Pentranic chassis screen jumps
- Thread starter Retroman839
- Start date
Retroman839
Senior Member
Yes I will take a pic when home
Yes I thought about why I do not have that supply line attached to the vertical ic also..
I do not know where my supply line is comming from now .. but I am getting the symtoms that are discribed as in relation to flyback supply
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Retroman839
Senior Member
D506 is spanning them 3 traces in the middle
Black sharpie marks are me
Just marking location
i can't really see from the photos but i am sure you have the tracing of d506 wrong, to me it looks like cathode goes to jumper 9 and then you should have c333 intalled
the anode of d506 should go to pin 3 of the transfomer in the supply section - imagine that would have been done by an extra wire linking them
Here is what I would do, add the correct diode to d506, install correct cap at c333, run a wire from anode of d506 to pin 3 of the supply transformer, dummy load the collector of the HOT, measure voltage at c333, once correct voltage is seen then do the rick mod BUT i think you will also need this supply to go to the vertical ic
the anode of d506 should go to pin 3 of the transfomer in the supply section - imagine that would have been done by an extra wire linking them
Here is what I would do, add the correct diode to d506, install correct cap at c333, run a wire from anode of d506 to pin 3 of the supply transformer, dummy load the collector of the HOT, measure voltage at c333, once correct voltage is seen then do the rick mod BUT i think you will also need this supply to go to the vertical ic
Retroman839
Senior Member
Cheers
I will look to find the pin 3 of transformer
C333 is in place yes
Seems though as 2 x resistors either side of d506 are also missing
I will look to find the pin 3 of transformer
C333 is in place yes
Seems though as 2 x resistors either side of d506 are also missing
Retroman839
Senior Member
I will get set up to do dummy load test also
Remove middle leg of hot ..
Test all power side is working .
Remove middle leg of hot ..
Test all power side is working .
Retroman839
Senior Member
Ah ok I will take a look in a bit ..
Guess I’m missing a few componamts then
Guess I’m missing a few componamts then
Retroman839
Senior Member
power supply must still be comming from flyback though because it’s jumpimg when screen is white out..
Só maybe supply to the transformer is from flyback ?
Só maybe supply to the transformer is from flyback ?
you are losing me, the transformer is in the power supply circuit - it provides the b+ for the flyback, on your chassis the flyback provides the voltage for the ic but the mod is the supply transformer to supply the ic voltage, if you were to do as i said and add the diode and cap and then read the voltage on the cathode to see if you get a stable correct level
Retroman839
Senior Member
Yep lost my self too .
I’m lost as to where it is getting power at the moment with this circuit unpopulated .. because it works but screen jumps .
Not sure why I thought I had that cap ..
just to confirm although you now I don’t have it
Empty c333
Socket and j9 noted
does this missing circuit share the b+ ?
I need to get a cap & diode
Then …
I will have a look a schimatic .. for the particular values on them two parts and source ..
I might have a diode I can pull off some spare parts
I’m lost as to where it is getting power at the moment with this circuit unpopulated .. because it works but screen jumps .
Not sure why I thought I had that cap ..
just to confirm although you now I don’t have it
Empty c333
Socket and j9 noted
does this missing circuit share the b+ ?
I need to get a cap & diode
Then …
I will have a look a schimatic .. for the particular values on them two parts and source ..
I might have a diode I can pull off some spare parts
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Retroman839
Senior Member
Lookimg
For 680 ohm
First one I tried ?
This ok ?
that was just luck
Retroman839
Senior Member
Can i pull a diodeCan i Measure a diode
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Retroman839
Senior Member
Fast recovery 3A
Orderd thanks grant 👍
Im sure i have that cap
Will be back once i got them ready to go
I will swap the 680 ohm resistor in with leg remaining out of circuit with jumper wire solderd on ..
Fit cap
Fit diode with cathode leg out of the chassis and solderd to jumper wire to 680 ohm resistor ..
Once
Done i will pop up a picture just Só you can check it..
Then maybe do a dummy load to check volts ?
( 18v to vcc of vertical oscilator )
Orderd thanks grant 👍
Im sure i have that cap
Will be back once i got them ready to go
I will swap the 680 ohm resistor in with leg remaining out of circuit with jumper wire solderd on ..
Fit cap
Fit diode with cathode leg out of the chassis and solderd to jumper wire to 680 ohm resistor ..
Once
Done i will pop up a picture just Só you can check it..
Then maybe do a dummy load to check volts ?
( 18v to vcc of vertical oscilator )
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Retroman839
Senior Member
Só just install everything as it should be & test
what i would do,
install diode and cap, leave everything else as is for time being
test voltage at cathode of d506, if all is good install resistor r318 and link to pad of cathode - i think there is a through hole marked B you can use for the wire
install diode and cap, leave everything else as is for time being
test voltage at cathode of d506, if all is good install resistor r318 and link to pad of cathode - i think there is a through hole marked B you can use for the wire
without this in front of me its so difficult to see the multiple mods you can do, i think you will also need to link the anode side of the diode to pin 3 of the supply transformer. you can see through hole for wire jumps all over this chassis