Triaxis internal switches

[guitardude]

Hi all.... Great board...

Does anyone know what the function of the four internal switches inside the Triaxis are for? They are located on the main tube PCB toward the back of the unit.

Thanks,
Bob

 

[fatboy135]

The programable switches??? that are near the outputs???
They are to control external hardware like if you were using external stompboxes to switch. You can programate them. They are for control relays from other machines on your setup.

 

[guitardude]

I'm not referring to the external switches 1-4. These are inside the unit mounted directly on the PCB which contains the circuitry for the analog signal path. They are not DIP switches that you would typically find inside a computer, but they are rather small.

Bob

 

[fatboy135]

ahhhhhhhhhhhhhhhh of course man, welcome to the triaxis jungle...
This switches are used to calibrate the ldrs optos of the triaxis.
The optos has a internal resistance that depends of the manufacturer for this reason an accurate calibrate is needed to get the exact values of the interface frontal parameter, for example you see that there is the lead2drive parameter, ok if you go to the mux/demux that route the signal you can see that the highest value is for a 1Mohm resistor then if I remember well, it becomes a non inverted operational amp with a pot ( a variable resistor ) in the feedback loop to adjust the gain.
Well you get the triaxis on calibrate mode, just shortcircuiting the terminals that are named factory load on the digital board Tx2. Then you take your multimeter on put one of the poles on the ldr23 outleg and the other pole to ground.
The factory defaults put the triaxis in a calibrate mode, where all the parameters are setting to 10. Ok then you must to close the switch labeled sw4 and work over the tp4 potenciometer on the analogo board.
This switches isolate the optos from the rest of the circuit to allow a perfect calibrate. You must see exactly 1 Mohm on your multimeter, if you didn´t have the 1 Mohm turn the potenciometer until you get it...
Easy isn´t it????
Of course I´m telling you this with my poor memory, you must to refer to the official service manual for repairs about the triaxis. It is just 44 page and it becomes with all the measures and some pictures with oscilloscope signals over the presets

 

[guitardude]

Wow !!! amazing amount of info. thanks

Where can I get a copy of the service manual?

Thanks,
Bob

 

[fatboy135]

Service repair manuals is not able for ordinary customers, think that there is confidential info, with some patents and some circuits waiting to be patent.
Mesa/boogie only gives you that info if you they meet you or if you have a good reason to need that kind of info.
Due that I not have an special agreement to copy here all the info that you need, I will copy only the most special things that you must to know for calibrate it.

From mesa boogie service repair manual:
" Factory Load: In order to perform the calibration correctly, the Factory Load must be performed. The
Factory Load resets the unit and loads the factory presets into the memory. However-- if the user presets
have been changed and saved, the Factory load will overwrite those presets and they will be lost. If you
need to save the presets that are programmed into the unit, then you will need to transfer or “dump” them
to an external storage medium. This procedure is outlined in the Triaxis owners manual on pages 4 and
5. (Note: The stored information can be transferred to another Triaxis for saving if necessary). To
perform the Factory Load: Turn the unit on and set it to any Program except Program 1. Find the
Factory Load pads on the TX2 board, at the front edge directly behind the Dynamic Voice control.
Simply short the two pads together with a screwdriver or a pair of pliers. The unit should revert to
Program 1. This will indicate that the factory Load has been completed. After the Factory Load, check
the controls to see if they respond correctly. If a calibration is not needed, skip ahead to the bench test."
...
"Due to variables in the manufacture of the LDRs, they must be calibrated in order to operate in a
predictable manner. This is done by measuring the resistance on the cell side at a specific setting while
changing the voltage (and therefore the current) on the LED side. The voltage is set with a trim pot."
...
"1) Turn the unit on, and set it to Program 1. Push the Shift key once. The Program/Channel display
should flash three times. Now perform the Factory Load. This puts the unit into the calibration mode. All
the parameters should now read 10, except the Presence which reads 5.0 and the Dynamic Voice which
reads 1.0. The mode should be Rhythm Green and the Loop LED should be on. The Preset and Program
should read 01. Set the VOM to ohms.
2) Middle: Connect one side of the meter to ground, and the other to the outside leg of LDR 21. Using
TP6, adjust until the resistance reads 33K.
3) Bass: Leave the meter connected to the outside leg of LDR 21, and connect the other lead to the
outside leg of LDR 29. Using TP5, adjust until the resistance reads 1M.
4) Treble Low: Connect one lead of the VOM to the outside leg of LDR 27, and the other lead to the
outside leg of LDR 28. Using TP7, adjust until the resistance reads 215K.
5) Treble High: Move the lead that is connected to LDR 28, and connect it to the leg that is next to the
outside leg of LDR 27. This means that the meter will be connected to the two rearmost legs of LDR 27.
Push the Treble down arrow on the front panel once-- the Treble should now read 0. Using TP8, adjust
until the resistance reads 240K. Push the Treble up arrow on the front panel once-- the Treble should
read 10 again.
6) Gain Low: Connect one lead of the VOM to ground, and the other lead to the outside leg of LDR 18.
(This is the top LDR of the two). Pull V2 from it's socket. Using TP10, adjust until the resistance reads
1M.
7) Gain High: Move the lead that is connected to ground and connect it to the forward leg of C801. This
cap is located on the left edge of the TX1 board. Push the Gain down arrow on the front panel once-- the
gain should now read 0. Using TP9, adjust until the resistance reads 1M. Reinstall V2, and push the Gain
up arrow once-- the Gain should read 10 again.
For the remainder of the calibration procedure, one lead of the VOM will be connected to ground.
8) Lead 1 Drive: Connect the VOM lead to the outside leg of LDR 20. Using TP11, adjust until the
resistance reads 680K.
9 ) L ead 2 Drive: Connect the VOM lead to the outside leg of LDR 23 (the top LDR of the two). Using
TP4, adjust until the resistance until it reads 1M.
10) Presence: Connect the VOM lead to the left side of C002. This cap is located in the middle of the
TX1 board, just to the right of LDR22/23. Using TP3, adjust until the resistance reads 180K.
11) Dynamic Voice: Connect the VOM lead to the outside leg of LDR 24 (the bottom of the two). Using
TP1, adjust until the resistance reads 15K
12) Master: Connect the VOM lead to the outside leg of LDR 25, directly above LDR 24. Using TP2,
adjust until the resistance reads 100K."
...
That is for the non phatt mod. The phatt mod is the same manner but you must to calibrate all the ldrs for the recto mod ( there is another page with that info ). I think that with this info you have enough info to calibrate it. Good luck.

 

[guitardude]

Great !!!! Thanks for all the helpful info.

Didn't think it would be easy to get a copy of the service manual

I have a couple more questions if you don't mind.

The owner I just purchased this unit from claims it has the version 2 firmware and no phatt mod. The serial number is T0225 and tech support at Mesa says there is no record of that unit being updated at their plant. The powerup sequence of the LEDs doesn't indicate the version number as it's supposed to. Upon power up all LEDs are off expect the rightmost one (dynamic control) display. It displays a different number each time I power it up (0.0 4.0 6.0) :?

But, the unit seems to work fine. It sounds good and I can save and recall presets. Haven't tried and MIDI stuff yet.

Any thoughts ??????

Thanks,
Bob

 

[fatboy135]

ohhh t0... It must be from the 1992. It is the triaxis O.S 1 to upgrade it to the version 2 you must only to replace the eprom on the tx2 and inside the metal box. To replace the eprom you don´t need to send the machine to petaluma, you only need the eprom, a couple of minutes and a bit knowledge about replacing IC into the sockets.
When a 2.o is installed you will see a 2.0 over all frontal interface parameters.
There is a couple of bugs issued and repaired on the version 2.0 and there is a continuous controller software to change the parameters. Nothing else. If you want to use an expression pedal get the new eprom.
If you don´t think the continous parameter is not necessary to upgrade it.

 

[snowman3000]

THANKS A LOT MAN! Very helpful infos....too bad that my triaxis is on the other side of this crazy planet =)

Any infos about the lead2yellow? (i mean...what would you do to make it sound more like the real C+?)

 

[fatboy135]

I run a personal poll over all the greatest musicians on my country that have a triaxis on their set ups, the last conclusion is the triaxis sounds so great and no mod is needed, I speak even with Jose de Castro ( one of the best musicians players www.josedecastro.net ) and he told to me that he have two triaxis in cascade, one with some mods and other in a classic status, and at last he only uses the classic. Believe me, the triaxis doesn´t need any mod. The only mod I do on my triaxis is a tech mod, only to get a better S/N ratio. Not looking for a special tone. Even the mod that I do doesnt affects to the tone design of the triaxis. It is just on the end of the tone chain, just an output mod that can be controlled with the two outputs pots.
I could give you a lot of mods, but think that everybody that mod it, doesn´t like the final results. I think that mesa waste much time on R&D with the triaxis and I think that the triaxis has the summit tone of mesa.
Conclusion: No mods are needed

 

[snowman3000]

Conclusion: No mods are needed

Probably you're right...almost....Triaxis does sound great....i'd try to experiment a bit with the dynamic voice to see if it possible to tight up a bit lead 2 yellow (which is very good indeed but a bit loose on the low-end) and mod the lead 1 red, it doesn't sound like a recto at all. To me!

Do you have any suggestions?

 

[fatboy135]

the lead 1 red is the best circuit to mod, because it has its personal circuit.
If you try to mod the lead 2 yellow you will be modding the completely lead 2 channel. But if you want to mod the lead 1 red you will be only modding it because it works on a stand alone mode.
Ok here we go...
Since the signal pass the tube 3A there is a splitted way from ldr6 and ldr 7 over the tx4, if you are not running the recto mode the ldr 6 opens and the ldr7 close to let the signal pass to the presence circuit and the to the master. Well if you are running the recto mode, ldr6 and ldr 1 closes and ldr7 opens, passing all the signal into the recto circuit.
On the recto circuit we can see that the tube 3b is the master of puppets in our sound, we could see a feedback resistor on the plate pin to the grid to get a negative feedback to settled the circuit in a good condition. After the tube 3b we can see the eq for the recto mode, the trebble with two optos, ldr 2,3 the bass with the ldr 4 and the mid with ldr 5, if you really want to take advantage over the recto mode you will need to mod the relation between the values that are multiplexed for the the ldr 2,3,4, 5 and the value of the caps C2, C3, C4, I recomend to you to test it first on a cad program like orcad to avoid oscillate circuits, with the new values.
After the eq section we can see the volume adjust with a resistors net. If you want more gain or volume you must to increase R4 and decrease R3 and R5.
Working on these mods are so easy because all the components are on the tx4 board, all you need is to extract the little pcb and work in it.

 

[frednerk_30]

Anyone know of a good tech who would be capable of repairing/servicing a Triaxis in Australia. Someone who actually knows their stuff.

 

[LUCRETIA]

I thought theres a Mesa service center in Australia?

 

[frednerk_30]

...

 

[fatboy135]

what happens with your triaxis????

 

[frednerk_30]

All LD11 modes (G,Y,R) change over 10 minutes and become thin and a lot less over-driven. They become so trebly (and less mids) that setting the treble and presence controls on 0 (zero) still wont correct the tonal balance. They also lose most of the gain and sound much cleaner. If I select another preset (say R1) and then switch back again to the LD11 preset it seems to recover the proper gain and tonal balance but then it starts all over again as described above but much quicker.

 

[fatboy135]

This some trouble were posted but I don´t remember the place, I´m sure that I had seen this trouble and the solution on the forum or maybe on neighbourhood forums.
The lead 1 red is completely stand alone in phat mod triaxis. They have a special stage tube for the recto purpose ( the V3B ). The lead 1 green and yellow becomes from the first stage of the first tube (V1A).
The triaxis is a great complex machine and I need to have the machine at my home with my oscilloscope and tools to do a correct diagnostic, but the sympthoms that you describe makes me to think that it is posible to have a wrong z80cpu or something corrupt on the digital enviroment.
Think that if it is something wrong with the analog circuit it will fail all the times, even if you do the steps and ritual to recover your sound. The trouble of get the trebble and presence to zero and it is still so trebbled could be by wrongs optos, wrong IC´s, wrong conexion, or a bad digital.
The digital enviroment manage all the functions, is leads all the optos that must to be open or closed, the correct values on the analog multiplexer for treble, presence, etc....
Then I think that after some minutes the machine becomes to loose the lead1 there are all the bets 5:1 that the digital enviroment is wrong. Because if it was the analog, the analog will fail ever, independly the secuence you do to recover the sound ( changing the red, etc... )
Some components on the digital have strange issues at high temperatures.
If you say me that it only fails on the green and yellow I think that the trouble will be on the first tube, but in phat mod triaxis the red is totally independent of all the circuit.
The first thing to do is given us your triaxis serial number to see the version.
If you have a version 1 all I coment before is only trash

 

[LUCRETIA]

All LD11 modes (G,Y,R) change over 10 minutes and become thin and a lot less over-driven. They become so trebly (and less mids) that setting the treble and presence controls on 0 (zero) still wont correct the tonal balance. They also lose most of the gain and sound much cleaner. If I select another preset (say R1) and then switch back again to the LD11 preset it seems to recover the proper gain and tonal balance but then it starts all over again as described above but much quicker.

Sounds to me like a tube problem.It happened to me also.But mine is worse.Both the LD Drive keys are active in all modes...

 

[fatboy135]

Sounds to me like a tube problem.It happened to me also

If it is a triaxis 1 maybe the tube is bad, but in triaxis phat mod ver.2 the recto mode is an stand alone with a special board for it, if the lead 1 fails completely I think that it is maybe a digital decoder corrupt, because lead1 uses the famous presaturated circuit that satured the signal before the tone control, that is the reason that lead 1 modes are on the V1 and the gain and tone controls are on the V2. The recto mode is totallu diferent. It uses a post gain topology that becomes on the V3. The V3B is for the recto sound The V3A split the signals in two pathes two optos that are closing or opening in fact of the mode you are using.
If you are on recto mode on opto closes and opens the V3B to signal inputs into the V3B, if you are not using the recto mode, the opto opens a bypassed path to skip the V3B from the recto sound.
For this reason it is imposible to be only just one tube, if there is failing all the ld1 modes there must to be at least 2 tubes wrong, and if the recto mode with the V3B is wrong, all the sounds will be wrong, because the V3A is a common tube for all the modes.
I don´t know if I explain well, all I can to say that if you have a phat mod triaxis the recto and ld1 modes are totally independent, and if they are failing all together, there is maybe a digital trouble.

Both the LD Drive keys are active in all modes...

Explain me your problem and I will try to help you