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Pi2Jamma Display Corruption

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John Bennett View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 13 Mar 2019 at 7:38am
Hmm. Well, power-wise, it’s
ATX -> JAMMA - > Pi2JAMMA -> Pi

So it’s as if the PI has pulled too much power, which isn’t the case.

The speaker is OK in the cab? I hadn’t appreciated that it’s a little power audio amp on the Pi2JAMMA (enough for an arcade speaker).

What did you do when you were getting the screenshots before to stop it smoking, or had it burnt out all it could by then?

All I can think is that there’s a bad connection somewhere or the audio amp/speaker is bad, but just early ideas.

http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 13 Mar 2019 at 11:21pm
Yes the speaker is OK. I only took those photos yesterday... when the first Pi was damaged it was approx 7 seconds before I could cut the power. Second time round about 2 seconds, and the display corruption wasn't as bad.

It still seems to me that somehow the Pi2JAMMA had driven 5V through some of the GPIO pins, but I found this post on the Raspberry Pi forums. The OP refers to WiringPi which can apparently check the GPIO pins.

I ran it on my Pi, expecting it to report faults. But no... Confused


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Digimon Quote  Post ReplyReply Direct Link To This Post Posted: 14 Mar 2019 at 6:21am
the Problem is the ATX.

It has no regulation and to much power for the pi

Just try a typical arcade switching power supply..


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Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 14 Mar 2019 at 7:11am
Ah, I hadn’t realised it wasn’t a wide-range voltage input to the PI (strict 5V) and it seems you bypass protection if you power it via the GPIO header and not the USB.
So the above suggestion to change PSUs is good one.
All funny sort of things could happen if on-board regulators misbehave and there’s external circuitry.
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 14 Mar 2019 at 10:48pm
But this problem first happened when everything was in the cab, connected to an arcade switching PSU.

Although as I said in my first post, it was at 5.5V - maybe feeding that through the GPIO was too much. 

As for the ATX PSU, I'd used that setup for testing several times before and that never happened.
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