Rank: Member
Groups: Member
Joined: 1/10/2018(UTC) Posts: 4  Location: Iowa
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I've been unable to get my BBB-Hermes-Cronus to function. I suspect a power problem with the cronus. To keep this as simple as possible, I have a botic 4 image from Miero and just using speaker-test. The BBB alone will output I2S with the uEnv editted to mclk = 0. So the BBB seems OK.
When hermes and cronus are connected, speaker test will not run, there's no mclk getting to the BBB, or the mlck output jack on the cronus
Last night I was probing voltages on the cronus, and noticed 2.0v across C10. Is this correct? The cap was also slightly warm. Heat may be coming from the nearby regulator?
Also downloaded some spec sheets on the ICs. There's no clock signal on the input to the divider. The crystals are putting out 49 and 45 Mhz, but I'm not sure what the clocks should look like coming right out of the crystals. They're not nice squarewaves. Is this normal?
I guess I need some test points to check out. I have a 200mhz fluke scope, voltmeters, etc... I've re-flowed the solder on the ICs, and I've looked the two boards over very carefully, with magnification, for any solder defects. Lost for ideas at this point. Please help!
Thank You,
Mike
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Rank: Member
Groups: Member
Joined: 1/10/2018(UTC) Posts: 4 Location: Iowa
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Update: Today I ran the board with the oscillators removed, and checked the Vcc to the oscillators, and found it would track the VD input voltage, so no regulation was happening. I found there was 85 ohms across C10. Pulled C10 (not the problem) From the ground pad of C10, to pin 2 of IC 5 is 135 ohms, and ground pad of c10 to pin 3 of IC 5 is 88 ohms. This is measured with the two pins of the IC lifted from the PCB. Pretty sure the regulator IC is bad. I had something like 2.7v feeding the oscillators, and both oscillators had 4.x volts on their output pins. I really don't know what happened to the cronus, it was not over-voltaged... I checked both oscillators with a scope and power supply, they seem to be fine... Looks like IC5 = ADM7154 @3.3v Guess I need another cronus or regulator. Wish I knew for sure the Hermes was OK... Edited by user Tuesday, January 23, 2018 7:41:14 PM(UTC)
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Rank: Member
Groups: Member
Joined: 4/21/2007(UTC)
Posts: 59
Location: Minnesota
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I'm sure Brian will bet back to you ASAP...
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Rank: Member
Groups: Member
Joined: 1/10/2018(UTC) Posts: 4 Location: Iowa
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They responded today, got the info I needed from TPA, and have parts ordered from digi-key!
Right now, even though the 3.3v regulator has been substituted with a bench power supply, and the IC that selects the clocks has been bypassed with a jumper wire, I have LOCK on my Buffalo II and Volumio doing the playback!
This is where I wanted to be almost two weeks ago. But, still happy to have had some success! I pretty much know the two boards inside and out now!
Thanks for your support!
-Mike
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