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

[PCS_]

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

It appears d705 is shorted! All the rest show ok

I repair a lot of retro consoles like mega drive, SNES, n64 etc and I'm also now trying to get into repairing Sinclair's

[PCS_]

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

Oh and I love gaming especially on the retro's

[stj]

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

sinclair's are a bastard, the output isnt true pal.
some monitors will work, others will give a dark or unsync'd picture.
i'm experimenting with one to get a decent composite output.

the best test monitor is the philips cm8833-mk2 originally sold for use with amiga's

i use one on consoles, arcade games etc.
it's only 14" though.

[stj]

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

It appears d705 is shorted! All the rest show ok

i just noticed it has a 5r parallel resistor - i hope you lifted one end and re-tested!

[PCS_]

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

Ok that was definitely a schoolboy error on my part. That diode is fine!

I'll have to see about getting hold of a Philips for test purposes. Would sit nicely on my bench. Just like a big tv for gaming on. I'm the same with modern consoles.

[stj]

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

i'll tell you what - i bet this would interest you!
http://www.sintron-hk.com/GBS-8220-a...-P2699965.aspx

[PCS_]

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

i'll tell you what - i bet this would interest you!
http://www.sintron-hk.com/GBS-8220-a...-P2699965.aspx

I have been thinking about getting a converter like that, great little things

I've just lifted L704. How would I test the driver chip? I'm used to testing components on a smaller scale, ie 5v circuits lol

[stj]

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

just power the tv up and see if it still flashes an error - dont expect a picture!

[PCS_]

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

Still doing the same. Can hear high pitched noise and the thump when tube tries to come on

[stj]

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

right, start looking at the psu section for something shorted on the outputs

[Alastair E]

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

Frame-timebase issue.....?

[PCS_]

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

Hi Alastair. How would I check that?
I'm trying to work out the best way to discharge the big power caps so I can meter up components. Want to check the HOT to see where things stand there too

[R_J]

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

Did you check the +200 volts on the crt board? If its there that eliminates a lot.
You should have +135 volts on the collector of the h.o.t. If it is there, check for posible shorted diodes around the flyback transformer. D536 & D539 gave problems on similar chassis.
if the high voltage does come up for a sec. then I would think the power supply and horz. output are o.k.
There are +15 and -15 volts that come from the flyback and supply the vertical o/p ic see if they are there (the test points are marked on the board)
Just a few things to try

[PCS_]

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

Did you check the +200 volts on the crt board? If its there that eliminates a lot.
You should have +135 volts on the collector of the h.o.t. If it is there, check for posible shorted diodes around the flyback transformer. D536 & D539 gave problems on similar chassis.
if the high voltage does come up for a sec. then I would think the power supply and horz. output are o.k.
There are +15 and -15 volts that come from the flyback and supply the vertical o/p ic see if they are there (the test points are marked on the board)
Just a few things to try

Thanks for that, very helpful indeed. Its all a learning curve for me. I'm attempting to eliminate all the tests that can be done with the set in a discharged state. I'm not used to working with HV caps that are full of charge yet. I'm fine with discharging the anode.

Any tips or tricks of the trade would be appreciated because I doubt you wait for everything to self discharge before testing resistance. im quite safety conscious.

[stj]

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

get a few high voltage resistors, 470k or higher and solder them in series - put wires on each end and stick it in a plastic tube like a bic pen body.

you can discharge anything other than the tube wih that.
the reason you solder several inline is to prevent an arc between the ends.

[PCS_]

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

That's a great idea, but what about insulating the wires to the cap or is that not necessary? Also what sort of gauge wire are we talking?

I've got a pack of assorted resistors 1/4 watt carbon film type as that's what I use but I don't think they will handle high voltage will they?

[stj]

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

cap???

high voltage resistors are usually gray, not the usual light-brown carbon or light-blue metal film.
wire guage is not important because the discharge current is very low - insulation is important - it must handle what your using it for.
so 500v is a good number.

if you look at good psu's they often have a high voltage resistor across the mains cap to discharge it.
maybe you can salvage a few from some scrap boards.

the other thing, you can check caps with your volt meter before and after you discharge them - you may be surprised just how many dont stay charged anyway.
they discharge through the load.

[freakaftr8]

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

what he means by retro computers are like some of the older Apple Macintosh PCs used Trinitron CRT's and also some Atari amigas I believed use the same as well as Trinitrons of the old school era built ega style for some of the old IBM PCs with the EGA cards

[PCS_]

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

cap???

high voltage resistors are usually gray, not the usual light-brown carbon or light-blue metal film.
wire guage is not important because the discharge current is very low - insulation is important - it must handle what your using it for.
so 500v is a good number.

if you look at good psu's they often have a high voltage resistor across the mains cap to discharge it.
maybe you can salvage a few from some scrap boards.

the other thing, you can check caps with your volt meter before and after you discharge them - you may be surprised just how many dont stay charged anyway.

they discharge through the load.

By cap end I meant not using just wires but possibly meter probes?

500v I don't think I've got anything rated for that!

I wasn't sure about testing big caps with a standard multimeter either as My father had a special high voltage meter that he used regularly for tv work. I do have several PS3 psu' from fattys so maybe there's sometjing in those that I can use, never really had them to bits as I just swap them out if they become faulty

[stj]

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

most meters can do 600v dc
i cant see you going close to that as long as your not trying to check the voltages on the crt.