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Old 26th July 2006, 10:21 AM   #11
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Question In rush termistor

Quote
it has a cl-60 inrush limiter with around 200,00 uf of caps.
it is essential ! you will smoke your power switch and probably the bridge rectifiers as well
Unquote

Sorry for my ignorance. What is a CL 60 inrush limiter ? Can it be bought somewhere ? Thanks for the kind advise
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Old 26th July 2006, 10:34 AM   #12
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Default Re: In rush termistor

Quote:
Originally posted by herodote

What is a CL 60 inrush limiter ?

It is a NTC thermistor.
It has a resistance when it is cold, resisting current flow.
But, getting warm, it loses the resistance, allowing the current flow.
Any make of around 10ohms/5A type is considered useful.
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Old 26th July 2006, 10:39 AM   #13
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Quote:
Originally posted by Nelson Pass

If you put a large cap across the bias transistor and reversed
diodes from the + and - of that cap to the output it will tend to
kill the turn on thump.

Another homework from Papa. . .
Hey, Zen, where are you? We need to do groupwork.

My first question:
C13 is already there across the bias transistor. Still, need additional cap across it as C13 is too small?
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Old 26th July 2006, 10:56 AM   #14
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Quote:
Originally posted by Babowana



Another homework from Papa. . .
Hey, Zen, where are you? We need to do groupwork.


sorry-ZM is this dayzzz in serious aka..........
no time and energy for puzzles ,unfortunately

it'll be better ,soon......
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
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Old 26th July 2006, 12:38 PM   #15
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Default Bias & kill the turn on thump.

When I measure the DC while starting the A40 amp it send to the loudspeakers a 380mV which then stabilize at 01mV

Could it be possible to know a bit more about what to do with the bias transistor (Q6) how to set up - as suggested by Nelson Pass - a large car (what value) and how to set up the diode. I don't understand how to connect the cap and the diode. Explanation would be welcome

I would like to understand N. Pass statement
If you put a large cap across the bias transistor and reversed
diodes from the + and - of that cap to the output it will tend to
kill the turn on thump.
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Old 26th July 2006, 02:48 PM   #16
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Quote:
Originally posted by Zen Mod

sorry-ZM is this dayzzz in serious aka..........
no time and energy for puzzles ,unfortunately

it'll be better ,soon......

O, wish you being fine soon. . .
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Old 26th July 2006, 04:36 PM   #17
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Default Bias & kill the turn on thump.

Sorry I should have been more factual about the whole story.

I had a DC offset of 40mV on both channel but no turn on thump. After adjusting resistor off collector Q1 (R6 - 680Ohms) the DC got to 1mV. I did make sure with R11 the bias of Q7+Q8 or (Q9,Q10) would stay at 1.5A. A turn on bump appeared. It measures 380mV at the start of the amplifier and then the DC settles at 1mV. Strangely the transformer is doing some hum... (new)

How do you wire a NTC thermistor ? Does is goes in serie on the primary input (220V) of transformer or between the secondary and the caps ?
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Old 26th July 2006, 05:30 PM   #18
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Default Re: Bias & kill the turn on thump.

Quote:
Originally posted by herodote

Does is goes in serie on the primary input (220V) of transformer?
Yes.
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Old 26th July 2006, 08:10 PM   #19
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OK
Attached Images
File Type: jpg a40thump.jpg (65.5 KB, 884 views)
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Old 27th July 2006, 02:49 AM   #20
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Quote:
Originally posted by Nelson Pass

OK

Your OK is a real short KO blow, . . .

Thanks!
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