Help building Hughes & Kettner ATS 120 Stageboard

[dinkyguitar]

Hi All,

I want to make a stageboard for my ATS 120 combo amp. Here's the actual stageboard.



My schematic without LED's is here:



Clean, crunch and lead are momentary switches, and reverb & FX are on/off switches...push on, push off.

I've built this pedal but without led's and would like to incorporate them into the circuit but don't know how.

I found a schematic of a Hughes & Kettner TRIAMP footswitch and it has diodes in the schematic...no resistors, or cap. Just switched, LED's, and diodes.

It's a 9 PIN cable and one of the PINS carries a 22v lead.

Can someone help with designing this board?

[duck_arse]

hello and welcome, dinky. I recently replugged a pair of tri-amp stageboards. the head has a shirtload of "stuff" to logic out and drive the leds, with help from the diodes you noted.

do you have a circuit for the ats120? does it have a 22V line to the 9pin connector?

[dinkyguitar]

I don't have a schematic for my amp....

But one of the pins has 22v....

Here's a schematic I found for a stageboard on the Hughes & Kettner Triamp. Granted it's got more LED's, but I was thinking if I can use this schematic to build mine.

The only thing that confuses me is the diodes...not sure how they tie into the circuit.



It's not the most clear image, but the bottom rows are your switched. 6 momentary's & on/off for the FX.

The middle row are the diodes, then above that are the LED's.

dinky,

dinky,

[duck_arse]

those tri-amp diodes do, erm, something, along with the logic in the head. had me baffled then, as now.

if your 120 uses momentary switches in the stageboard, there must be some latching logic in the head. it could, might be the same as the triamp, but we'd need a circuit diagram. I searched up the whole tri-amp manual, circuits and board layouts.

[duck_arse]

found: go to page six, circuit is all there!
http://music-electronics-forum.com/attachments/24315d1374432916-ats120-service-docs.pdf

Fuss schalter?

[dinkyguitar]

How the hell did you find that?

I've been looking so long.....thanks a bunch!

so we're on the same page, the circuit I'm looking for is this on page 6.



I guess those diodes somehow keep the LED's on till you press another switch....

Do you see any indication which are momentary switches and which are on/off switches? I think I know....but just checking.

And being one lead has a 22v supply, what type of LED rating should I get?

BTW what is Fuss schalter?

dinky,

[bluebunny]

BTW what is Fuss schalter?

"Foot switch" in German.

[dinkyguitar]

BTW what is Fuss schalter?

"Foot switch" in German.

ahhhh....

dinky,

[PRR]

> diodes somehow keep the LED's on till you press another switch....

No. The top of that page shows T14 T15 T16, a rare 3-state flip-flop-flip. Which ever transistor is shorted-out by a switch then turns-on and also turns-off the other two transistors, forever or until another button press.

The 1N4007 in the footrest do not look essential... but they may cover some odd back-bias condition, and they cost just pennies, so do them.

These are, of course, the momentary switches.

The LED current is around 9mA, *all* LEDs can stand 9mA and give good light, use any LEDs.

FX and Rev are handled very different, appear to require latching switches.

[duck_arse]

from the triamp, which uses the same rare circuit PRR said, the clean, crunch, o/d switches are momentary. the fx was latching, didn't have a rev, but it's shown the same setup as the fx fuss schalter, so latching there too.

like prr says, the h&k engineers don't just decide "let's put ze diodens here here und here", not even in pig german, so you might as well. do you have any specific build ideas?

PRR - the clean channel transistor has a 33nF base cap while the other two have 100nF. would that difference be enuff to "initial state" the f-f-f?

[PRR]

> enuff to "initial state" the f-f-f?

Good eye. Maybe it does init the latch to a starting state.

Such things are often unreliable if the power start-up rise changes (power caps decay with age, or someone up-sizes a filter cap). However this isn't really a crush (or crunch) machine, nobody dies if it happens to power-up in "stun" instead of "safe".

[dinkyguitar]

So I bought materials to make this footswitch and I wired it all up.

I go to press the crunch channel, which is supposed to be a momentary switch and it latches.

When I got all the switches I labeled 3 momentary, and 2 latching.

Now I got 1 that should be momentary latching.

Not only that, but I took a momentary one apart, put it back together, and it turned into a latching.

Are these "really" momentary switch turned into latching when I press them?

Can't figure it out, since I tried all my switches and I know there were 3 momentary switches....now I need 2 momentary switches.

Piece of crap switches!!!

dinky,

[duck_arse]

can we see the switches? any chance you took pics while disassembled?

[bluebunny]

I go to press the crunch channel, which is supposed to be a momentary switch and it latches.

Is it really electrically latching?  Or is it simply clicking?  I made the opposite mistake - picked up a switch which clicked (an Alpha), and assumed it was a latching switch (like the majority in my box o' parts).  It was momentary.    Took a while for my brain to work out what was going on...

[dinkyguitar]

They were mechanically switching...I'm returning them so I don't want to take them apart anymore, but I bought better momentary switches with only 2 connectors instead of 6.

The seller says I can return them provided they were not soldered. The broken one even though soldered I can return, but the other 2 I already soldered.

I sent an email saying, I ordered 3 momentary switches, but I was shipped 2 latching and 1 momentary but found out they was latching after soldering them in.

So is it my fault they didn't ship me what I ordered?

I'll probably get screwed......

bluebunny,

I checked the switches with a multimeter since they all looked the same. I wasn't sure which was what.

Guess I'll have to wait till I get my other switches.

dinky,

[bluebunny]

. . . since they all looked the same.

May not be immediately helpful to you, but the Alphas are stamped with L or M:

[dinkyguitar]

That would have been helpful!

Especially to the seller...since I ordered latched and momentary, he might have sent me the wrong ones....still not sure how I messed up when I was checking them with the multimeter.

Anyway, I'm returning them, and hopefully I'll get a refund.

I've since ordered new ones and temporarily I'm using my good ole trusty 20 year old Radio Shack ones.

These are the same switches I used when I originally made my crude footswitch for this amp.....

dinky,

[dinkyguitar]

So I finished the pedal 

Special thanks to everyone and duck_arse!

Here she is:



And in action:

http://youtu.be/fQiNMC1EyrI

Works perfectly!

dinky,

[duck_arse]

geeze, it looks like a bought one. nice work.