The manual states that R425 is a fusible 100 ohm 0.25W resistor. There are a couple of this type of resistors around the board, with different resistance- and power ratings. They are mounted around 15 mm above the circuit board.
I thought this should be mentioned to avoid any injury... (Not...
Hmmm .... I thought that these boards would have the same article number. Except maybe the last digit which is the revision number.
The mxc-chip is different (probably only the way it is mounted to the board) but board layout is identical. Also I've read on multiple places that robocop and bad...
First I have to correct myself. Each tile is 8*8 bits. Every rom has two bitplanes making the tile 8*8*2=128 bit... Just like mr tendril said :)
... And now it's time for the grand finale.
I've been scouting for a bac06-chip for a long time.
I found a non-working heavy barrel in a terrible...
Chances are slim that it is the exact same transistor.
I'm certainly no expert but a good start to check this circuit would include transistors Q107-Q112 and diodes d101-d105.
Also try to see if some resistors look burned. When a resistor overheats it loses some of its resistance.
I am happy to announce that my chassi is fixed. I measured resistance to ground and could conclude that there was a short.
With the schematics as a guide I desoldered part after part to cut off the problem area. Finally I had narrowed it down to a few parts and traces and used magnifying glass...
Brightness turned up to max. Measure on the pot's middle leg and the leg closest to where the input from the jamma-harness goes.
Please try to switch red and black and note if the resistance changes (due to diodes)
Yesterday I connected my other two chassis to the very same monitor. B+ was measured at fuse 802 and the ground pin named P4.
I got 112,5 volt on the glued one and 112 V on the other chassi. None of them had a too dark picture!
At least we can confirm that the problem is within the chassi...
So tube is tested OK ... This is really strange. I get perfect picture of if I turn up B+ to 118 V. Making me suspect that i measure it at the wrong place.
Since my first attempt I have come over two extra pm1723c so I'll try to hook them up and check their voltages. The b+ pot is glued from...
Back from the test bench... When applying 24 volt with plus on banded side the coil draws as supposed to. When applying 24 volt with plus on unbanded side I get a short.
I suppose the diodes are working but just cannot be measured the usual way.
Edit: this was such a stupid thread so I deleted it as much as I could.
Moral of story: When measuring a diode use diode test and preferably out of circuit.