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Mark goes at it again... just bought a PL700/II!
- Thread starter MarkWComer
- Start date
My co worker has some L100s, damn fine speakers.
And revisiting Cerwin Vegas, I have some RE-25s I modified, I use in the shop with a Marantz 2230, thread on TH.
http://www.tapeheads.net/showthread.php?t=60441
Surrounds look orange to me!
And revisiting Cerwin Vegas, I have some RE-25s I modified, I use in the shop with a Marantz 2230, thread on TH.
http://www.tapeheads.net/showthread.php?t=60441
Surrounds look orange to me!
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- Victim of the record bug since age five
Interesting that the preamplifier "sees" the 100K sensitivity control impedance, the 220K resistor across the input jack is also "seen" by the preamp, and additionally the Control Board has a 39K resistor in parallel to the input that would be "seen" by the preamp. This adds up to just slightly under 25K for input impedance. (1/39K + 1/100K + 1/220K = 1/Rt) or (.00025641 + .00001 + .000004545 = 1/.000040186 or 24,884)
Yet, the input impedance is listed as 33K Ohms minimum in the PL700 II Service Manual.
By leaving out the 220K resistor across the input jack, the input impedance goes to (1/39K + 1/100K = Rt) or (.000025641 + .00001 = 1/.000030186 or 33,127 Ohms, or close to 33K Ohms.
Thoughts?
Yet, the input impedance is listed as 33K Ohms minimum in the PL700 II Service Manual.
By leaving out the 220K resistor across the input jack, the input impedance goes to (1/39K + 1/100K = Rt) or (.000025641 + .00001 = 1/.000030186 or 33,127 Ohms, or close to 33K Ohms.
Thoughts?
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I won't argue your calculations, but I see this resistor in several places of the original service manual as well as the documents from WOA. Looking at the SM, "33 k ohms minimum," so yes, it is out of line with that spec.
I don't see anything comparable in the schematics of the original driver circuit to that 39k resistor (whomever scans these manuals does NOT know how to use a scanner...).
If I have to re- edit this video, I'm gonna squirt chocolate syrup on yer french fries!!!
Is this the first that anyone has noticed this?
I don't see anything comparable in the schematics of the original driver circuit to that 39k resistor (whomever scans these manuals does NOT know how to use a scanner...).
If I have to re- edit this video, I'm gonna squirt chocolate syrup on yer french fries!!! Is this the first that anyone has noticed this?
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TWO QUESTIONS ABOUT THE CYLON CIRCUITS:
Pin5 = Analog ground. The Existing BLACK wire that originates from the amplifier chassis...
I think the instructions assume I'm replacing original cylons, not doing a complete rebuild. I have no black wire, I assume this instead is a wire coming from the neutral bus between the power caps.
Pin9 = B- Fused... Run 2 NEW purple wires from the shell (not the tip)...
Uhm... A typo? My route is this: from the B- PS cap to a common connection at the shell because at this point the tips bifurcate to L&R backplanes. If I connect to the shell, I'm B- UNfused. So, either way, is this a typo? Pin9 to unfused, or is shell/tip transposed in the document?
Pin5 = Analog ground. The Existing BLACK wire that originates from the amplifier chassis...
I think the instructions assume I'm replacing original cylons, not doing a complete rebuild. I have no black wire, I assume this instead is a wire coming from the neutral bus between the power caps.
Pin9 = B- Fused... Run 2 NEW purple wires from the shell (not the tip)...
Uhm... A typo? My route is this: from the B- PS cap to a common connection at the shell because at this point the tips bifurcate to L&R backplanes. If I connect to the shell, I'm B- UNfused. So, either way, is this a typo? Pin9 to unfused, or is shell/tip transposed in the document?
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Hi Mark
Raw unfused power should always go to the TIP (or end) of a fuseholder for safety reasons. That way the shell band of the fuseholder becomes dead when you remove a fuse from the holder. Remove a fuse from its holder and you can see that you can easily touch the shell band that is fully exposed. You do not want that to have a live voltage on it with fuse out. Thus the shell is the fused side of a power source and the tip is the unfused side of a power source. That is the convention that should be adhered to. PL did adhere to that in the PL400 fuse connections BUT violated that for the PL700s for wiring convenience purposes (they bent the two adjacent fuseholder shells over and connected one feed wire from the bulk caps through the joined shell connections). The instructions were written for the PL400. If you are putting into a PL700 then connect to the fused side. I will amend the instructions sometime in the future to cover both cases. You know by now that Phase Linear and consistency is an oxymoron.
Raw unfused power should always go to the TIP (or end) of a fuseholder for safety reasons. That way the shell band of the fuseholder becomes dead when you remove a fuse from the holder. Remove a fuse from its holder and you can see that you can easily touch the shell band that is fully exposed. You do not want that to have a live voltage on it with fuse out. Thus the shell is the fused side of a power source and the tip is the unfused side of a power source. That is the convention that should be adhered to. PL did adhere to that in the PL400 fuse connections BUT violated that for the PL700s for wiring convenience purposes (they bent the two adjacent fuseholder shells over and connected one feed wire from the bulk caps through the joined shell connections). The instructions were written for the PL400. If you are putting into a PL700 then connect to the fused side. I will amend the instructions sometime in the future to cover both cases. You know by now that Phase Linear and consistency is an oxymoron.
Mark, my Rev C Cylon instructions say the same thing. I believe the black wire on the original LED board comes from the terminal strip located between the left channel output transistor stacks and that's where the original PL chassis ground comes from. Joe has advocated the STAR ground, so this wire should now come from the neutral bus and go to Pin 5 of the RIGHT Cylon board only. Your assumption is correct, sir!
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Mark, you didn't do it wrong, PL did. Their engineers knew how to wire the Line and Load wires to a BUSS fuseholder, but the bean counters wanted to save $.03 on two feet of wire, so they bent the shell connections together and put 100VDC on them. Joe and I had this conversation awhile back. I turned my new fuseholders to a 45 degree orientation (easy to do in the new WOA chassis because the hole is round, not "D" shaped) and ran separate wires from the bulk caps to each fuseholder.
The amp will sound the same of course, you just need to be careful if you have to change a fuse with the Power turned ON. Wait, why would you do that? With the Power switch OFF, there will be no power at the fuse holder after about 2 hrs while the bulk caps dissipate their stored voltage. Are we having fun yet?
The amp will sound the same of course, you just need to be careful if you have to change a fuse with the Power turned ON. Wait, why would you do that? With the Power switch OFF, there will be no power at the fuse holder after about 2 hrs while the bulk caps dissipate their stored voltage. Are we having fun yet?
