Core issues

[matt_kronik]

I am working on building a core per rasteri's Scratch Wheel project.  I'm having trouble uploading MIOS to my core and I'm not sure where the breakdown is happening.  My operating system is Windows Vista (spare me your sarcasm) and I'm connecting it to my laptop via an M-Audio Uno USB to MIDI interface.

I assembled my core and plugged in a power source before installing the opto-coupler and PIC.  Ready to check the voltages per "Constructing a MIDIbox Core Module from a SmashTV Kit" by Jim Henry, I noticed that the 7805 voltage regulator was abnormally hot.  I quickly unplugged my power source and found that it was not putting out said values (7.5v @ 500mA was 16v @ 250mA).  I bought a new power source, hooked it up, and got 5 volts at the points as instructed, unplugged the power source, and installed the PIC and the opto-coupler.  I do not have an LCD screen, so I skipped that step.

I connected my MIDI interface per "MIOS Bootstrap Loader for Newbies" and got no upload request from the Core.

I proceeded to the the "MIDI Interface Troubleshooting" page:

TEST PROG1: I have no idea how to do this step, nor can I find any info on how to do it.

TEST CORE1: I have a 10Hz crystal connected in the correct location.

TEST CORE2: I don't believe this is relevant for a SmashTV Core kit.

TEST CORE3: Looks good.

TEST CORE4: Get 7.1 volts on all locations.

TEST CORE5: Get same 7.1 volts on all locations.

TEST CORE6: Polarity is correct.

TEST CORE7: Diode band is in the right direction.

TEST CORE8: R8 and R7 are both 220 ohm.

TEST CORE9: Double checked cross connection.

TEST CORE10: No request messages.

TEST OUT1: LED does nothing when on M- and M+, but will turn on (possibly flickering faster than I can see) when connected to M- and middle pin and M+ and middle pin.

That's as far as I got, before getting really frustrated.  >:(

I know this group is real helpful, so thanks in advance everyone!

[matyt]

7.1 Volts?!

It's extremely high.... I fear you may have fried the 7805... and maybe also the pic....

[stryd_one]

Totally. I wouldn't be powering on with chips until that's fixed.

Did it read that high when you tested it without the chips?

[matt_kronik]

It did not in fact read that high without the chips.  When I bought a new power source, it read 5v (4.98v to be exact).  The values didn't change until after I plugged the chips in.

If I fried my voltage regulator, as matyt suggested, then I learned the hard way and it's no big deal.  If I fried the PIC, then I'm friggin' heartbroken :-[.

Also, I wanted to know how to complete TEST PROG1 of the troubleshooting, page.  How would I do this?  Is it part of the MIOS development suite?

[stryd_one]

It would be very strange for the vreg to output 5V, and you tested 5V at all points on the board, then you insert a couple of IC's, and it starts outputting >7V. Weird. What did you read after removing the chips again? 5V again? or still 7?

The fear here is that the fried vreg will have output too high a voltage and subsequently fried the pic. Hopefully not, but time will tell.

As for TEST_PROG1... Did you program the chip yourself? Or was it preburned from mike/smash? If that's the case, then it is OK, and you can continue with the other tests.

Anyway, you should not be doing those tests yet. First you need to sort out this voltage problem. You can't do those tests without the chips, and the chips should not be inserted yet.

[matt_kronik]

I'll get to work on that soon, stryd_one.  I've kinda put the whole thing on hiatus until I get some other major things in order outside of this project: car, money, employment, etc.

[stryd_one]

Good luck! :)

[matt_kronik]

Hello again, guys.

  So after a long hiatus, I did some surfing through the troubleshooting forum.  I have reason to believe that my voltmeter is no longer reliable.  I tested the output of the new power source I purchased, and they all test about +3 volts over what they should.  I went about checking various voltages: mobile phone battery, laptop power source, and old laptop power source. I found them all to be about +3 volts over what they're rated at.  I think I can get a hold of a better voltmeter with out spending any money, but that'll take some time.

I looked at test core section again and found that polarity of my MIDI ports was reversed! Great success!

Tried the core again, but still got nothing.  However, it's a step in the right direction.

I'll get some pics of my box up in the "scratch controller" topic up really soon.

[nILS]

While power supplies can put out a different and usually higher voltage w/o load a battery really doesn't do that, so I guess - get a new meter. They aren't really expensive at all. I paid 10EUR for mine a while back and it works like a charm.