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initial setup problem

gamma3, gamma24 (plug-in for the γ3)

initial setup problem

Postby Mercator » March 24th, 2019, 10:06 am

Hi AMB,
I've been working on and off on my Gamma 3 for a few years, taking time out to build a house among other things. So I was excited to finally finish a few weeks ago. All of the initial tests went OK. The LCduino came to life, every thing seemed fine so I started building the cases and putting the boards in final place. But now when I power up I get a very odd voltage reading to the LCDuino. I have 5 volts coming from the power supply to the molex connector for J12 but from there on to LJ4 I only get 1.247V. So my voltage has dropped to 1/4. I can't figure out why. There seems to be a strait connection from J12 to LJ4 with nothing but a cap connected to it so I can't see where the power is going. Any hints for where to look for the problem is much appreciated.
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Re: initial setup problem

Postby amb » March 24th, 2019, 2:45 pm

Are you using the proper ground reference when measuring? For LVDD, you should use the “Ground” as pictured at the γ1 website instructions section, not “Isolated ground”.

Check to make sure nothing on the backplane board is shorting to the chassis, except “Ground” via the metal plating around the mounting hole next to J12, which connects to the chassis through the metal standoff.

Make sure your J12 Molex connector pins are making proper contact.

Check to make sure C43 is installed in the proper orientation.

While you’re at it, check your DC umbilical cord connections too.

Is anything getting hot? Such as the “always on” σ11 heatsinks, or the LVDD power wires.
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Re: initial setup problem

Postby Mercator » April 11th, 2019, 5:45 am

I finally found the problem. As you thought it was in the umbilical. I some how switched the 5V and G on the always on sigma11. As soon as I reversed those everything worked fine. Now music is coming out.
So far I've built a CK2III, a beta22, beta24, and an alpha10. This was the most complex build I've done and I almost got out without any major issues. I made a few mistakes, mainly putting a couple of the small ICs in the wrong place, but I was lucky to find those before power got applied. It's a bit embarrassing to have one crossed wire trip me up. Thanks for all of these projects. Both the building and the listening have given me hours of pleasure (along with a few hours of frustration and a large amount of education). Looking forward to whatever is next.
Thanks
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Re: initial setup problem

Postby amb » April 11th, 2019, 12:22 pm

Great! I’m glad it’s all sorted now, happy listening! :)
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