The Electronics Universe
Test Equipment => Oscilosopes => Topic started by: Graham361 on March 28, 2017, 12:10:18 PM
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Hi hope somebody can help I bought a yaesu monitor scope yl100 mains lead was missing so opened up today and looks like transformer has been replaced and unfinished as I now have two connector blocks the largest has wires from crt and the small one has two orange and white cables in I think this was done as transformer does not supply the these voltages I may be wrong were do I start any advice please regards graham
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Hi Graham. I will pull the schematic tomorrow and look it over . Should be fairly easy to wire it back up. Although I will say that most of the time something takes out the transformer. I would start checking all the caps on the secondary side of it.
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Many thanks for your help can you tell me the two orange and white wires that originally went on old transformer what voltage are these I know the three blue are 6.3 volt I think the orange and white are 30volt I might be wrong and you were right two cappacitors are gone 600v ones I would say someone could not get a transformer with right voltages so have done this so they need a seperate supply as they fitted two power sockets at back off unit to supply 6.3volt for crt and what ever the orange and white feed is regards graham
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This is what it's like the other side of the board mains lead cut and block added also one side of switch cut
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Thanks for those pictures. That helps. I have been extremely busy the past two days. I am off tomorrow and will see if I can get into the schematic for you.
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Many thanks regards graham
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Also found two brown wires under crt I think these also went on transformer so the two sets I am not sure of voltages they need is the two orange and white and the two brown regards graham
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The two orange and white cables go to rectifier board from transformer
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Three of the 5 capacitors were dead so changed all five these were on the rectifier board they look like they got really hot would this have caused the transformer to go u/s in the first place regards graham
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These are the six I replaced
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Today with not much experience i wired up transformers and switched it on all valves light up and crt and to my surprise have a trace on screen the vertical and horizontal work and focus but some don't function as I still have two sets of wires the two brown and the two orange and white that I am not sure of voltages regards graham
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View of board with valves and crt
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Front view with trace
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The main transformer and small transformer giving 6.3volts for crt and valve heaters