Maestro Ring Mod Build Report, question.

[Ry]

Woah, I didn't see your last couple questions.  Sorry about that.

I'll try my best to answer your questions here (let me know if I'm not understanding what you are asking):

You do need all four voltages, it works according to the circuit schematic for the pedal.  The 1458 and 741 op amps use 15v and the 1495 uses 12v.  The power supply schematic at GGG was wrong, look at the one at:
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=23268

for an idea of how to make all four voltages.

As for the jacks:  J1 is input, and the output is the one on the top right hand side of the schematic, you are right about that.  The other ones are not absolutely necessary to the function of the circuit, but they are neat to have.  J2 is the modulation input, it is a stereo switching jack that will allow you to input a different modulation source.  J4 is a pitch pedal input, which is also stereo switching.  It allows for an expression pedal input (I think, I haven't wired these up yet). J3 is a mono jack.  It is an input for a carrier signal (from another instrument, for example).  J5 is a mono jack that provides an output of the 741 oscillator.

They don't have anything to do with the trimming other than what the instructions say to do with them.  I just jumpered them according to the instructions.

Ry

[Brunetto Latini]

Another problem is with the Parts Layout diagram. It doesn't seem to tell us where to hook the power up to. It doesn't look like the power is connected to all the components that require it, on the parts layout diagram that is.

The instructions also mentioned empty pads that were marked "A" and "B" but I haven't seen anything marked yet.


I have no info on these switches, sw1a and sw1b. I'm assuming there a part of the mods done to this for true-bypass; but what kind of switches do we have to buy? Where to put them in? They are only mentioned in the schematic but nowhere to be found on teh parts layout.

[Zero the hero]

The Part Layout picture doesn't show any external connection cause I draw another gif file with these important info. I don't know why there is no link to this picture in the GGG site.
I'm going to send it to you via mail, and I'm going to ask JD.
I've drawn another power supply shematic, i hope to draw the PCB as soon as possible.

[Brunetto Latini]

The Part Layout picture doesn't show any external connection cause I draw another gif file with these important info. I don't know why there is no link to this picture in the GGG site.
I'm going to send it to you via mail, and I'm going to ask JD.
I've drawn another power supply shematic, i hope to draw the PCB as soon as possible.

Is this new power supply schematic significantly different from the new one that's been linked in this thread?

I found a 18V transformer, non VCT, lying around and just decided to give the dual power supply shit a shot. Of course, if the schematic you're working on is a lot easier, I can wait.

I hope you mean e-mail heh

[Zero the hero]

No, it's not that different. It's the same as the one I posted days ago, but it gives both +-15 and +-12.
Ry, as far as I know ALL the trimpots influences the sound of the unit. People, I'm overwhelmed by things to do, I hope to finish all the jobs I'm carrying on so I'll be able to correct everything in this circuit.
I've read 1458 and 741 datasheets, and +-12v are suggested supply values. 741 will work even with +-22v.
I don't exclude that the Maestro will work with +-12v.

[Paul Perry (Frostwave)]

I'm obviously having problems finding a 15V transformer,

Most domestic burglar alarms use 15 or 16v AC transformers, so that is one source.
The power supply circuit that Ry referred to, is exactlyu how I do it in my commercial (Frostwave) Blue Ringer, except I use +- 15v rails.

[Paul Perry (Frostwave)]

http://www.rk-elettronica.it/
looks like a source of transformers (and other stuff) in Italy, they appear to have a tranny with dual 15v windings, might be a bit large though.

[Ry]

The thing about the connections of the pots, jacks, switch, etc is that you can take the schematic and the layout, put them side by side and figure out where the connections go.  Just look at what components are near the part you're looking at...having two resistors or a resistor and capacitor connected to the same point as the lug of your pot is a dead giveaway.  This is how I figured mine out.

Ry

[Zero the hero]

I have uploaded in my photo bucket account the missing pics for the maestro ring mod.

http://photobucket.com/albums/v368/zero_thehero/

under the "electronics" album you'll find the power supply schematic, PCB and parts placements diagram. I uploaded a pic showing the connections too: That's a missing pic from the GGG site.

[Zero the hero]

I forgot to say that thePCB for the new power supply is still UNTESTED. I'm going to build it as soon as I can.

[hitech]

Hello all ....
Ive just finished  the maestro ring mod from the GGG site .
The power supply i used was a 7660s  booster n voltage inverter  , which gave  enough current to run the ring mod.
Its definetly the most compact  ive come across .
Posting a link below .

http://tagboardeffects.blogspot.in/2014/01/providence-stampede-od-sov-2.html?m=1

Just used 7815, 7915 and 7812 ,7912 regulaters aft the 17v out with 420 uf caps . ( any  reservoir  cap values)

Thought it might help future builders
Cheers

[Paul Marossy]

Does anyone know where "test point A" and "test point B" is on the GGG schematic? The service manual (the part that I can find) talks about these test points but I don't see them indicated anywhere on the GGG schematic or PCB/parts layout.

http://www.generalguitargadgets.com/wp-content/uploads/maestro_ring_mod_sc.gif
http://files.effectsdatabase.com/docs/schematics/maestro_ringmod_trim.gif

[Govmnt_Lacky]

Does anyone know where "test point A" and "test point B" is on the GGG schematic? The service manual (the part that I can find) talks about these test points but I don't see them indicated anywhere on the GGG schematic or PCB/parts layout.

http://www.generalguitargadgets.com/wp-content/uploads/maestro_ring_mod_sc.gif
http://files.effectsdatabase.com/docs/schematics/maestro_ringmod_trim.gif

I can see Test Point A on the schematic (just to the left of Pin 9 of the 1495 chip)

No sign of Test Point B. Maybe it was 'written over' when the component ID numbers were added??

EDIT: Test Point A appears to be Pin 9 of the 1495 IC. Test Point B is Pin 7 of one of the 1458s

http://files.effectsdatabase.com/docs/schematics/maestro_ringmod.gif

[Paul Marossy]

Does anyone know where "test point A" and "test point B" is on the GGG schematic? The service manual (the part that I can find) talks about these test points but I don't see them indicated anywhere on the GGG schematic or PCB/parts layout.

http://www.generalguitargadgets.com/wp-content/uploads/maestro_ring_mod_sc.gif
http://files.effectsdatabase.com/docs/schematics/maestro_ringmod_trim.gif

I can see Test Point A on the schematic (just to the left of Pin 9 of the 1495 chip)

No sign of Test Point B. Maybe it was 'written over' when the component ID numbers were added??

EDIT: Test Point A appears to be Pin 9 of the 1495 IC. Test Point B is Pin 7 of one of the 1458s

http://files.effectsdatabase.com/docs/schematics/maestro_ringmod.gif

I see it now. Test Point A would be Pin 4 or Pin 9 of 1495? I just found Test Point B on the schematic, I believe. It's at junction of Pin 7 of IC-2B, R18 & R19. No circle around it.

[Govmnt_Lacky]

I see it now. Test Point A would be Pin 4 or Pin 9 of 1495? I just found Test Point B on the schematic, I believe. It's at junction of Pin 7 of IC-2B, R18 & R19. No circle around it.

Check the schematic link I sent in my previous post. Shows where both points are located.

[Paul Marossy]

I see it now. Test Point A would be Pin 4 or Pin 9 of 1495? I just found Test Point B on the schematic, I believe. It's at junction of Pin 7 of IC-2B, R18 & R19. No circle around it.

Check the schematic link I sent in my previous post. Shows where both points are located.

Got it. Thanks!