700B blew one Right channel 5A supply fuse

Left Q4
B: + 8.88 volts DC

Left Q5
B: -61.20 vots DC (minus)

Right Q4
B: +24.45 volts DC

Right Q5
B: -61.1 volts DC (minus)
 
Check voltage on each side of R8 on the right channel then compare to the left channel..
 
Left R8
9.93 volts AD and 61.5 volts DC

Right R8
25.64 volts DC and 62 volts DC

Just had a mishap. Looks like the trace from B+ touched ground and sparked. Unplugged the amplifier ASAP and moved board out of the way. Plugged the amp in again and smoked (literally) Left channel R2.
 
Power the amp down, bleed the big caps and check Q1 in that channel. Going to bed Gary, wde'll pick up where wew left off...
 
62vauxhall said:
R1 on the left channel is by itself but R1 left channel has another resistor piggybacked in parallel. Can't identify it's value because it's got 6 bands and I don't know which color band the code starts with.
Click to expand...

What are the colors of the 6 band resistor? (Any order, forward or reverse.)
 
laatsch55 said:
Did you check fuses?
Click to expand...

Yes, immediately after it shorted.

R2 is a 56 Ohm which I don't have so will leave soon to get a replacement, store opens in 1 1/2 hours. Unfortunately about a two hour round trip with morning traffic.

Odd that Left channel R2 is 56 Ohms and Right channel R2 is 2.7 Ohms.
 
Elite-ist said:
Is this you, Gary?



Nando.
Click to expand...

No, that's not me.

This is:


1897670_1421682118088601_685386252_n.jpg



I see I was not the only one to get hardware signed. Whoever that is has an amplifier that weighs considerably less than a 700B. All I wanted to carry was the face plate. I brought my own Sharpie and waited outside until he got there.

Should have waited maybe until he started using gold inK - might have been a bit more aesthetic.

Phase Linear 700B signed faceplate 1.jpgPhase Linear 700B signed faceplate 2.jpgPhase Linear 700B signed faceplate 3.jpgPhase Linear 700B signed faceplate 4.jpg
 
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That's one of the first questions I'm goung to ask Bob....Ed has old me a story on that. Seems Bob was putzing around one day and suddenly shut down the line and said R2R was going to be 56ohm instead of 2.7ohm because it sounded better....
 
Thanks Gary, nice to put a face to the typin....

Could be your brother though...
 
Not that critical, anuyhing between 2 and 56 is fine....3.3, 5.6, 10, 12, 15, 18, 20, 22, anything....
 
All R2 does is float the input slightly above ground potential
 
Damn, trying to make it easy on ya , but you make it so hard....:-o
 
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