The Workbench

Re: LX2502 Sound but no picture

blong — Sun, 19 Apr 2009 04:13:29 GMT

Hi = My Guru, BJ 'Baz' Hunter, has passed on the following info: B+O introduced a mod for the Lx2502 concerning field collapse.

It is: If the Vertical Output chip has to be replaced (TDA2170 no longer available), replace with TDA8172 and Adaptor PCB and change 4R78 to 3.3k and 4R85 to 0R56 = Brian (N)

Re: LX2502 Sound but no picture

blong — Thu, 16 Apr 2009 14:33:10 GMT

More to think about = If it does turn out to be loss of field scan, the next test is to check for 24 volts between pins 4 and 10 of IC2 (the vertical output chip). If the 24 volts is missing, you would need to check the supply circuit which comes off the LOPT at pins 12 and 4 - two diodes (D39 and D40), two safety resistors (R74 and R75) and the two electrolytics (C44 and C45). I'm assuming you have a multi-meter and know how to use it! It can get very interesting - and frustrating!! Let us know how you get on = Brian (Northumberland)

Re: LX2502 Sound but no picture

blong — Thu, 16 Apr 2009 13:58:02 GMT

Yes, as Onyx has indicated - turn the lower of the two pots (not the Focus one) clockwise little by little - if it is loss of vertical drive, you will see a bright line across centre of screen, but first mark the position of the pot so you can put it back! I am assuming that you can recognise the LIne Output Transformer, as this is what we refer to. Let us know what happens - good luck = Brian (Northumberland)

Re: LX2502 Sound but no picture

onyx — Thu, 16 Apr 2009 13:22:46 GMT

hi,

try to rotate (just a little) the G2 regulation pot and watch to the screen if something appear...

Re: LX2502 Sound but no picture

blong — Thu, 16 Apr 2009 10:45:19 GMT

The white flash you get at switch off - does it look like a line across the screen centre the split second you see it? If so, it's probably field collapse ie no vertical scan (I'm assuming this set is a CRT type - will have a look when I get a minute) = Brian (Northumberland)

Re: LX2502 Sound but no picture

Craig — Tue, 03 Feb 2009 13:46:27 GMT

Premiumverum:

Did you already check http://www.repairfaq.org/sam/tvfaq.htm ?

Great website with lots of info on fixing TV's, symptom oriented. Has been a great help for me! (and I learned a lot from it!)

Thanks for the link, I wil have good look through it later. Welcome to Beoworld BTW.

Craig

Re: LX2502 Sound but no picture

Premiumverum — Mon, 02 Feb 2009 13:26:17 GMT

Did you already check http://www.repairfaq.org/sam/tvfaq.htm ?

Great website with lots of info on fixing TV's, symptom oriented. Has been a great help for me! (and I learned a lot from it!)

Re: LX2502 Sound but no picture

Craig — Sun, 01 Feb 2009 07:32:15 GMT

Die_Bogener:

Could be a bad cap in the tuner section or AV switch...

Hmmm, check it with the AV port, connect a VCR or DVD player.

Both the RF connection and AV port are the same.

Craig

Re: LX2502 Sound but no picture

Die_Bogener — Sun, 01 Feb 2009 03:54:37 GMT

Could be a bad cap in the tuner section or AV switch...

Hmmm, check it with the AV port, connect a VCR or DVD player.

Re: LX2502 Sound but no picture

Xseries — Sun, 01 Feb 2009 02:34:39 GMT

1. Service Manual

2. Try a hair dryer to warm some of the components on the first couple of boards. It is usually capacitors that cause the problems.

3. Be careful

4. Keep the external good parts and buy another TV for next to nothing and make 1 good from 2 bad!

LX2502 Sound but no picture

Craig — Sat, 31 Jan 2009 15:35:18 GMT

Just collected a faulty LX2502 today, the problem is there is no picture only sound. Really I only brought it as it came with a working BL1000. Well the TV is in mint condition so I thought I would take a look. When I removed the back and switched it on the end of the tube is glowing as it should. When you turn it off you get the white flash in the middle of the screen. So I assume I have power to the screen. Does anyone have any idea where to look next?

Craig