Had this set come in, it did need a cord, but it needed other things. I am not sure if we put a fly in it, but that sounds right. I had pulled the chassis out and was unaware that the ribbon cable had pulled off the CRT socket board.
Well, the set was hooked to a grounded antenna and not in isolation. When they crimp those wires into the plug, the ends are bare. I can attest to this because it touched the heatsink of the standby chopper, which is on the primary side.
There are alot of grounds in this thing and luckily all it blew out was a buffer stage coming out of IX400 IIRC, the TDA9330H. I repaired the problem, it had not fried the whole board, I had to replace a transistor and resistor in the final buffer stage to the CRT boards, I got the red back. It was working. (IV400 ?)
Whatever it is, it is a TDA9330H, and is now not putting out H drive. I KNOW this board worked, I KNOW because there is evidence of my repair to the red channel. Yet now there is no H drive.
I checked all Vccs, inputs to the stages between the 12Mhz and the scan frequency. This chip does not have shutdown, except by bus control. Now a somewhat logical assumption could be that the chip got zapped that day and still worked for a little while. The red output was indeed hit with the negative side AC rectified while grounded. (isolation was running another set at the time, I thought it would be OK, dummy huh)
I distinctly remember fixing the red channel, I did, I remember distinctly that I at least corrected the problem I created. This could only happen if the board works. Right ? It did, I know it did, I swear it did.
Now there is no H drive, which comes out of the same IC. Think I "shocked" the IC into failing ?
There is one other possibility, RCA did not use this, but there is a bit in the I2C you can set to disable Hdrive. What are the chances that the OS is screwed up and it will simply set the same bit in a new IC to the same state ?
Thanks.
JURB