Sony Trinitron KD-28DL10U red, green, red, green OCP fault

[PCS_]

Hi guys,

I've been given this Trinitron, it was working fine 2 months back, has just been sitting in a spare bedroom since.

I powered it on yesterday to find that it won't come on, just gives the OCP error on the LED.

Any advice on where to start? Someone has said that the jungle chip could be the cause but I want to rule out bad caps and transistors before I go down that route

I will obviously ensure I discharge the high voltage to tube

Thanks

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

have you got a schematic?

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

Thanks for your reply stj, Yes I've got the service manual with schematic
I've linked to it below for your reference,

Thanks

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

http://www.maisiemanuals.com/sony/so...l-p-17519.html

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

so explain in detail what happens.

on page 41, is the neck board.
there are 3 testpoints: TP4-6
with the tv off and unplugged, check to see if any of these testpoints are shorted to any other pins on the tube socket.

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

I press the power button, tube sounds like it is energised. Ie the noise a CRT usually makes when you turn it on but no picture it just goes off and gives blink code

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

well those testpoints should not show any low resistance to the other pins on the socket.
if one does, unplug the board from the tube neck and check again.

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

Yes I see, TP 4-6 of J701 thanks

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

So this will give an indication of the troublesome circuit I presume? I need to clear space on my bench for this as its a fairly chunky set, once I do I'll post back my findings from the continuity test.

Is this the point to always start at with CRT's with this problem? Reason I ask Is to understand how you've pointed towards the C board. Sorry for all the questions but Im keen to learn.

Thx

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

i'v never worked a sony wide,
but ocp on philips and thompson is common - unfortunatly there is a reliability problem with the tube.
it is very common for the blue gun to short and shut the tv down.

if you find one gun is shorted, there is a way to double-check,
you lift the resistor and spark-gap for the shorted gun and the tv should run with a coloured field.

now hopefully none of the guns will be shorted.

the problem is these fucking narrow necks on the modern crt's have much less space between all the parts - yes, they use less current to drive the heater and they start faster,
but at the expense of reliability.

[R_J]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

You could also check and see if you have the 200 volts to ic701, I have replaced these ic's in the past for being shorted. If the 200 volts is low or missing, disconnect pin 6 of ic701 and see if the voltage comes back up.

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

i'v never worked a sony wide,
but ocp on philips and thompson is common - unfortunatly there is a reliability problem with the tube.
it is very common for the blue gun to short and shut the tv down.

if you find one gun is shorted, there is a way to double-check,
you lift the resistor and spark-gap for the shorted gun and the tv should run with a coloured field.

now hopefully none of the guns will be shorted.

the problem is these fucking narrow necks on the modern crt's have much less space between all the parts - yes, they use less current to drive the heater and they start faster,
but at the expense of reliability.

I'm going to have to keep my fingers crossed it's not a shorted gun then. I always thought the Sony trinitrons were supposed to be an all round decent set that's what people have been telling me but then none of them have had them on a bench

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

You could also check and see if you have the 200 volts to ic701, I have replaced these ic's in the past for being shorted. If the 200 volts is low or missing, disconnect pin 6 of ic701 and see if the voltage comes back up.

It's going on my bench later today so I'll check, thanks for that

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

btw, i'm pretty sure it's not really a trinitron - those tubes need 2 focus lines from the transformer.

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

Now I'm confused. Why have they marked it as a Trinitron if it's not a true Trinitron?

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

marketing?

they pulled the same shit with "vega"
it was a flat-faced tube they licensed from russia - i have an original russian one.

but now they slap the "vega" label on lcd's - sony are scum.

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

That's absolutely discusting. the only reason I picked this set up is because I read that trinitrons are the best sets image wise for retro computers.

[PCS_]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

Right, I've got the set on bench. Checked for continuity from KR, KG and KB to the rest of the pins and none are of low resistance

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

good,
while your on the C board, check none of the diodes are shorted, then check the driver chip 701 as RJ says.
i'd isolate it by lifting L704 rather than trying to lift a chip pin btw.

[stj]

Re: Sony Trinitron KD-28DL10U red, green, red, green OCP fault

That's absolutely discusting. the only reason I picked this set up is because I read that trinitrons are the best sets image wise for retro computers.

what computers???