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Trying to fix a universal 25-29 china chassis (SOLVED)
princess prin prin:
The big 3.3K resistor (orange/orange/red).
And pin 2 of the flyback, not 3 and of course the lightbulb needs to be connected to the trace not to the pin itself. Or desolder the HOT and connect the bulb to the middle pad (in this case you don't have to lift the resistor).
Is that isolated or an autotransformer?
PL1:
The "Pin3 flyback" photo above appears to show a tiny glob of solder shorting the pin 4 and pin 9 traces below pin 4 and some residue on/near several solder joints that looks like flux.
It would be a good idea to clean those areas with some isopropyl alcohol and a Q-tip. :cheers:
Scott
grantspain:
i would like to add that the flybacks used on these chinese clone chassis are pretty rubbish, i had a weiya clone less than a year old come in for repair with flyback bad- cheaper to buy a replacement chassis
perjmolsen:
--- Quote from: princess prin prin on January 11, 2019, 02:35:02 pm ---The big 3.3K resistor (orange/orange/red).
And pin 2 of the flyback, not 3 and of course the lightbulb needs to be connected to the trace not to the pin itself. Or desolder the HOT and connect the bulb to the middle pad (in this case you don't have to lift the resistor).
Is that isolated or an autotransformer?
--- End quote ---
Hi
Oh yes pin 2 ;) a typo and a drawing error from my side.
I have removed the one leg of the big 3.3K resistor
One wire from the 40W bulb to pad of pin2
And i have 115.4V at the pad - I assume that is good :)
Note that the D1138 is not put in yet.
About the transformer, i do not know if that is an isolated or autotransformer... it only says step up or down transformer and it gives 110V at one outlet and 220V at another.
Any conserns?
What to test next? I assume some low volts ex at LA7840 at pin 6 - datasheet says recommended 24V
Another thing...
The best monitor for this chassis - I guess that i should be one as close to the vertical and horizontal ohms reading.
Chassis:
VR: 9.6 ohm VL: 24.6mH
HR: 1.3 ohm VL: 1.5mH
I got a monitor with this reading
VR: 12.9 ohm (yellow -green)
HR: 2.1 ohm (red-blue)
I guess that is to high - for best compatibility is is best to be under og over?
Thanks again :cheers:
perjmolsen:
--- Quote from: PL1 on January 11, 2019, 03:11:31 pm ---The "Pin3 flyback" photo above appears to show a tiny glob of solder shorting the pin 4 and pin 9 traces below pin 4 and some residue on/near several solder joints that looks like flux.
It would be a good idea to clean those areas with some isopropyl alcohol and a Q-tip. :cheers:
Scott
--- End quote ---
Hi Scott
Thanks for the notice :)
I have now removed it :cheers: