Any new findings on this board?
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Yes sorry everyone I've been very busy with this board. I'm doing my best to prove my theory wrong. I'll have something by the end of the day tomorrow.Any new findings on this board?










I like how cell phone cameras traditionally make everything look better except closeups of solder lol8H at N2 Pin 14.
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4H at P2 Pin 11.
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2H at P2 Pin 12.
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1H at P2 Pin 13.
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6 MHz at P2 Pin 14.... Yikes
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6 MHz at 6MHz test point on the PCB.
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12 MHz at the 12 MHZ test post on the PCB.
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Someone has been here before and it wasn't me.
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Yup. Broken solder joint on C1 and C2. I had mentioned to you previously, the cabinet was being stored in an outdoor building by the previous owner. Look at the rust on the crystal can. Hopefully the crystal within is still in its spec. I'll clean everything up next weekend as I've run out of time. I'm going to take the time to do some out of circuit testing.I like how cell phone cameras traditionally make everything look better except closeups of solder lol
this is one of those instances where I would take everything apart there and redo it, making sure that everything is connecting to where it should
256H is a digital clock signal generated by dividing the input clock signal through the three LS163A counter ICs (P2,N2,M2). The CRT retrace time has nothing to do with its generation. 256H should be on for 256 clock cycles and off for 256 clock cycles.256h may not be a signal with 50/50 duty cycle normally, when that line comes on, you're in horizontal retrace which isn't as long as drawing a line. Due to this, 128h should also be off more than it's on.
Your 6mhz and everything after looks fine. If it was a borderline clock you'd have intermittent sync issues and instability.
Yeah, in a prior reply I told him where the issue was for a previous repair with the exact symptoms he is having. He could have saved himself a ton of time by going into the area I mentioned. If he doesn't have a comparator, piggyback the less than 10 ICs in that area with known good ones, with the scope on the output pins of the ICs, looking for any signals that go into contention.You're barking up the wrong tree.
Yeah, in a prior reply I told him where the issue was for a previous repair with the exact symptoms he is having. He could have saved himself a ton of time by going into the area I mentioned. If he doesn't have a comparator, piggyback the less than 10 ICs in that area with known good ones, with the scope on the output pins of the ICs, looking for any signals that go into contention.
If 256h is supposed to be 50/50 duty cycle, then explain this.
That's 256h on my working board.
256 won't be 50/50 because the timer circuit is not set to count to an multiple of 256 because of retrace. It counts 256 for the drawn area, then a bit more after the hsync pulse to wait for retrace.
Nah. The problem is that trevor used generic probes that weren't calibrated. Even so, who knows when that scope was calibrated last! If it's like mine, it would have been 20 years ago!Your problem is you're using a Hantek scope instead of a Rigol.