Pentranic chassis screen jumps

[Retroman839]

Rick has kindly supplied
A diagram


D506 … ?
Just need to fimd it then ?
Or is that a zener ?

 

[gunblade]

d506 is in power supply section

 

[Retroman839]

As he has drawn then..
Over near flyback

 

[M K L]

It's the same as my suggestion.

 

[Retroman839]

It's the same as my suggestion.

Só pull diode leg out out of circuit ?
Awg 20 -22 for the jumper wire ?

Replacement 680 ohm resister 1/2or 1/4 watt ?

As soon as home from work will look for d506
And remove resistor
Thanx

 

[Retroman839]

I got this 19” ver as well with same circuit …
Só will try to look for d506 on this as I have it with me .

This 19 does have date holes and clearly marked 18v

 

[Retroman839]

Ok ..
The plot thickens

Now with ricks digram
Gives me a good idea where the d506 lives ..

And
It’s unpopulated ?


Along with 2x resistor or jumper and a resistor missing in circuit ?

 

[gunblade]

that can't be right, d506 is straight off the supply section secondary of T501 according to the schems
is that the correct schem for the chassis?
can you take a photo of entire chassis component side

 

[M K L]

Solder side would also be helpful.

In the schematics posted earlier, the PSU only outputs two voltages, B+ (rectifier D501) and 24V (rectifier D506). In your last pics there seem to be several rectifier diodes so probably the schematics are not exactly for your chassis.

 

[Retroman839]

Variants of the chasis include a duel res

This is cga only só I don’t think the schimatic is strictly correct but closest I could
Find

 

[Retroman839]

I sent pics of unpopulated d506 to Rick also ..
See what he says too .

 

[Retroman839]

Should have a 680ohm in here

 

[Retroman839]

that can't be right, d506 is straight off the supply section secondary of T501 according to the schems
is that the correct schem for the chassis?
can you take a photo of entire chassis component side

I thought it comes of the flyback secondary ?

 

[gunblade]

no, the voltage from the flyback is what you are replacing, d506 is on an output of the power supply section transfomer
from what i can work out you replace r318 with 680 ohm and solder one side to the ic side of the original track/pad and leave the other end out of chassis, solder a wire to this leg and run wire to cathode of d506 or do the same by cutting track of r318 and run wire under chassis

 

[Retroman839]

no, the voltage from the flyback is what you are replacing, d506 is on an output of the power supply section transfomer
from what i can work out you replace r318 with 680 ohm and solder one side to the ic side of the original track/pad and leave the other end out of chassis, solder a wire to this leg and run wire to cathode of d506 or do the same by cutting track of r318 and run wire under chassis

But d506 not there ?

Só I need them to look at the transformer 18v out ?
And pick up there ?

 

[gunblade]

i think its wrong schematic otherwise you would be missing a voltage to other sections of the chassis - is there a an5521 fitted on this chassis?

 

[gunblade]

i think this is most likely your chassis

https://arcarc.xmission.com/Web%20Archives/KensKorner/Pentranic%20CH-288%20Monitor%20Schematic.pdf

 

[Retroman839]

i think its wrong schematic otherwise you would be missing a voltage to other sections of the chassis - is there a an5521 fitted on this chassis?

I will take a look for it

 

[Retroman839]

i think this is most likely your chassis

https://arcarc.xmission.com/Web%20Archives/KensKorner/Pentranic%20CH-288%20Monitor%20Schematic.pdf

Cheers grant .
Yes this is the Schimatic of my chasiss ..

18v from inductor L401 of T401..

Só I guess question is

Where to take the trace wire to instead of the d506 ?

 

[Retroman839]

Also …
If I’m not connected to flyback ..
Then the hole thing about the over voltage of screen white out causing screen jump seems out the window if I’m not connected to the flyback. ..

But screen jumping on all white / flash screen is the
Symtom Thats stopping this chasiss being fully operational .