I do some hobby repairs mainly of my own junk, and I don't know much programming level repair/mods.
I got the AVR-2802 over the weekend, sold as working of course, and it worked for 1 night, using EXT. IN 5.1CH jacks, then after power down, the audio never came back. I've reset it, and get nothing on EXT IN or PHONO, despite having everything set right, hooked up right. I can hear lots of relays work tho.
I just want it for 5.1CH analog inputs , for PC surround sound. I'm not worried about the video or most of the digital stuff for now.
So far I've traced the audio into the latch and volume controller IC's, but it doesn't get out of the volume controller's.
Looking at the timing in the datasheets for the volume controllers, I can read the volume level setting for any volume I set, with an oscilloscope. But the spacing of the signal, IDK if it's right. Sometimes there's big gaps in the clock in one place, other times there's a gap in the clock elsewhere. Gap's of a few cycles.
When I line up the CLK and DATA, I see the dB level codes in the 1st 16bits. But then bit 24 should be a "0" bit as they write in the pdf, but on the scope it keeps being high.
But if I'm reading the data write, the "Volume select data" A/B/C (in TC9482), all get set low, so none of the audio gets passed. I have no idea why it can't or won't turn on the outputs. IDK if some other condition is blocking it.
I also see the clock stay high for a few times longer than it normally does. IDK if that's typical, or a problem with the MCU.
The MCU is the TMP88CU74F, besides some 100R resistors and connectors, the volume data comes direct from it. And there's no ROM chip on that PCB, so any program and memory is probably internal.
Any idea's what to do next to see if the MCU really works ? Otherwise I'll just have to bypass the volume control from the MCU, with something I'd try to write for ardinuo.
Right now I took PCB's out, to find the MCU.
Picture 41 show the clock in yellow, GRN is data, blue is strobe. You can see the clock staying high for longer than it does other times, IDK if that's normal or a sign the chip has a problem. Maybe it's internal ROM is dying, and the A/B/C data is lost ???
For now, since the volume IC is just a voltage divider for the signal, I'll just make some dividers and wire them in place of the 2 volume chips, and see if that works. Or rather than remove the chips, cut some traces to bypass the chips. See if that works, I never tried applying a signal past those chips yet.
I got the AVR-2802 over the weekend, sold as working of course, and it worked for 1 night, using EXT. IN 5.1CH jacks, then after power down, the audio never came back. I've reset it, and get nothing on EXT IN or PHONO, despite having everything set right, hooked up right. I can hear lots of relays work tho.
I just want it for 5.1CH analog inputs , for PC surround sound. I'm not worried about the video or most of the digital stuff for now.
So far I've traced the audio into the latch and volume controller IC's, but it doesn't get out of the volume controller's.
Looking at the timing in the datasheets for the volume controllers, I can read the volume level setting for any volume I set, with an oscilloscope. But the spacing of the signal, IDK if it's right. Sometimes there's big gaps in the clock in one place, other times there's a gap in the clock elsewhere. Gap's of a few cycles.
When I line up the CLK and DATA, I see the dB level codes in the 1st 16bits. But then bit 24 should be a "0" bit as they write in the pdf, but on the scope it keeps being high.
But if I'm reading the data write, the "Volume select data" A/B/C (in TC9482), all get set low, so none of the audio gets passed. I have no idea why it can't or won't turn on the outputs. IDK if some other condition is blocking it.
I also see the clock stay high for a few times longer than it normally does. IDK if that's typical, or a problem with the MCU.
The MCU is the TMP88CU74F, besides some 100R resistors and connectors, the volume data comes direct from it. And there's no ROM chip on that PCB, so any program and memory is probably internal.
Any idea's what to do next to see if the MCU really works ? Otherwise I'll just have to bypass the volume control from the MCU, with something I'd try to write for ardinuo.
Right now I took PCB's out, to find the MCU.
Picture 41 show the clock in yellow, GRN is data, blue is strobe. You can see the clock staying high for longer than it does other times, IDK if that's normal or a sign the chip has a problem. Maybe it's internal ROM is dying, and the A/B/C data is lost ???
For now, since the volume IC is just a voltage divider for the signal, I'll just make some dividers and wire them in place of the 2 volume chips, and see if that works. Or rather than remove the chips, cut some traces to bypass the chips. See if that works, I never tried applying a signal past those chips yet.
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