intergrated tcon board ic rt6939 vestel polaroid p55up0277a

[jimbofz]

this tv has working psu b/light and sound with dark blue screen ,
no on screen graphics the t con is part of the tab bonding boards .
the ics used to produce the various dc supplies are :
RT 6939 and RT 6935.
.i have 12v going to board ,but need to know what pin is the enable pin on these ics
because these ics are not switched on i get no 3.3v vone voff 1.8v ect
ive spent hours looking for data on these ics
ive checked all the mlcc caps for short or low res to deck ,diodes ect
ive tried to search for details of the panel in case it included details of the tab bonding boards, no luck
does anyone have circuit or data sheet for these ics please?
i also removed the bevel to see if there was evidence of spillage or corrosion
and all seems clean none of the test points for the various voltage supplies have low resistance to earth
so im convinced it could be a feed o/c or no enable volts to start up the ics missing
all supplies on the main board seem ok 3v3 ,5v
this design without separate tcon makes life very difficult you cant unplug one side then the other to help with diagnosis any ideas please

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

seems very strange nobody has posted any replies? i wont bite tee hee

[dick_barton]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

If you can post some photos of your boards and also one showing the interconnection may catch peoples attention.

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

here are some pictures pic 6 shows clearest image of the chips i need info on thanks

[nos_feratu]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

@jimbofz I've got same problem on a different TV set, Toshiba, same Vestel integrated tcon sh@t. I found one cap straight connected to 6935 which was shorted, replacing it didn't made any difference. problem is, there is no way to find values for them as there is no markings on. Actually somebody suggested the problem might be on the actual logic board as, at least in my case, the interaction with the remote is limited. basically I can get only power on/power off response. I've started a thread couple of days ago here, so keep in touch if we have any updates.

[videocentro]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

Hi.
Some questions
1 can you check the tensions on the points indicated?
2 Can you check if you have short circuits on the points indicated?
3 can you please insert a picture of the panel tag?
4 you can put a retro tv label photo please

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

@jimbofz I've got same problem on a different TV set, Toshiba, same Vestel integrated tcon sh@t. I found one cap straight connected to 6935 which was shorted, replacing it didn't made any difference. problem is, there is no way to find values for them as there is no markings on. Actually somebody suggested the problem might be on the actual logic board as, at least in my case, the interaction with the remote is limited. basically I can get only power on/power off response. I've started a thread couple of days ago here, so keep in touch if we have any updates.

thanks ,ive removed caps to test on cap meter
both esr and cap value and all ok
if you post a pic of the cap location on your tv i can tell you what the value it should be if that helps
its strange you have limited response to remote .on mine i use scart i/p as it will auto select scart (as i cant see any on screen menu) then i can set vol mute ,and go in and out of sby ect

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

Hi.
Some questions
1 can you check the tensions on the points indicated?
2 Can you check if you have short circuits on the points indicated?
3 can you please insert a picture of the panel tag?
4 you can put a retro tv label photo please

thanks for trying to help
all the following are zero volts,
vcc 3.3v, vone, voffe, 1,8v, hvydd,
hvin is ok at 12v
ive removed the 4 caps in parallel as there was a resistance of 250ohm to deck
the caps are fine they measure 22uf each ,
i then removed the coil marked 6r8
as i thaught there may be a short underneath it,but the coil is fine also .
all the other missing voltage test points are not s/c and threre is no short between them
if you look to the right of the 4 caps in parallel the next cap (same size)has 12 volts then theres two tiny components (one a cap the other black is a resistor) then theres another cap and across it i have 5volts .i think theres something o/c feeding one of the chips or possibly a enable start up volts missing

[nos_feratu]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

thanks ,ive removed caps to test on cap meter
both esr and cap value and all ok
if you post a pic of the cap location on your tv i can tell you what the value it should be if that helps
its strange you have limited response to remote .on mine i use scart i/p as it will auto select scart (as i cant see any on screen menu) then i can set vol mute ,and go in and out of sby ect

hi mate, the cap is the one marked in the picture attached. If I hook mine to an input source it will scan and autocomute on that particular input and sound will come through, however limited interaction with the remote is observed. I cannot do anything else than power on/power off. As soon as I finish setting a more suitable workshop than the floor of my living room I'll continue investigation. If you can tell me the value of the capacitor it will be great, very much appreciated.

as well I'm considering buying a logic board as it is a good candidate for failed items category

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

hi mate, the cap is the one marked in the picture attached. If I hook mine to an input source it will scan and autocomute on that particular input and sound will come through, however limited interaction with the remote is observed. I cannot do anything else than power on/power off. As soon as I finish setting a more suitable workshop than the floor of my living room I'll continue investigation. If you can tell me the value of the capacitor it will be great, very much appreciated.

as well I'm considering buying a logic board as it is a good candidate for failed items category

the component circled in yellow is not a cap its a fuse ,its confusing as it looks like a cap bur slightly bigger and grey in colour whereas the caps are usually beige ,with regards to your fault are you using the original remote control as some will opperate in/out sby ,but may not have correct codes for as example volume ,just a thaught.

[Diah]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

i use scart i/p as it will auto select scart (as i cant see any on screen menu) then i can set vol mute ,and go in and out of sby ect

i think yours set and the other threat one of same panel the issue at main boards..

same to yours idea by using scart but this time use it as out put from the tv to to other one,, to check if you can see the menu. or any channel sign.

edit.. of course yours scart cable socket should have at least output at one end.

[arizanotlari]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

Hi.

Vestel chassis have scart output (cvbs out) but this line not worked. You can not connect another tv.

I replace this ic 1 month ago but tv not worked.


Panel is faulty if backlight working.

[Diah]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

Hi.

Vestel chassis have scart output (cvbs out) but this line not worked. You can not connect another tv.

I replace this ic 1 month ago but tv not worked.


Panel is faulty if backlight working.

arizanotlari DC to DC Enable work within signal come from main boards to switch it ON.

if you have the schematic of the MB would be helpful to trace the signal source

[nos_feratu]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

the component circled in yellow is not a cap its a fuse ,its confusing as it looks like a cap bur slightly bigger and grey in colour whereas the caps are usually beige ,with regards to your fault are you using the original remote control as some will opperate in/out sby ,but may not have correct codes for as example volume ,just a thaught.

thank you for your reply, very much appreciated. So my "capacitor" is actually a fuse so it should have 0 resistance

remote is the original one, is not a replacement/universal type.

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

thank you for your reply, very much appreciated. So my "capacitor" is actually a fuse so it should have 0 resistance

remote is the original one, is not a replacement/universal type.

ok it was worth a shot ,in that case you could have a faulty main board for two reasons;

1 the problem with remote functions
2 the enable on for these ics is from the mainboard according to post from diah
he has helped me in the past and he is very knowledgeable.

[arizanotlari]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

arizanotlari DC to DC Enable work within signal come from main boards to switch it ON.

if you have the schematic of the MB would be helpful to trace the signal source

You are right. Thanks for information.

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

Hi.
Some questions
1 can you check the tensions on the points indicated?
2 Can you check if you have short circuits on the points indicated?
3 can you please insert a picture of the panel tag?
4 you can put a retro tv label photo please

after replacing removed components and checking all cap values ,i now have the following voltages on the red arrows you put on the pic ,starting from left to right 1.07v then 12v and earth across cap
next the cap below the 220 coil12v
the cap on left of 4 caps in parallel vone .25v
the cap to right of chip rt6939 12v
and finally the cap above the220 coil voffe .24v

so on the marked test points i now have:voffe .14v bad
vone .25v bad
1.8v good
3.3v good
vcc1.05v good
hvadd ov bad
hvdd 12v good .
do you have any idea how to find the enable pin for the ic ,
i assume it must go high to turn on the ic and start the vone and voffe voltages?

[budm]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

What is the resistance reading on HVADD and VONE against ground?
So now you have 1.8V, 3.3V, and 1.05V that you did not have before in post #1? What did you change?

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

What is the resistance reading on HVADD and VONE against ground?
So now you have 1.8V, 3.3V, and 1.05V that you did not have before in post #1? What did you change?

well i was concerned that there was 250ohm to deck across the 4 caps in parallel i removed them ,
same
so removed the coli marked 6r8
same
i looked at other connections at rear of panel only to find there are LINKS inside the pcb ,not just twin sided print these links appear as pin sized dots ,when i used fibre pencil on them and checked resistances between various points i found a connection that was oc
vertually impossible to see even with my head up magnifier .
also if you shine a light through the board you can just make out these links .
once i soldered the pin sized links i then ran a fine wire to make a good contact ,it makes me wonder these links are so fine that what current they could handle would be minimal.
now that i have some voltages i now have the coil 6r8 dropping .4v across it from 1.4v to 1v so im beginning now to suspect the ic

[jimbofz]

Re: intergrated tcon board ic rt6939 vestel polaroid p55up0277a

You are right. Thanks for information.

hi did you trace the source of the enable voltage from the main board? as Diah
sugested ?
ive studied the circuit and cant see where the enable comes from
can you help? thanks