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Old 3rd December 2011, 05:01 PM   #1081
nar is offline nar
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Maybe it's turn on thump - with 2 boards and such a capacitance onboard, it could be inrush

Did you try with 1A slow blow fuse ?

Best,

nAr
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Old 3rd December 2011, 09:42 PM   #1082
6L6 is offline 6L6  United States
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nar - That is a very good observation! I didn't think of that! The inrush with those big caps will be pretty big, on top of the the 30,000uf on each board...

Rich - give that a try. Use a one amp slow and see if it stays on. Measure your voltages at the RIAA board power inputs as well as the regulator outputs.
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Old 3rd December 2011, 11:36 PM   #1083
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I'll try the 1 amp slow blow fuse ,but the caps are 10000 uF not 15000 uF .... Ok I'm getting 24.50 post regs with the 1 A fuse ... Time lag , I guess Lag = Slow ?

Wheres the RIAA board input ?

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Old 4th December 2011, 03:52 AM   #1084
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The RIAA board input is just where the PSU board hooks up to the Pearl circuit boards. RIAA board = the two green ones. (But you know that)

I'm curious what the voltage is at the input to the Pearl boards, I.E., before the regulators, but under load.

And just to confirm, you have both boards hooked up, and the 1A fuse is holding?
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Old 4th December 2011, 07:04 AM   #1085
nar is offline nar
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Quote:
Originally Posted by 6L6 View Post
And just to confirm, you have both boards hooked up, and the 1A fuse is holding?
That's just what we want to know
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Old 4th December 2011, 11:03 AM   #1086
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Both boards @ RIAA input 39.6 VDC with 1 A fuse
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Old 4th December 2011, 02:16 PM   #1087
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Quote:
Originally Posted by richluvsound View Post
Both boards @ RIAA input 39.6 VDC with 1 A fuse
So it works ? What type and size (VA rating) of xformer are U using ? I couldn't see it on the pics you previously posted.

Basically, I would recommend using 2 thermistors CL-60 in series with primary winding (mains 230V) so maybe after that you could try to lower the fuse value, and see if it powers up still without blowing @ 500mA

Next step ? rewiring ground scheme if you have audible hum ?

Each Board must have its own Ground wire from output Ground of PS. Then, if noise still, it can be reduced; 100nF can be put between floating RCA GND input socket and case ( which should be directly connected to Earth pole from Mains).
This often does the trick to achieve quiet operation.

Wasn't needed on the UGS pre, nor on Pearl II but on my new freshly mounted Aleph_J it worked wonders and totally cured the hum. I thought it was residue from CRC, was wrong; now the bloc is dead silent, only music out, no more noise

Best,

nAr
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Last edited by nar; 4th December 2011 at 02:25 PM.
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Old 4th December 2011, 02:17 PM   #1088
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Quote:
Originally Posted by 6L6 View Post
nar - That is a very good observation! I didn't think of that!
lol np with that

Best,

nAr
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Old 4th December 2011, 02:35 PM   #1089
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Nar,


I will add another ground wire as you suggest

Transformer is 24-0-24 50va ... from farnell

All fets test good as new .

Is there a similar test for 450 and 3310 ?

Could you draw a little sketch of the CL60 on the mains you suggest please ?

Things sink home for me visually

Best , Rich

Last edited by richluvsound; 4th December 2011 at 02:38 PM.
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Old 4th December 2011, 03:15 PM   #1090
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