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Sunday, July 25, 2010

My droid sounds like a 1930 Ford Model 'A'

After an entire weekend of wiring and rewiring R2's electronics, I'm starting to realize that one of the components has a major problem. The vmusic2 sound module seems to be the weak link because instead of playing the R2 sounds, it sounds like an obnoxious noisy engine.

It's frustrating because there are only 17 days until Celebration V and this droid must be fully operational by then. To remove these new electronics and rewire the old back is my last resort. But it's beginning to look like that's going to be my only option unless I can figure out what I did wrong or find out the cause and then find a suitable replacement component.

Normally things like this don't rattle me but when you have a hard deadline it can drive you crazy. I tested the amplifier independently and it works just fine. My guess is the vmusic2 module is the bad guy.

4 comments:

Stan said...

That sounds like motor boating.
It could be due to interference emi rfi or it could be due to bad power. It is hard to advise but I would say here are a few suggestions to check assuming you checked the wiring many times and it is correct.
(These are not a priority order just things you could try)
1) Use a shielded cable for audio between your vmusic2 and your amp,and make the connections short.
2) Take the power (pos and neg)from your battery directly to your Vmusic2 and amp (not sharing with other circuit boards)
3) add some capacitors on the vmusic2 and amp power lines to pos and neg (0.1uF and 1000uF)
4) unplug the input to the amp is the noise still there? volume turned up? down?
5) take R2 out of the garage away from florescent lights or refrigerators etc does noise go away.
6) power the amp and vmusic2 from a different battery with nothing else on R2 turned on.
7) check the ground connections. are short.
8) put the amplifier and\or vmusic2 (inc connections)in a metal box together be careful not to short anything.
9) do a search for something like amplifier motor boating
10) check the voltage is correct at the amplifier and vmusic2
Disclaimer I never used vmusic2 before but I have heard this type of noise before. If all the above does not help track it down try putting the output from the vmusic2 into another amp.

FloridaRobot said...

Thanks for all the tips to help me track down this noise Stan. And you're right. It's more like a boat.

If I unplug the input to the (4) amp, the noise is gone. If I then plug that input into my laptop headphone port, the music plays fine out of the amplifier.

The vmusic2 is wired into the JEDI controller board so I can't power it separately but I'll look into trying some of the other suggestions.

Thanks !

Stan said...

If you cannot separate the power between the Jedi controller and the vmusic2 then try running the power to the Jedi controller separately from the amp, the grounds (battery neg) should come from only one place (the battery) same for the pos (if they are using the same voltage)
try not to daisy chain them from one board to another,

Are there any servos moving back and forth when you start all this up?

I have numerous suggestions to try but...
If your show that you want to go to is the 12thAugust then you may need to make the decision to go back to your old setup.
Most of my suggestions would take time to try out correctly.
motor boating is sort of a technical term. (not just my term). Motor boating sort of happens to amps when the power supply can not handle things well. I think this is some sort of interaction interference.
Sorry, I wish I could help out more. Good luck with your deadline

FloridaRobot said...

Stan, I haven't posted this in a blog yet but I recently talked to the developer of the JEDI board and I also talked to a few others who have the same symptoms and problems.

The unfortunate thing I discovered was my VMUSIC2 modules are fried. And it's the amps that are causing all the problems. I found one guy who has an older amp (he bought about 15 years ago) and it works fine. So I ordered one of those which should resolve all problems. Unfortunately it's big so I'll have to be creative to squeeze it in.

So it seems the problem was happening between the VMUSIC2 and amp.

Thanks again for your great input Stan. Greatly appreciated. Jim