Hi Kai Klaas:

Kai Klaas said check led connections or resolder. Still have not completed drawing schematic to unit, but this is what I found out about ir leds. I kept reading up ir leds on google which did help. First I changed the 330uf 16v to new 330uf 25v to make sure the capacitor was not causing problem. I also changed out the 1n4007 diode. At 20 yrs. old that would be easy, but now I am 70 yrs. old Eye sight and not steady hands big problem. This did not help clear problem with leds. I remembered I had ir tester I purchased 20yrs. ago I found it and checked ir leds for transmission. I should mention when I turn SHP22ir on the leds glow red with out a signal from tv set. So I though the leds were off when they did not have red glow when on. The ir tester showed they were on but with almost no power. This tester shows with ir led on bright green led on tester on at 6" from test. With this transmitter on only shows bright green at 1/4" from 6 ir leds. So 6 ir leds are not fully on but leads are not open either. From what I read these leds are 850nm because they have red glow when working correctly. So have some type of low level short on circuit board, but I have not found it yet. The ta2008 that works almost like the TSH512 circuit you told me about but without all the bells. I also found out that 850nm and other ir leds can cause I damage if they to close to your eyes. I always though it was like regular led as far as safety. The way this transmitter may work when turn on is the ta2008 pin 6 goes to R6 6820 ohm to base of Q2 out the collector to 3.3 ohm R14 to anode ir diode and emitter goes back base of Q4 and emitter at ground through small smd cap out the collector to the cathode of ir diode. This is for one group of three leds. The other 3 leds work the same way. What I need to know is how this ta2008 works with its pin out but have know information on google on this 8 pin chip. I will have go thought each smd component on this transmitter. If they test ok then I can maybe fix this transmitter without the ta2008 documents. Also I had to order new test leads for my meter because they slip off the smd parts. I need needle probe leads. So far the only information I have on ta2008 is it works at 5v and some pins show 2.2v. And pin 6 appears to be at ground. I should mention 78L05 appears to be working 12v in and 5v out. Without schematic or block diagram this is not worth a techs time to repair. The whole unit board is only 2"x 1 1/2" with 40 or more smd parts. I order some 850nm leds so when I get them I will try bread board circuit using values of componets that mention without using ta2008 and see how the ir leds light. Forgot to mention all 4 transistors are npn type in smd.

Best regards,

Ralph Sac