Sony KDL-37S550 - bad image - not gamma chip but same effect

[noledud]

Sony KDL-37S550

Hi all got the above and after seeing the image i thought it was gamma chip on tcon - ( i didnt check just sent the board for repair )

when it came back the fault was still there so my guy replaced the gamma chip again and he said it definitely tests good however i still have the fault

my question is is there anything else that can fail on the tcon to cause this or could it even be the main ? or worse the panel ?

My guy who replaces the gamma chip says there is another on the buffer that could be at fault ?

[budm]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

You should take the DC Voltage of the GAMMA Voltage test points on the T-CON to se if they are normal or not. Your on screen user menu seems to look normal though.

[tom66]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

My guy who replaces the gamma chip says there is another on the buffer that could be at fault ?

I am not aware of any second chip.

The fault looks identical to any gamma issue. I can't think of anything else that can cause it. The menus are two-tone, so maybe they don't show the effect well?

It is possible the guy had a bad gamma chip twice. There are quite a few bad ones. Did you ask if he checked gamma voltages? Because that is really the only way to test it.

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Well I have just received another tcon and same issue so I doubt it's 3 different ones well 2 but replaced the gamma chip twice so in fact 4 tcon shave been tested

What would you look at next ?

I've tried gamma chips another tcon, moved all cables and freeze spray can't get the picture to change at all.

[tom66]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

But have you tested the gamma voltages?
That will tell you for sure.
If you don't know how, post a picture of the T-con board.
A surprising number of T-con boards are DOA with this fault.

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

hi all

ok im checking voltages now here are what i have on the full replacement TCON from fleebay (GRR or GRR_Price_attack)

1 - 15.43
2 - 15.18
3 -
4 - 12.56
5 -
6 - 10.81
7 -
8 - 10.12
9 -
10 -
11 - 7.75
12 - 6.81
13 - 7.02
14 -
15 - 4.90
16 -
17 - 4.26
18 -
19 - 2.94
20 -
21 - 0.55
22 - 0.31

Now i cant find all the test point unless its me being blind - i have attached 2 pics if anyone can point out the rest

but even with the missing results from what i have there is at least 1 spike so thats a bad gamma chip then i guess

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Here is the original tcon that first had the fault and since had 2 gamma chips

1 - 15.34
2 - 14.94
3 -
4 - 12.73
5 -
6 - 10.85
7 -
8 - 9.91
9 -
10 - 7.95
11 - 7.59
12 - 6.51
13 - 6.88
14 -
15 - 3.13
16 -
17 - 3.12
18 -
19 - 3.12
20 -
21 - 3.12
22 - 0.29

But while testing the points i caught the gamma chip and it sparked and burnt a hole in it now white screen ( it just gets better ! )

When i first sent him the board he said he found some resistors with low values so he replaced them as well

My theory is gamma chip burnt out / went bad as they do on these tcons

i bought the set and sent the tcon for gamma chip when he also replaced "some resistors"

I received it back and fault still there so sent it back to him to redo he sent it back again with another chip still tested bad - this is when he said it must be the buffer ?

so i started the thread - after seeing tom agreed with me and its most likley gamma i decided to order another tcon

then i was just unfortunate to receive DOA

im thinking replacing the gamma on the new tcon should resolve does the above sound about right to you guys also ?

[tom66]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Yes, that seems right.
Replacing the chip, I found it was very difficult and I had to do it twice, had an overblown image both times.

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

thanks tom , its turning into one of those TV's £10 here £15 there its creeping up not had any for a while then this so swings and roundabouts

[tom66]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

It is why I suggest replacing it yourself if you have the ability. No telling what the guy does, or if he tests his work.

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

It's the equipment I've got no hot hair station, do I need a uber expensive one or will a cheap ebay job do the trick ?

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Got the 2 tcons back

tried the first one last night ( ebay one tested bad gamma chip )

fault still there

didnt have time to check voltages but will post later after work

now my guy who replaces the gamma chips has never sent me a dud befor i got this set

i cant belive that all have been bad and done incorrectly, there must be something else effecting the picture and also the voltages on the tcon as i bet when i check later they will be out

now im thinking its the main as that feeds the tcon but what do you think ?

[flocko]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Hi Do all the T.con boards show the same bar code number ? the one shown in post 6 shows the part number (bar code) 5537T04C29 and is for the T315HW02 V7 panel your panel sticker shows it to be a T315HW02 V8 it could be a compatibility problem that you have Flocko

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Hi Do all the T.con boards show the same bar code number ? the one shown in post 6 shows the part number (bar code) 5537T04C29 and is for the T315HW02 V7 panel your panel sticker shows it to be a T315HW02 V8 it could be a compatibility problem that you have Flocko

It might be slightly different but should still be ok to use, however i have the original that was fitted in the TV and that gamma chip has been replaced but that also still has the fault

im really thinking main board but can that make the voltages read bad on the gamma ic ?

[tom66]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

No, a bad main board cannot cause the gamma voltages to read low on Sony LCD. Only Sharp LCD lets you adjust gamma voltages from service menu.

I suppose there's the modicum of a chance that it's panel related - but I really doubt it, as after seeing hundreds of gamma chip faults, they have all been fixed by a new AS15 or AS19 IC.

There isn't really anything more to suggest -- bad gamma voltages ultimately means something is wrong on the T-con and 99.9% of the time it'll be the gamma IC... the 0.1% is other odd faults but I would not even know where to start with those.

[Andrew F. Ali]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Other important T-con typical dc voltages include:
1. vin (vcc) 5V or 12V
2. vdd (vlogic, vddd) 3.3V
3. vda (vs, vsource, vdda, avdd) 14V-20V
4. vgh (vgon, von, vddg) 20v-30v
5. vgl (vgoff, voff, veeg) 5V-7V
All five (5) dc voltages must be present on the T-con board for it to work properly.

Upon further investigation it was noted that there are a lot of cheaper chinese AS15 and AS19 Gamma chips on the market and that they aren't reliable. So your Tech and you by extension could be a victim of these cheaper unreliable chips.
My suggestion is to replace the T-con board all together.

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

iv have done that, so i have 2 tcons both had bad gamma voltages so replaced gamma chips ( on of them has been done 3 times with differnt chip suppliers )

but i still have the fault, to be the gamma chip on both and after a few replacments the odds would be massive

has any one got a set that i could send them the tcons to test ? that way i rule them and the panel out ?

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

also will know more when i get new voltages tonight when home

[noledud]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

hi all update tried the origianl tcon ( the one that has now had 3 gamma replacments )

ITS WORKING

so this is down to my tech doing the gamma chip incorrectly the first 2 times

can some on give me a list of items / tools i need to buy so i can replace these my self ? as im not wanting to trust someone else again

Cheers

[tom66]

Re: Sony KDL-37S550 - bad image - not gamma chip but same effect

Hmm. Or the chip was bad.

I use a hot air gun to take them off... I believe you can get a decent one for about £70.

Solder, flux, wick and a steady hand to put them on again.