Troubleshooting midibox core

[John_W._Couvillon]

Need Help!

In my organ midification project, I have installed two cores (id 00 and 01) running midio128 software.  Core #00 has 128 inputs (note on/note off) to encode to organ manuals of 61 notes each.  Core #01  merges with midi input on core #00 and is also a midio 128 with  96 inputs of a possible 128, and this core serves the pedal board ( 32 notes on and off)  the last 32 inputs (also note on/note off) provides for stop input . I do not have LCD's installed.  I use the virtual software jorgan.

Power supply for the two cores comes from a typical radioshack plug-in hockey puck that provides 9 vdc to the J1 (power inputs) connector  of both cores.  The 9vdc power module plugs in to a 120volt duplex receptacle in the console that serves also a fluo. fixture over the pedal board. The receptacle is wired through an on - off switch on the

front of the console with a heavy lamp cord and typical ac plug. 

The organ console had to be moved to a new location which had been done, With the console in its new location and with the complete console/computer setup connected together,midi cable connected,  computer on with midiox running,  and the ac plug at the console in the wall receptacle, the fluo. light did not come on.  The on-off switch on the console had no effect.  I wiggled the plug in the ac  120 vac wall outler and created a short in the plug with subsequent flash, crash and circuit breaker trip on the outlet circuit.  Needless to say, the plug was fried, so I cut off the plug, installed a new plug and plugged it into the wall outlet.

The on-off switch worked, the fluo. light came on, and I glanced over to the computer monitor for inputs on midiox, to show the response from the core, and there was none.

I rechecked all connections, etc., but found nothing.  With power on to the 9vdc module, I checked voltages on the J2  (5 vdc) connector and on the  J1 connector (10+ vdc) and  voltage was present, but still no midiout to the computer.  I thought for sure that the fault had fried the dc supplies or the rectifier or 7805 reg. chip, but all seem to be ok. Both cores have rectifiers and 7805 regulators.

The PIC is an 18F452 (kit from smashtv which has functioned flawlessly for the last year or so).  Is it possible that the fault sent a spike through the cores that messed up the programming but the PIC is still good?  Is there a way to confirm wether the PIC is fried or still good?  Or should I just buy two new cores and start over again.

Any suggestions will be a big help. 

Regards,

Johnc

[TK.]

Hi Johnc,

beside of the most comfortable solution to buy two new PICs, you could try to do some measurings first.

Which instruments do you own - analog meter, digital meter, scope?

Which voltages do you read at following pins:

RD7 - pin #30, LCD enable line - it should toggle very fast ca. 2 seconds after startup for ca. 500 mS, until MIOS notices that no LCD is connected

RD4 - pin #27, port J14 - should be 0V, if you read another value, then it is very likely that the bootstrap loader hasn't been started

Tx - pin #25, the MIDI Out pin - should be 5V, if not, the BSL hasn't been started

Best Regards, Thorsten.

[John_W._Couvillon]

Hello Thorsten,

I have a small digital multimeter for measuring voltages which I used at the points you described:

1.  RD7 - pin #30, LCD enable line - it should toggle very fast ca. 2 seconds after startup for ca. 500 mS, until MIOS notices that no LCD is connected -the voltage measured a steady 4.5 millivolts dc.

2.  RD4 - pin #27, port J14 - should be 0V, if you read another value, then it is very likely that the bootstrap loader hasn't been started - J14 measured 11.2 millivolts dc.

3.  Tx - pin #25, the MIDI Out pin - should be 5V, if not, the BSL hasn't been started - pin#25 measured 5vdc

Regards,

Johnc