amplifiednation wrote:it was like open heart surgery to put that 22M back on the relay.
Steve, why would I switch the bass and treble wires?
Take a look at 124 wiring of the r/j switch and PAB relay and compare it to the hybrid wiring.
On the 124 wiring, the left side common terminal of the rock jazz switch goes thru the common terminal of the relay, then to the treble pot.
On the hybrid, the left side common on the r/j goes thru the common on the relay, then to the bass pot.
It appears that the hybrid layout has these connections reversed from the known-good 124 layout. I am not certain that this matters at all (I haven't drawn it out schematically yet to see the differences visually...i can't wrap my brain around it totally by looking at just the layout). However, it is a difference and could be something to do with the problem.
Worst case, it is an easy thing to try.
Steve
From my understanding of the relay, those two terminals have continuity as the relay is "normally closed" to the commons when the relay isn't powered. This is what keeps the tone stack connected. If the wires are switched, it's not going to change anything as they'll just be connected in reverse positions (electronically the same).
The point of the PAB relay is when it's powered it switches the connection to the 'normally open' pair of contacts, which in the case of the PAB, is nothing...disconnecting the treble and bass pot and providing a gain boost as there is no longer tone stack loss.
It appears Dumble has the two reversed probably for easier wiring of the 22M resistor to the Bass lead from the common terminal, because if his wires were reversed, they would still be normally closed when PAB was closed.
Darin's build had problems with the PAB not working correctly and he ended up having issues with his footswitch wiring that caused the problem.
But in that thread it was discussed that the way 102 and 124 are wired (and i think the hybrid layout) that the wiring is used with an on/on/on switch, where the middle position engages PAB.
I looked at 183, which has different wiring using an on/on switch.
Maybe that is the issue?
question 1-
So with the relay, if the commons are allowed to connect (which is what would happen in the middle position) does that essentially 'open' the relay??
question 2-
Is there a difference between a SPDT on/off and on/on?
question 3 -
with the rock/jazz switch that i have, which might be on/off...what happens in the 'on' (rock) position? Does it connect the middle terminals, which are the commons on the relay, thus opening the relay?? and then closes them in the 'off' (jazz)
I have a three position switch here, I'm going to do some continuity testing to answer my questions unless someone beats me to it. I gotta go do some work that pays me for a little while.
amplifiednation wrote:Darin's build had problems with the PAB not working correctly and he ended up having issues with his footswitch wiring that caused the problem.
But in that thread it was discussed that the way 102 and 124 are wired (and i think the hybrid layout) that the wiring is used with an on/on/on switch, where the middle position engages PAB.
I looked at 183, which has different wiring using an on/on switch.
Maybe that is the issue?
question 1-
So with the relay, if the commons are allowed to connect (which is what would happen in the middle position) does that essentially 'open' the relay??
question 2-
Is there a difference between a SPDT on/off and on/on?
question 3 -
with the rock/jazz switch that i have, which might be on/off...what happens in the 'on' (rock) position? Does it connect the middle terminals, which are the commons on the relay, thus opening the relay?? and then closes them in the 'off' (jazz)
I have a three position switch here, I'm going to do some continuity testing to answer my questions unless someone beats me to it. I gotta go do some work that pays me for a little while.
Taylor,
I sketched out the 2 circuits and attached a PDF copy.
The difference where pins 2 and 9 of the PAB relay connect. I am not sure if the different wiring will make a difference, but it is definitely connected slightly differently.
With an on/on switch, the center common terminal is either connected to the top contact or the bottom contact.
With a 3 position switch, when it is in the middle position, the center common terminal is not connected to either of the other two contatacts. This electrically performs the same action as opening the PAB relay.
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you are spot on about the relays...my idea was incorrect. i was thinking the NC terminals were internally connected, when they aren't, there connected through the common terminals.
i better go change my post before someone 'learns' anything from it.
my iron is warming up. it will be cool if thats what the problem is.
also-- i just did a continuity test on the switch when it's the rock position it connects the middle terminals, and just realized I shouldn't be shocked - because the bottom two terminals are wired together.
amplifiednation wrote:Steve,
Congrats you solved the issue!!!
Great work man. I feel bad i was reluctant to do the swap but at least I learned something new!
Thanks man, PAB and ROCK are now their own switches!!!
Awesome! Now I feel better about moving forward on the build... I stopped right at the point of wiring the PAB.... I will probably do some work tonight.
At some point, one of us should ask jboarders to update the layout.
I just played through the amp a bit more...I may have spoken too soon.
I thought I was hearing individual differences between those two switches, but now I'm getting nothing from the PAB switch, and a boost when i put it into Jazz mode...
amplifiednation wrote:I just played through the amp a bit more...I may have spoken too soon.
I thought I was hearing individual differences between those two switches, but now I'm getting nothing from the PAB switch, and a boost when i put it into Jazz mode...
Taylor, if you are using an On/On/On switch for the R/J thats your issue. If you want to control the PAB from the front panel use a On/Off/On and wire it exactly like #124. The easier way to wire it is use a On/0n and wire it like the #183 scheme. These switches have a tendency to trick people up.
IIRC, it's been discussed that the wiring is backwards on the hybrid layout before.
