Sanyo DP32746 poor audio

[thor2015]

I posted about a week ago on this TV but I have a new problem so I thought I would start a new thread with a relevant title.

I received this TV from a friend. She said the TV would not turn on. I plugged it in and sure enough it was unresponsive. I cracked it open and found that one of the 200 volt caps on the power supply was bulging so I ordered the replacement caps and installed them. I also found that on that same circuit path was an unsoldered lead (solder joint was hollow and pin was sitting in the middle). I resoldered that pin and the TV now turns on. However, it has a new problem.

When the TV is first turned on, the audio is loud and clear. After about 10 or 15 seconds something sounding like a fan (although I have not yet been able to locate one in the TV) comes on. When that happens, the audio diminishes slightly and begins to clip/distort. Also, if one of the volume buttons on the side panel of the TV is pressed there is a loud pop that comes through the speakers.

I am unable to locate any other bulging or leaking capacitors and all other solder joints look good. This TV has separate power supply/video/audio boards. I made sure when replacing capacitors to replace them with the same capacitance and voltage ratings and exceeded the ripple current ratings. None of the zener diodes on the power supply measure shorted either.

Another interesting note- I repaired another TV of a different brand a few months ago and the person I got it from said that the first time it died and the power supply board was repaired the audio was very poor. Upon my repairing it for the second time I noticed the same thing. Is there a common part on these power supply boards that would fail alongside the bad caps to cause this audio issue?

Thanks in advance for any help you guys can offer.

[randtek]

Re: Sanyo DP32746 poor audio

It sounds like you still may have some bad capacitors. Just because they are not bulged or leaking does not mean they are good. I would try to check or replace all of the power supply electrolytics, not just the obviously bad ones.

[thor2015]

Re: Sanyo DP32746 poor audio

Thanks for the reply. Is there a certain section of the power supply board I should be looking at that powers the audio? I have 24V, 13V, 6V and 5V test points just at a first glance. Some other threads I have been reading on other Sanyo TV's with sound issues suggest that the 13V powers the audio. I'd like if possible to narrow it down a bit and take a logical approach rather than a "replace until it is fixed" approach if that makes any sense.

Once again, thank you for responding.

[budm]

Re: Sanyo DP32746 poor audio

The 13V is for the ClassD power amplifier IC. Does this TV has RCA Audio line out jacks (RED/WHITE). Do you get the distorted sound at the line out also?
Pictures of the boards?

[thor2015]

Re: Sanyo DP32746 poor audio

Bud,
I will try that tomorrow and let you know- it does have RCA outputs. I did try HDMI input as well as regular component cables and got the same result from both ports so I know it isn't a specific input port or cable issue. Also, will try to get some pictures of the boards uploaded as well.

[budm]

Re: Sanyo DP32746 poor audio

If that is the case, both HDMI and the RCA analog line out are bad, that will eliminate the power amp problem as least, which will lead to the audio processor chip or bad DC feeding it.