Help Reading Sony Schematic

I've narrowed down the problem on my TV, but I need some help reading a schematic. What do solid black arrows with values next to them pointing to inputs/outputs mean? There are no units (V, Ohms etc.)beside them, so I'm assuming they are DC volts?

I'm pretty sure that the main speaker amplifier is defective, but before I go through the process of ordering another one, I would like to confirm that the supply voltage is present. On the IC it shows a value of 21.5 with a solid black arrow pointing to VCC, can I assume that I should have a reading 21.5 VDC at this pin?

Reply to
Degull
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That would be my assumption, in a properly functioning circuit. Check for general notes on the schematic, i.e. ' all values shown in DC volts unless specified '.

Reply to
Michael Ware

Reply to
Bennett Price

Those are voltages and are DC. There will also "TP"s on these boards that are test points for crucial voltages. Could you give a more extensive description of your problem? What's the model #? Is there no sound at all? Is it tuning properly? Is there sound on the line outputs? There is a common problem with Sonys of a certain type where the sound just goes out or gets really flakey but the line output is unaffected. Look for "Sony KV-32TS35 No Audio" in this same forum, posted Dec 30. I actually had one like that and bought the part from Mats. Works fine. Very satisfying. Richard

Reply to
spudnuty

The TV is a Sony KV-32TS35. The video works fine but there is no audio. I tested the audio outputs at the rear of the TV with a pair of computer speakers and they work fine. I have been using a schematic for a Sony KV-27TS35. The audio and tuning sections in the KV-27TS35 look identical to what I have in my KV-32TS35. After following the audio path in the schematics it looks as though the audio is split to two areas once it is processed in the SBX1637 sound module. The SBX1637 feeds the audio outputs at the rear of the TV on the A board and the main speaker amp on the B board. I'm assuming that because I have audio at the audio output on the rear of the TV, the audio output of the SBX1637 must be good. I checked the voltages on the main amp which is a TDA2009A chip and they all match the values on the schematic except the for the outputs of the chip which are 0 VDC (they should be 10.7). It looked as though the TDA2009A chip was bad. So I managed to find the TDA2009A at local electronic supply (the only one they had) and I replaced it. Damn it, still no audio? The new chip tested the same as the original chip with all the voltages matching the schematic except for the outputs which were still 0 VDC. I'm wondering if I got a bad chip? It was the electronic store's last TDA2009A.

I read somewhere that I should be able to test the inputs of the main amp IC by using a pair of amplified computer speakers? This will tell me if the audio signal is reaching the amp IC (TDA2009A). The inputs of the amp IC read 1.4 VDC as shown in the schematic but I'm not sure that means that audio is present.

I thought I had it licked with a new TDA2009A, but I guess not.

Reply to
Degull

Sounds like maybe the internal speakers are in the OFF postion in the Menu,s. Did you check the Menu,s ?

Reply to
kip

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