AT-200 guitar stopped working on batteries; still works with external power?

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peanutismint
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AT-200 guitar stopped working on batteries; still works with external power?

Post by peanutismint » Tue Dec 03, 2019 5:50 pm

I have a Peavey AT-200 guitar but it no longer runs on battery power. I’m measuring the correct 6V across the battery terminals and across components on the Antares circuit board but no power light or sound output.

If I power the guitar from the external breakout box it powers on and works fine. Also, if I unplug the breakout power cable whilst the guitar is still switched on, it continues to run on the installed batteries (as it should) until I cycle the power switch, at which point it refuses to ‘start up’ again on battery power until it is connected to the external power cable again.

This has only started happening recently after about 2-3 years of it running fine on batteries. I’d like to figure out why this has stopped working.

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JamesPaul
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Re: AT-200 guitar stopped working on batteries; still works with external power?

Post by JamesPaul » Mon Dec 09, 2019 10:31 pm

I would call Peavey and get the schematic for the Antares circuit board.

It has been while since my electronics design days, but I am remembering a simple way to accomplish such switching uses diodes in series (forward biased) with the positive supply rails of both the battery and adapter. Both of the diodes' cathodes are connected to the positive of the Antares circuit. The negative supply rails are connected together and to the Antares circuit ground. The Antares circuit will then power from whichever of power sources, adapter or battery, has the higher voltage. This does rely on the adapter voltage being higher than the 6V of the batteries.

If the design is this simple, one of the diodes might have an issue.

However I would like to see the schematic first. There could also be some single component that integrates this functionality with other features. Lots of discrete circuits I remember have been combined into one silicon device these days.

Edit: Here's an example of the simple circuit. The voltage values would likely be different with the Antares circuit in place of the 100 ohm resistor.
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Example Circuit
Example Circuit
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peanutismint
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Re: AT-200 guitar stopped working on batteries; still works with external power?

Post by peanutismint » Tue Dec 10, 2019 4:43 pm

Thanks for the info. I'll try putting in a call to Peavey.

peanutismint
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Re: AT-200 guitar stopped working on batteries; still works with external power?

Post by peanutismint » Mon Oct 05, 2020 4:36 pm

Hey sorry to resurrect this post from a long time ago but my call to Peavey didn't achieve anything. They basically said they wouldn't know how to fix it and I'd have to purchase a new board at almost the entire cost of the guitar, but I haven't given up hope of getting it figured out. Here's some links to the board schematics/installation guide in case it jogs your memory on any potential issues:

PART 1: https://pdfhost.io/v/zm4V6Kn0T_ATG_Anta ... KHx_WxrBlY

PART 2: https://pdfhost.io/v/UfJaZChST_ATG_Anta ... KiGCC3ijxU

Also, having probed the board a bit more, I've found a couple of capacitors right next to each other. With both 9V mains and 4 x AA batteries installed they measure +9V and +6V respectively, but the circuit still won't turn on on battery power alone. I'd love to know if you have any reccommendations about potentially diagnosing or replacing these diodes.

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