[sdiy] EFM MIDI-Gate?

[Chromatest J. Pantsmaker]

and that was the problem!

I counted the DIN pins from the wrong side.. 4 and 5 were swapped.
Now the circuit is working!

Just in time too, because I need to return this scope, they're doing
inventory soon!  :)

On Wed, Feb 24, 2010 at 8:30 PM, Jerry Gray-Eskue <jerryge at cableone.net> wrote:
>
> Ok, If you always have 5 volts on pin 6 the PIC must be supplying the pull
> up (as Grant mentioned).
> BTW the 10k is a bias resistor and works well with a 270 Ohm pull-up.
>
> My best guess is that you are not getting a good current loop on the input
> side, or the connection is reversed.
> Pin 2 of the 6n138 should go thru the 220 resistor and to pin 4 of a MIDI
> female (panel) connector.
> Pin 3 goes to pin 5 of the midi connector. NOTE: the pin out numbers of the
> MIDI connector are not in sequence, 4 and 5 are not next to each other.
> You may be able to check the loop by removing the 6n138 and put an LED in
> the socket pin 2 Anode pin 3 Cathode. It may not be very bright but should
> flash when data is received.
>
>
>
> -----Original Message-----
> From: chromatest at gmail.com [mailto:chromatest at gmail.com]On Behalf Of
> Chromatest J. Pantsmaker
> Sent: Wednesday, February 24, 2010 7:31 PM
> To: Jerry Gray-Eskue
> Cc: Synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] EFM MIDI-Gate?
>
>
> Ah.. sorry, that was old information and was indeed a problem with the
> scope.  I'm using a really nice scope now and I still can't get the
> circuit to work.
>
> It seems that I'm not getting any output on the 6n138.  I just get 5V
> and it doesn't appear to be pulsing or anything like that.  I've
> compared the schematic with the traces, and everything goes where it's
> supposed to.
>
> On Wed, Feb 24, 2010 at 6:22 PM, Jerry Gray-Eskue <jerryge at cableone.net>
> wrote:
>>  Pins 5, 6, 7, and 8 all show the same
>>> waveform which doesn't seem right to me at all.
>>
>> According to the schematic You should have +5v on 8 and Ground on 5.
>> Check your power supply, and be suspicious of your o-scope software, as
>> several people recently pointed out the sound card inputs are usually AC
>> coupled and so cannot see DC voltages.
>>
>> Use a Voltmeter or DVM (if you have one) to check out the DC voltages.
>>
>> Also the Input side of the opto should have a floating ground relative to
>> the rest of the circuit.
>>
>> -----Original Message-----
>> From: synth-diy-bounces at dropmix.xs4all.nl
>> [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Chromatest J.
>> Pantsmaker
>> Sent: Wednesday, February 24, 2010 5:52 PM
>> To: Dave Kendall
>> Cc: Synth DIY
>> Subject: Re: [sdiy] EFM MIDI-Gate?
>>
>>
>> I'm still working on this thing, haven't figured out what's wrong yet.
>>
>> I bought a stack of 10 6n138 optocouplers from mouser.  I've tried
>> several now with the same results each time.  I'm wearing a ground
>> strap.
>>
>> So, using the scope, I'm seeing 5V data bouncing on the inputs of the
>> 6n138 (pins 2 and 3) but on the output, I'm just getting a slightly
>> fuzzy +V and the scope says that it's detecting DC voltage on that
>> pin.
>>
>> I've pulled out every other IC (all socketed) and the results are the
> same.
>>
>> Thoughts?
>>
>> The Schematic is here:
>> http://chromatest.net/EFMmidi-gate.pdf
>>
>
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-- 
.sig
-Chromatest J. Pantsmaker
http://www.chromatest.net