Mesa Road King Channel Switching + GCP + GCX

[JohnClark]

WOW!

The switching jacks simply make or break the connection between the Tip and Sleeve connection. If you have a continuity tester of some sort you can confirm this is happening. The Out/N.O. Tip to Sleeve should be open when bypassed and shorted when the loop is active.

What is the story with this GCX... Is it new or used? I wonder if it is possible that the loops have been modified to be internally connected in series rather than requiring a cable to connect the Out of one loop to the In of the next loop. Also, what kind of cables are you using to make these connections?

[blewmeaway]

The GCX unit is used, i just received it from ebay, it is an older digital music corps model. i've used all different kinds of cables thinking that this was the problem but every cable reacts the same.

However, i just tested continuity and got some rather strange results. loops 1-4 seem to be connected because if i left loop 4's cable hooked to the out jack, and the other end of the cable connected to my tester, and then proceeded to connect a cable from my amps channel switching jack to any other loop 1-3, continuity was made. These were the results only when the GCX was powered on, if it was off, there was no continuity.

If i tried the same tests with loops 5-8, there was no continuity.

This leads me to believe that the gcx been modified, however after discovering that loops 5-8 seemed to work ok, i tried channel switching via the gcp and gcx and i still had crappy results.

I'm so lost.

[JohnClark]

It seems likely that this GCX has had some things done to it that will render it useless for your needs. A new, unmolested GCX, or even a Control Switcher would clear this mess up in a snap.

[blewmeaway]

well is there any way to restore this to factory defaults? i mean obviously some new equipment would fix the problem, but i just bought this thing and i'd like to make it work if possible. i'm good at soldering if thats all it would take.

thanks

[JohnClark]

At this point I have no idea what someone may have done to modify this GCX. Give us a call or write to info@voodoolab.com to set up an RMA if you want us to take it in and determine what it might cost to put it back to normal.

[hackersdna1]

Question BMA.. When u set up everything, And u try and turn on one channel it comes on right??? But then when u try another one.. It comes on but the first channel stays on? Is this whats going on?

[espboogie123]

In order to do mesa switching... A simple 1/4 patch or instrument cable must be placed from the GCX OUT/N.O. jacks to the external switching jacks on mesa.

Example:
Loop 1 Out/N.O. > Mesa Ch 1 External switching jack.
Loop 2 Out/N.O > Mesa Ch2 External switching jack.
Loop 3 Out/N.O > Mesa Ch3 External switching jack.
Loop 4 Out/N.O > Mesa Ch4 External switching jack.
Loop 5 Out/N.O > Mesa Solo External switching jack.
Loop 6 Out/N.O > Mesa Reverb External switching jack. if needed
Loop 7 Out/N.O > Mesa fx loop 1 External switching jack. if needed
Loop 8 Out/N.O > Mesa fx loop 2 External switching jack. if needed

Set the Road king foot controller channel selector to FT SW

Set the ground control presets, 1-4 on bottom to your likings. The ground control will be set to normal instead of latching or anything like that.

Set your preset No. 1 to turn on only loop 1 for clean or loop 1 and 6 for clean/reverb.

Set your preset No. 2 to turn on only loop 2 for ch 2 etc....

[blewmeaway]

Question BMA.. When u set up everything, And u try and turn on one channel it comes on right??? But then when u try another one.. It comes on but the first channel stays on? Is this whats going on?

Yes that is basically what is happening, more than one channel engages when i only press one button that is only set for one channel.

I decided to do a little investigating by opening up the GCX and it appears as though it has definitely been modified. Please take a look at these pics and tell me if i clip all these soldered lines, and reconnect the ground, do you think things will be back to normal???!!!!

[JohnClark]

Exactly what I (eventually ) thought... the loops have been internally normaled. If you remove the buss wire connecting the ground pins of all the jacks and the short pieces connecting the tip connections between the loops then this should be back to normal.

The ground connection on the buffer board will connect audio ground of the Guitar In/Out and Feedthru jacks to the chassis ground. This would have no impact on the ability to control your amp. People do sometimes lift this ground point in order to eliminate a ground loop that can occur with some gear through the rack rails.

I hope that helps!



p.s. A note to all the modders out there... LIST THE MODS DONE ON THE OUTSIDE OF THE CHASSIS SOMEWHERE!!!

[blewmeaway]

IT WORKS!!!!!! just had to clip those wires and everything is good to go. THanks so much for all your help