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Trying to fix a universal 25-29 china chassis (SOLVED)
perjmolsen:
Hi
Thanks for your help.
I have tested the resistors behind the ribbon cable they are fine.
If I try to measure volts at the resistors, and the chassis as ground I have 0 volts.
My fuses are good, also my two BU2508 is good.
I have to figure out what delivers my heater volts, do you have a schematics that are close to my chassis?
princess prin prin:
Heater is most likely from the flyback. Just follow the trace from pin 9 or 10 of the CRT socket back to the main chassis and you'll see where it goes.
perjmolsen:
Hi
I have now found a A59 tube :applaud: it is from a Panasonic 25" inch TV
When i do the yoke readings i get the following
VR: Blue - brown: 5.5 ohms
HR: Red - White: 1.7 ohms
And my chassis sticker says
VR: 9.6 ohm
HR: 1.3 ohm
The vertial is a bit lower on the monitor, and the horizontal is a bit higer but do you think that would be OK? it is a A59 tube.
So would it be worth a try to connect the china chassis to the tube and see if I get any luck with neck glow and maybe picture on the screen ;D
perjmolsen:
Hi
An update
I have now connected the chassis to the monitor, when I turn it on i got a vertical collapse, so it seems that the chassis works with the crt
BUT something stange is also - when I connect the input from the game pcb to the chassis, and turn it on the circuit breaker in my room triggers.....??!
I will try to change the D1138 (NPN Power amplifier Vertical deflection) newer changed, I had previously order sone new but newer received them, so I have order some new today
and also the LA7840 (Vertical IC) again, to see if that fixes the issue.
grantspain:
needs to run on an iso transformer
the vertical impedance is very low for a cga chassis but it should sort of work