Triaxis LD1 Red and LD2 Green Problem

[ammo]

Hi...
I need some help...

I have a Triaxis, 2.0, with this problem:
The LD1 Red and LD2 Green modes, sound equal. If i build, for exemple, two presets with the same values, one on LD1 Red and another on LD2 Green, when i change from one to another, nothing happens to the sound, the sound doesn't change, is equal... the preset change, the mode change, but not the sound...
Also the LD1 Drive Key and the LD2 Drive Key are active in both modes simultaneously : If i'm in LD1 Red mode, and increase LD2 Drive, the output drive of LD1 Red mode increase (not the value), and if i'm in the mode LD2 Green and increase the LD1 Drive, the output drive of the LD2 Green also increase.
Before this problem, the LD1 Red drive was powerfull, but not any more, it's like a bad pocket amp with bad blues overdrive...
It looks like these two modes are just one (no difference between them), with both drive key active (i can increase one up to 10 plus the other up to 10 too and sum the two drives), and a very bad drive sound...

At the beggining, with the "inboard" factory reset, the problem disappears, but not any more...
I hope someone could help me on this problem...

I'm sorry for my english...
Ammo.

 

[crane]

Looks like an optocoupler problem (like relays, change signal path when changing mode). Give unit to a Mesa tech, or if you're good at soldering you can change optocouplers yourself, but findint wich one is bad could be tricky, and if you want to change them all it will cost some money....

 

[ammo]

Hi, Crane.
Thanks for your help... Last week, I've tested the TX4 Board opts, they seemed to be ok, now i need to try the rest, but it's a hard job...
I found schematics on the web to follow, there are two opts that aren't working when they should be, precisely when i select LD1 RED and LD2 GREEN, but they work with other modes, thats why i say they seem to be ok... I'm wondering if it could be the IC's, but i do not have sufficient info to test them...
I also changed the ribon cables...
The parts (soldering, etc) is not a problem for me, isolate the problem is the hard part...
Here, the filosofy of the assistence, is: "Send us the triaxis, pay us to open and see what to do, then pay a lot for the repair...". I've already sent 2 emails for them asking for "help", without any response... Some times, it's not an expensive repair, and we can do at home... I would prefere to try...

 

[Jackie]

If you solve this on your own, do report please.
I have a funny problem myself that's sort of related. My Lead 1 Red Channel gets "stuck" whenever I footswitch there, and then it flips to whatever channel I select at a completely random switch command (sometimes immediately, sometimes after 10 stomps). No means to jack this thread, I'm merely mentioning my issue.

 

[ammo]

...does anybody have some usefull information to share with me regarding this problem, or similar problems, and how should i test the IC's? I've read also, that the digital part controls the IC's... Does anyone know how can we test or reset this digital environment?

 

[msi]

There is only one IC used in the switching circuit, its a 75492. There are two additional jfets used which are a pair of 2N6426 for Rhy 1 and Rhy 2. The schematics refer to the IC as IC16 on PCB TX3a. Look at the schematics, it'll tell you which port needs to be open to ground for which mode.

Personally, I'd man up and send it to mesa to get it up to snuff, then if it has problems at a later date tackle those myself. Your dealing with a 20 year old piece of gear with temperamental components (LDRS) and looking to do the repair on the cheap. That's a bad place to be in.