Peavey Mace channel switching problem ?

[Sixties_strat]

I just had to do it, found an old mace sittin in the pawn shop for 150.00 and could not pass it up. Learned my lesson from my previous Classic VTX experience and spent a day cleaning it up. Awesome amp!!! From what I understand from the manual, I should be able to select either channel 1 or 2 via the select switch when the guitar is plugged into the automix jack. (my am has 4 inputs, normal, automix, and effects 1 and 2. the normal input seems to be high gain, normal channel only. The Automix input as I understand it should give me either channel 1 or channel 2 via the select switch or both together if the combine switch is depressed. The effects inputs 1 seems to be high gain channel 2 only and the input 2 seems to be low gain channel 2 only.
Here is the trouble. When in the automix input I cannot seem to select channel 1 alone. I can select channel 2 alone and when i hit the select switch again both channels 1 and 2 become active. The combine switch if activated will combine both channels and in that mode the select switch is not functional. I took the foot switch apart and verified the select switch is functioning normaly, ie, one depress and two legs of the switch are connected, next press and the opposite leg is connected. Took the din apart and looks good there as well, although there was some residual solder on pin 3 and nothing connected there. Tried to verify the din wiring with the peavey schematic for the automix but my wiring does not match up with that schematic. The footswitch functions normally in evey other position, reverb works, phaser works, combine works, just won't let me select channel 1 by itself. Hoping you can give me a shove in the right direction......
Thanks!!
Mike

[Jazz P Bass]

I think you have to go in either parallel or the series input for the channel select to function.
http://www.peavey.com/assets/literat...s/80347000.pdf

[Sixties_strat]

I think you have to go in either parallel or the series input for the channel select to function.
http://www.peavey.com/assets/literat...s/80347000.pdf

I don't have those inputs, mine are Normal, Automix, and Effects 1 and 2.

[g1]

Is this a VT series? If so, http://www.peavey.com/assets/literat...s/80345001.pdf

[Sixties_strat]

Yes VT series, have that pdf. Loks to me like I should be able to select either channel one or channel 2 when plugged into the automix input and I cannot, all I can do is select channel 2 or one and two combined. Thanks!

[g1]

Hopefully not an extinct TL604 problem. Check that the footswitch wiring and amp FS jack solder connections are all good.

[Enzo]

You don't have a Mace, you have a Mace VT.

The automix jack does simply feed both channels, right through their jacks in fact. Understand how it works. The channel selector is a kill switch. IN other words, if you want channel 2, you kill channel 1, and vice versa. You ground a channel kill and it kills that channel. All the combiner does is open the ground connection, so neither kill will work, thus both are one combined. SO apparently you cannot kill channel 2.

Your footswitch might be wired wrong or for a different model. Check first. Note the selector switch has three wires. Two go up the cable to the amp, and the third hops over to the combiner. The combiner has two wires. That jumper, and one that goes up the cable. Make sure the combiner is set to open. Now hook a clip wire to ground, and with the other end touch each of the selector wires that go up the cable. Watch the amp. Does each one kill a channel? And just for grins, ground off that combiner wire that runs up the cable. We want to make sure someone didn;t swap the combiner wire and one of the kills.


If you find that the channel 2 kill won;t work, look at the circuit drawing. The end of each preamp channel ends in a TL604 U18 or U17. The TL604 is not an unreliable IC, but it is probably the least reliable in the amp. If you cannot control the IC by grounding that kill wire, then try swapping it with the one at the Reverb. ANy difference?

The footswitch wiring on the schematic shows numbers down the left row of arrows. Those numbers refer to points in the schematic, NOT connector pins. For example, the combiner wire connects to 1. Look over at the automix jack. The transistor there Q1 connect to point 1 through R79. I have no idea what pin on the DIN connector carries that.

Note the phasor and reverb kill switches are wired to G for ground. That point is also over by Q1. The selector common is wired to point 1, not ground. If you conected it to ground instead, it would always work, whether you were in automix or not. That leaves the possibility you plug into a channel but it is left in kill mode. Q1 only comes on when the base is allowed to pull up by the extra contact on the automix jack opening. That puts FS1 essentially at ground so the selector/combiner works. Plug into one of the channels instead, the auto jack grounds the base of Q1 turning it off, and disabling the kill switches.

[g1]

"Tried to verify the din wiring with the peavey schematic for the automix but my wiring does not match up with that schematic."
How about this: http://music-electronics-forum.com/a...ch-diagram.jpg

[Sixties_strat]

Hey there Enzo
I have been reading alot of your posts, tons of good info in those. I will do as you suggest, got home a little late tonight to try it but will do tomorrow. Thanks for explaining what is actually happening with that switch, had not thought of that possibility. Schematics are kind of confusing to me, I can read em for the most part, just don't have the experience to be absolutely sure I understand what I think I am seeing Really appreciate your help, thanks for taking the time. On a totally different note, do you have much experience with speaker selection for this amp? I was thinking of adding a couple of Jensen Mod Tones 16 ohm in parallel. I know speaker tone is sort of subject to the individuals taste, just thought I'd ask your opinion.
Mike

[Enzo]

I don't make speaker recommendations, there are plenty of people here happy to make their own tastes known though. SUggesting a speaker is like telling you which woman I think is most beautiful. or what is the best dinner on a menu. Your taste in either may well not agree with mine.

I will say that in one case I like the crabs, in the other case, I do not.

[Sixties_strat]

Well Fellas........
Thanks to Enzo's excellent instructions I now have a working footswitch. Turns out the jumper from the "combine" switch was on the wrong terminal of the "select " switch. Changed them around after verifying correct function and all is perfect now. Can't thank you guys enough for your help!!!
Mike

[Enzo]

Score another one for "it ain't the parts, it's the circuit".

[Jazz P Bass]

Well Fellas........
Thanks to Enzo's excellent instructions I now have a working footswitch. Turns out the jumper from the "combine" switch was on the wrong terminal of the "select " switch. Changed them around after verifying correct function and all is perfect now. Can't thank you guys enough for your help!!!
Mike

There is a schematic floating around that shows just that.The 'combine' & 'select' switches are drawn incorrectly.
Glad that you got it.

[Enzo]

That is why I am always hesitant when guys ask "what color wire is the channel switching" or some such. I always verify the functions by continuity rather than some drawing. Many time I have poked a grounded paper clip into a FS jack to test which pins did what.