Per the subject line, if anyone might happen to have a clearly legible copy of subject schematic, I would appreciate receipt of same. LMK, and many thanks!! Tom D.
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Pilot 240 Integrated Amp - Schematic needed
- Thread starter Wharfcreek
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FlaCharlie
Super Member
Here's the full Sams in pdf, which can be enlarged to show detail.
Gents: Thanks! As I suspected, this unit has some rather 'unique' speaker connections associated with it. In looking at the schematics supplied, I see that the 4 ohm speaker tap off the OT is also that which is going to 'ground'. I believe Fisher did something like this as well. But, in the absense of any specific instructions on proper wiring, it leaves me wondering just how this thing ought to be hooked up? Looking at the Channel A speaker selector, it appears that the 4 ohm OT tap is run to a terminal on the speaker connection strip designated as 4 ohms. Not on this amp!! This unit appears to have 4 ohm connections to the speaker as designated by just using 'screws' to the chassis. The question is, if that is used as 'speaker positive', then where does 'speaker negative' connect? It looks like the center position wiper of the selector switch goes to the 'black' wire of the OT, which is 'normally' the 'speaker negative' wire. If so, then if I follow this through the switch diagram, it looks in the 'main speaker' position, the two connections would be: Positive speaker wire on the appropriate 8 or 16 ohm terminal on the strip, or just to the chassis, and 'speaker negative' would go to terminal on the strip designated as 'LFT' next to the 'main' designation. If using 'remote' speakers as well, those would also have the 'positive' wire hooked to the appropriate 8 or 16 ohm terminal, and the negative to the LFT or RT, but to the 'remote' contact vs the 'main' contact. Does this seem correct?
Gadget, look at the other schemo in post 2 from Openly bafled. Shows a different OT set-up with the 4 ohm tap going to what I believe to be chassis ground. I think that's what I'm dealing with. This is not my amp, but it's here just getting a 'refresh' to bring back to operational status. The chassis on this one has two screws that are both marked with '4' on them, and both in the area of the speaker terminals....and same 'print font' as the 8 and 16 ohm identification. Odd set up, but shown in that first schematic. I think the problem is the nomenclature on the speaker terminals......probably something PIlot did themselves. Not consistent with other, more commercially popular, ways of doing it.
trainbuftony
Electron Herder
I looked over the opt wiring on the schematic with the selector switch and 4 ohm taps chassis grounded. The 4 ohm tap is grounded so that the feedback signal can be taken from the black wire (usually ground)
It's not totally unorthodox, however most that I've seen ground one end of the opt secondary and take the feedback from the far end. (Usually the 16 ohm tsp) It's not carved in stone anywhere that feedback must be taken a certain way. It's one of those things where no consensus will ever be reached, and everyone needs to be ok with that.
I think if you have one set of speakers it's safe to hook them to the terminals corresponding to their ohm value.
If you want to run 5 channels they were up a switch to split left and right to 2 speakers each, and to derive a center channel, probably from the junction of the 0 ohm taps...
Seems real gimmicky to me, and I'd probably go ahead and just use one set of speakers connected to the correct tap.
Solid state amps that can drive multiple speaker systems always sound better, when they're not doing so.
It's not totally unorthodox, however most that I've seen ground one end of the opt secondary and take the feedback from the far end. (Usually the 16 ohm tsp) It's not carved in stone anywhere that feedback must be taken a certain way. It's one of those things where no consensus will ever be reached, and everyone needs to be ok with that.
I think if you have one set of speakers it's safe to hook them to the terminals corresponding to their ohm value.
If you want to run 5 channels they were up a switch to split left and right to 2 speakers each, and to derive a center channel, probably from the junction of the 0 ohm taps...
Seems real gimmicky to me, and I'd probably go ahead and just use one set of speakers connected to the correct tap.
Solid state amps that can drive multiple speaker systems always sound better, when they're not doing so.
Wiring the output transformers that way allows the use of a center channel speaker. 4 Ohms is the center-tap of the 16 Ohm winding, so the "C" and "16" terminals have equal signal with respect to ground (but opposite phase). A center channel speaker can be connected across "C" on one channel and "16" on the other - left and and right added in series. Sams schematic must be a different version.
so still basically the same hookup. Positive to whichever tap makes sense, negative to LFT main and RT main depending which side you're on.
ignore all of the rest unless you want to use the center channel or remote speakers. Also pay no attention to what is actually connected to the chassis. it'll still work as expected.
ignore all of the rest unless you want to use the center channel or remote speakers. Also pay no attention to what is actually connected to the chassis. it'll still work as expected.
OK, so I probably should have done this earlier, but the attached pic pretty clearly shows some of my 'confusion'. As you'll see on the speaker terminal strips, the connection to the left on both strips is marked as 'VIS'. I've never heard of that one, and don't know what it means. Likewise, the next terminal in line is marked as 'MOX' on the left strip, and 'ST+' on the right strip. Never heard of MOX, and can only guess as to how it corresponds to the ST+ on the other strip. Then each strip is marked with: "EX", "MA", "0", "8", & "16". Note that above the "0" is a round-head screw with the designation of the "4" next to it. So, assuming that no 'extention' speakers are being used, and that one wanted to 'properly' run any of 4, 8, or 16 ohm speakers, would the use of the terminal designated with the "MA" be the point where you'd connect the 'negative' speaker lead, and then connect the 'positive' lead to any of the designated 4, 8, or 16 contact points.....which would include using the chassis screws if using 4 ohm speakers?
This connection strip says nothing about a 'center' channel, and pretty clearly has the "0" point listed on it.....which is pretty commonly used as 'negative' by other manufacturers. But, I see a bit of a dilemma here as the "0" might be used for either the 8 or 16 ohm conections.......or not? Hence my desire to see the schematic. Unfortunately, neither schematic corresponds to what's on the amp. FUBAR!!!
This connection strip says nothing about a 'center' channel, and pretty clearly has the "0" point listed on it.....which is pretty commonly used as 'negative' by other manufacturers. But, I see a bit of a dilemma here as the "0" might be used for either the 8 or 16 ohm conections.......or not? Hence my desire to see the schematic. Unfortunately, neither schematic corresponds to what's on the amp. FUBAR!!!
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trainbuftony
Electron Herder
I think the 4 ohm terminal is chassis or ground and that speaker negative goes to 0
Speaker +goes to whichever tap is correct God that speaker.
+ in that case could go to chassis ground if a 4 ohm speaker is used.
I see no problem with that.
I'd get some speakers hooked up and running at a reasonable volume. Then without changing the volume, see what sort of AC voltage is on the strange unidentified taps.
Compare that to what is delivered to the speaker, as you cycle the speaker system selector through the positions.
Speaker +goes to whichever tap is correct God that speaker.
+ in that case could go to chassis ground if a 4 ohm speaker is used.
I see no problem with that.
I'd get some speakers hooked up and running at a reasonable volume. Then without changing the volume, see what sort of AC voltage is on the strange unidentified taps.
Compare that to what is delivered to the speaker, as you cycle the speaker system selector through the positions.
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