Some 700 Series II Questions

mlucitt

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#1
Doing some research recently and found in the PL700II schematic, there are two Q110 transistors on the wall of outputs. Did that ever get resolved? Typo? Just curious.
Also, I saw this modification in the references. I don't know the source. Has anyone thought about this or tried it?

Finally, in the Clair Bros. PL700 amps that went to Hawaii, does anyone know the details of that story? And the control boards in those amps are designated "400/700 AMP BD"; were those made by PL for Clair Bros. or just a different board that used LF351N OPAMPs instead of the PL 36 boards that used the LF356 OPAMPs?

Phase Linear 700 Series II Mod.jpg
 
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#2
Mark,

My version of the 700II and 400II shows the Q10 error. I believe both manauls are latest revision. The rev level of your drawings is the same as mine. The 400 manual has service bulletins for the 700 which explains the opamp and update to full comp outputs. Those bulletins are not in my 700II manual.

I've never seen the proposed mod. It eliminates R128 and R130. These resistors are connected from the base of the output transistors to the amplifier output. On your drawing there are 2 dots where the resistors were originally shown.
 

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mlucitt

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#4
Do we know who made the transformers for the PL400 and PL700 amplifiers. I seem to remember reading some urban legends about this but does anyone know for sure? Ed...?

Mark
 

laatsch55

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#7
They are still in the transformer business..I believe it's the same Schumacher as Schumacher Racing in NHRA...
 

mlucitt

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#9
Yep, they'll wind you a new 700 transformer for $600
Schumacher probably has the same transformer core winder they used in 1970.
Say, while we're on the subject, do you have a picture or schematic drawing of how you install a switch to select 120V or 240V primary wire connections? I have this one, could it be adapted for PL700 Series II? Are the transformer wire colors consistent in the PL700 Series II?
Mains Selector Switch.JPG
 
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#10
Mark, you're drawing is correct. You would change the fuse to 10A for 120V. Where you put the switc h is another question.

In your post you mention core winder. I think you meant coil. In the late 70's I worked at a custom transformer shop. Hated every minute of it. Coils that used a paper form/corebox (vs nylon bobbin) were wound on a rectangular paper tube 24" long. The winding machine could produce up to 12 x 2" coils per tube. For the 700 xmfr they could produce probably 5 to 6 coils per tube. The only difference in making one coil or 6 would be the cost of copper. The labor cost would be the same.

Once the 24" tube is wound, then a person cut the coils on a bandsaw. The next department installed the leads. From there a semiautomated machine would install the core. The coil them got dipped in varnish and baked and then tested. The guy running the dip and bake room didn't wear a respirator and got high off the fumes most every day.

Assuming the process to manufacture is still largely the same, I would say that $600 for one xfmr is not all that bad. I could also believe the cost for 4 or 5 would be half that much.
 

mlucitt

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#12
Mark, you're drawing is correct. You would change the fuse to 10A for 120V. Where you put the switch is another question.

Assuming the process to manufacture is still largely the same, I would say that $600 for one xfmr is not all that bad. I could also believe the cost for 4 or 5 would be half that much.
Yes, I meant coil winder, not core winder. The coil winder winds the coils on the core which cores the coil so the coil is cored-HA!

Yes, the 120V fuse should be 10A, or 15A for extended listening at Lee Laatch levels. I think I want the switch near the terminal strip, so that I don't have to extent any of the transformer wires (I hope).
I found this AMF voltage selector switch:
AMF Voltage Selector Switch Front.jpg AMF Voltage Selector Switch Back.jpg
 
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