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Old 26th September 2009, 04:28 AM   #1
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Default RCA Calypso

I got this console in non-working condition (bad caps). The attachment is an approximation of the circuit ( I omitted the balance, tone and loudness). Any thoughts on the schematic?
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Old 26th September 2009, 05:29 AM   #2
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Other than the plate-to-plate feedback,it looks pretty standard to me. Should make a handful of watts.
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Old 26th September 2009, 06:51 PM   #3
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Sorry, but where is the grid resistor /to ground/ of 6BQ5?

Last edited by azazello; 26th September 2009 at 06:54 PM.
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Old 27th September 2009, 01:42 AM   #4
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Originally Posted by azazello View Post
Sorry, but where is the grid resistor /to ground/ of 6BQ5?
There wasn't one...
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Old 27th September 2009, 03:37 PM   #5
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OK....I'm sure that RCA is right!
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Old 29th September 2009, 07:39 PM   #6
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OK....I'm sure that RCA is right!
It didn't seem anybody messed with the original circuit... The fact that the resistor is not grounded was the main reason for my starting this thread: while I'm not totally new to 'toobs', I'm still light years away from being able to understand all the nuances (doing the math, etc.)...
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Old 29th September 2009, 09:15 PM   #7
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Hum,I didn't catch that on my first glance.
It seems for sure that there should be a grid-leak resistor to ground,or else the bias point will drift at the least,or go into runaway at worst. Strange.
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Old 30th September 2009, 02:32 AM   #8
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'Mystery' solved - thank you guys. You persuaded me to double-check the (complete) circuit, which I did and... The grid resistor IS grounded - through the balance pot... Oh well, another lesson learned...
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