GM5(x5x5) not working, is the chip dead?

[sineSurfer]

Hi everyone, after moving all my gear to my new studio room I was about to do all the MIDI wiring and found out that one of my gm5x5x5 is not recognised by the computer now.

 

So, I went thru some steps:

 

Change usb cable

Change usb hub port

Connect GM5x5x5 direct to computer

Reflow some suspicious spots on the pcb

Reflow every pin in the GM5 chip

 

But no luck, is it possible that the chip itself may be dead?

 

 

This is how it looks when the racks are plugged into the usb hub without power, I guess all five output leds turn on to indicate this:

 

 

When the usb hub is powered the leds go off, both racks do this,so, ¿ everything is working ok at this point?

 

One detail:

 

When plugging the faulty GM5x5x5 to the usb hub, a led in the hub flashes 4, 4 and 2 times before going off, all the other led ports just stay on while something is plugged

 

A GM5 chip closeup, everything seems to be fine:

 

What should I test?

Is there a way to check if the GM5 chip is dead?

 

 

Thanks!

 

 

 

 

 

[nILS]

What does the gm5's main LED do?

[sineSurfer]

Hi nILS, it stays off all the time, something wrong in the pcb power traces maybe?

[nILS]

It completely staying off is a bad sign. 

 

1) Make sure the jumpers are set correctly

2) Check the voltages

3) Is the EEPROM mounted?

[Altitude]

..

3) Is the EEPROM mounted?

 

Out of curiosity, why is that important?

[nILS]

Because in an old revision the silkscreen was the wrong way around, making this a pretty common error (eeprom wrong way round = nothing worky)

[sineSurfer]

hiya!

 

 

1) Make sure the jumpers are set correctly <- they are

2) Check the voltages <- will do, but... where to start?

3) Is the EEPROM mounted? <- the socket is mounted (reverse way) but no EEPROM as I just went with the jumpers thing to differentiate each gm5

 

 

Thanks!

[nILS]

2) Check the voltages on the inverter sockets (pins 7 + 14). If  they're all good, trace a +5V and Gnd track/plane to the pins of the gm5 (following this pdf)