the schematics I see there's a separate ground for the analog/audio section which is connected via the amp board down to the 12V output of the isolation transformer. I checked this for continuity and it looks ok.
So, my hack works but it's obviously not the way things are supposed to be as I'm basically connecting 2 grounds that were designed to remain separate.
Not sure where to go from here apart from the capacitors but I must be missing something.
By the way, this problem exists both with the original power supply and a switcher adapter.
Thanks