Samsung LE37R87BD ghosting temporary image retention

[andyturbo]

Taken voltages of tcon vgamma test points results are :-
1=15.42 2= 15.28. 3= 13.51. 4=12.33. 5=11.47. 6=10.86. 7=10.51. 8=10.21. 9=9.95. 10=7.56. 11=7.38. 12=6.88. 13=6.99. 14=8.42. 15=8.60. 16=8.83 17=9.68. 18=9.44. 19=9.79 20=10.31. 21=11.80. 22=11.95

Not sure if voltages are correct or where to find them , any help would be welcome.

[tom66]

Re: Samsung LE37R87BD ghosting temporary image retention

The voltages are bad, replace the AS15-F IC.

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Thanks for help. Will follow up on outcome.

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Changed t-con board, image retention and ghosting gone, but fine vertical lines on display and colour not perfect. Running at present to see if any change. Have double checked tabs to panel and pins to tcon board. Changed caps on PSU cm 860,852 & 870 all bad, all other caps on PSU checked and OK. Wondered if another component may have been affected by caps and tcon faults possibly main board. Attached photo of display at present, showing fine vertical lines.

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Tcon test now reads v

From 1 - 22
1.57 1.66 2.96 3.80 4.35 4.86 5.10 7.20 5.50 6.10 7.33 6.92 6.78 5.08 4.86 6.80 4.28 3.86 3.44 2.82 1.36 0.85

[Shinju]

Re: Samsung LE37R87BD ghosting temporary image retention

Enter the Service menu and run the test patterns to see if its T-con or Mainboard. Power off the unit, hit Mute 1,8,2 and power on the unit.

Find the test patterns and run them. If you are unsure take some photos of the menu and someone will help direct you.

Were the lines there before the replaced t-con?

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Thanks for reply, will try test patterns as suggested. Lines were not there before changing tcon board.

[Shinju]

Re: Samsung LE37R87BD ghosting temporary image retention

Cool, the test pattern menu should have 4 or 8 or 10 options depending on your firmware. again if unsure snap a photo and post it.

for example like this.


FBE - full t-con/Mainboard processing
Logic - CPU ( I think)
READ Post PATT is mainboard only
READ Pre PATT T-con Only.

FRCS DDR patterns I am not sure, I could never get them to show up even on a working panel (might be firmware support?)

[tom66]

Re: Samsung LE37R87BD ghosting temporary image retention

Tcon test now reads v

From 1 - 22
1.57 1.66 2.96 3.80 4.35 4.86 5.10 7.20 5.50 6.10 7.33 6.92 6.78 5.08 4.86 6.80 4.28 3.86 3.44 2.82 1.36 0.85

This set of gamma voltages is still bad.

[Shinju]

Re: Samsung LE37R87BD ghosting temporary image retention

^ This man knows his stuff Did you get that board off ebay used? Send it back!

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Yes, got tcon from eBay site, will send back and get replacement. What should the test points read, so that I can test future boards. Many thanks for all your help will up date when new board arrives.

[tom66]

Re: Samsung LE37R87BD ghosting temporary image retention

A general rule of thumb: They should go up or down, one direction. (Monotonic.)

e.g.:
1V, 2V, 4V, 5V, 8V, 10V is OK
and
9V, 8V, 5V, 3V, 2V, 1V is OK.

but:
1V, 5V, 3V, 9V, 8V, 4V is BAD.

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Many thanks tom66 invaluable info. Just ordered another tcon, not from eBay, will update on outcome. Once again many thanks for replies.

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Update:
2nd replacement tcon board arrived today. Fitted and perfect picture. Run for 2 hours now and all seems fine. So problem was tcon also changed caps CB 852, CM860 & CM 870 all showing less than 25% of uF.
Many thanks for posts an info.

[tom66]

Re: Samsung LE37R87BD ghosting temporary image retention

For future reference, could you post the VGAMA voltages on your new board?

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Yes, no problem will post asap.

[andyturbo]

Re: Samsung LE37R87BD ghosting temporary image retention

Tom. Vgama Voltages of new tcon board


1 - 22
15.40 15.26 13.48 12.30 11.44 10.84 10.48 10.18 9.92 7.54 7.36 6.86 6.72 4.88 4.64 4.35 4.02 3.55 3.13 3.06 1.64 0.30

[tom66]

Re: Samsung LE37R87BD ghosting temporary image retention

Thanks, useful info, you can see the big difference.