Derek92994's 700 Ser II White Oak conversion

laatsch55

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Is there a resistor on the light board we can replace to drop the input voltage?
 
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laatsch55 said:
Joe, have you ever measured the display voltage on a Ser II?
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Which one, Lee? B+ (after rectification and filtering by the right (I think.. one of the two) board).. or AC in from the xformer (same as normal.. 8 vac)... or do you mean input sensitivity for full scale?

B+ would be.. errr. about 6.3 volts.
 
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Jer, the LED displays have some IC's in em. I'm thinkin they might be 15volt? or 8 per side?
 
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laatsch55 said:
Jer, the LED displays have some IC's in em. I'm thinkin they might be 15volt? or 8 per side?
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Closest I came is the UAA 170, which seems about right. It takes 12 volts. Hmm.. maybe not 8 volts on the secondary then. Hey I wonder if Doug can measure his for you? The two ac lines are fairly accessible.
 
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laatsch55 said:
IC's look to be a UAA170....
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Great minds... LOL.

Yeah, about 12 volts dc. Hey.. heck man.. feed it with a variac, and while you are watching both the DC output (should be the red wire that goes between the two channel displays not the right channel from the amp) and the led's dial it in for 12 volts DC for B+
 
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jbeckva said:
Great minds... LOL.

Yeah, about 12 volts dc. Hey.. heck man.. feed it with a variac, and while you are watching both the DC output (should be the red wire that goes between the two channel displays not the right channel from the amp) and the led's dial it in for 12 volts DC for B+
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forgot to add.. and then measure the variac's ac output and there you go.. that should be the secondary's output
 
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There weren't any displays shipped with it. It was minus the faceplate, so we're going with a B faceplate and light board...
 
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The transformer is in Australia. It's a SerII transformer. There was no faceplate. I am converting the amp to a B. I am going to power this with an external power supply to verify the build. D2 will then install and wire the transformer when he gets it back...
 
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I can measure mine if you let me know what exactly you need measured. I expect the Pro transformer voltage output should be the same as a Series II. It uses the same PL37 display board at any rate.
 
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The transformer taps will be on the terminal strips where they join the wires running to the meter board.
 
derek92994

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Sounds good, I do have a multi meter, I'm sure that we will figure this out. I like the look of 700 B face plates too, very retro.
 
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I need more info re the white oak boards, and what makes them better than the standard boards that PL made. As much info as possible please or direct me to a thread where I can find this. A friend of mine wants to know more about what has been done to the boards. Also are the same output transistors used? I assume you are using different ones now which are better. Is there a bridge Rectifier or power supply diodes involved, and have they been upgraded was another question I was asked.
 
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laatsch55

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D2, everything has been upgraded. We now use 50 amp bridge rectifiers, the outputs are the finest made nowadays, wayyyyyyy better than the originals. They are quieter, cleaner and much more reliable..

There is so much that has been changed it would take a day to tell you...
 
derek92994

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laatsch55 said:
D2, everything has been upgraded. We now use 50 amp bridge rectifiers, the outputs are the finest made nowadays, wayyyyyyy better than the originals. They are quieter, cleaner and much more reliable..

There is so much that has been changed it would take a day to tell you...
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What are the output transistor types?
 
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