Mesa boogie switching matrix

[fossilshark]

Im having a bit of a problem understanding the switching matrix. I know the LDRs in the preamp are actually point in the matrix but im having trouble understanding where the matrix connects to the preamp. I dont know if i explained this well so please ask questions if needed http://www.freeinfosociety.com/electronics/schemview.php?id=507

[shooter]

where the matrix connects to the preamp

All those "switch" contacts in the pre are the "connecting" points, the truth table lets you know what those "switches" do under each condition.  study the notes where it says RY1 lifts ldr 3,4,10, (turns off) adds ldr 16,20 (turns on)

Looks like they hired some outta work logic guy to really mess with a guitar players head, YA!

[fossilshark]

So in the switching matrix, where does it say to connect the contact point? For example LDR1 (input select) is labeled where on the schematic? Does it have to do with these numbered contacts? And the optoisolators outlined and numbered are just what controls those switches?

[shooter]

on a real schematic all those relays, (ldr's?) in the string you referenced would have designations like K1, K2...,
The contacts would be labeled, so without that, the truth table says if you want OR NORM, ldr 1 is off, 2 off, 3a n b on.........but which one is one, two, 3, that might take crayons to trace out!

[sluckey]

The pic you posted is a relay, not an LDR.

The LDRs used in this amp are optocouplers that consist of two totally separate parts that are housed in a single plastic case, an LED and a phototransistor. For simplicity the two parts are shown separately. The LED is the controlling light source and is shown on the matrix schematic. The phototransistor is the switching element and is shown as a switch on the preamp schematic. When the LED glows, the switch is on. When the LED is dark, the switch is off. There is no electrical connection between the control LED and the phototransistor switch. Since there is no electrical connection between the two parts it is often best to show the control circuit (matrix) separately from the actual switch element.

A complete LRD is shown on the matrix schematic. And the LED for LDR1 switch (phototransistor) is also shown on the matrix schematic and is simply labeled "1". It's corresponding phototransistor switch element is shown on the preamp schematic and is labeled LDR1.

[fossilshark]

Could i theoretically just use the truth table and draw up my own matrix schematic? I think i understand now so mabey ill just draw up my own with relays. Thanks

[fossilshark]

Also, what is "V1 output pad" on the preamp schematic

[sluckey]

Also, what is "V1 output pad" on the preamp schematic

Do you mean "V1A output pad"? That's just a name given to describe the function of LDR 4. Just like "RD input sel" describes the function of LDR 1. Look in the truth table.

These names make sense to Mesa but may not always be obvious to the casual observer.