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Old 9th April 2013, 04:43 PM   #71
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FormosaWest Your getting some very good advice. Good to explore ideas and learn but there is such a thing as analysis paralysis. I second 6L6 -build it stock first. You need to know what's in the box to be able to think outside the box.
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Old 9th April 2013, 05:12 PM   #72
Mr. dB is online now Mr. dB  United States
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Quote:
Originally Posted by 6L6 View Post
You do realize that the single biggest thing that makes the Pearl so quiet is that fact that you can place the PSU box 3 or 4 feet from the RIAA box... (And that it has more PSU capacitance than some power amps...)
How much of that advantage is lost, then, if you proceed to place the Pearl next to a line stage preamp with an internal transformer?
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Old 9th April 2013, 06:13 PM   #73
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Some, certainly. The trick is to get the Pearl RIAA as close to the turntable as you can.
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Old 14th April 2013, 04:59 AM   #74
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Originally Posted by kmo98 View Post
Can you tell me what the pcb dimensions are?
Thanks
I *think* they are 5x7 .. mine havent arrived yet though
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Old 14th April 2013, 06:19 PM   #75
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Originally Posted by 6L6 View Post
Some, certainly. The trick is to get the Pearl RIAA as close to the turntable as you can.
..then it will be close to the TT motor, and PSU. just kidding..
I'm waiting for my Pearl Two boards, and pondering to feed them with a Salas shunt supply, taken from Mezmerize pcb. A great combo, i guess
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Old 14th April 2013, 06:24 PM   #76
Mr. dB is online now Mr. dB  United States
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Originally Posted by FormosaWest View Post
I *think* they are 5x7 .. mine havent arrived yet though
Yes, 5" x 7".
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Old 6th May 2013, 09:35 AM   #77
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So I'm pleased to say I've completed the power supply for the pearl, and a bulb tester (as per directions on decible-dungeon). Im very proud of my first diy so far!
I think i might be having some issues though.. Im hoping its all benign troubles. Can anyone chime in with some Help ... Ive blown both of my fuses.. And will need to buy more.. But before i start blowing more fuses and money... Could i borrow your expert minds to help me sort it. I wonder, Could tripping be due to power up surging as the caps fill up?? Im using 2 x 6800uf LAO series caps per rail with small wire-wound resistors for a crc layout. I have an led on the positive rail to indicate power. There is a bleeding resistor across the second cap of each rail. No snubbing caps installed.

First things first.. So. Im blowing fuses basically right away. The first one lasted about 20 seconds.. Just long enough to see that the voltage on the dc was around 14 or so.. With a 40 watt bulb in the tester. The bulb didn't dim completely, but did run quite dim. It never stopped burning untill the fuse blew. As soon as i hit the by pass to see if the voltage would climb to the target 36v the bulb went out and sure enough it was the fuse - it couldnt handle full power.. I didn't manage to test the ac voltage after the transformer.

The second fuse blew before the bulb would even fire up. So the bulb never lit uo. They were 500mA 250v not sure if they were slow or fast types. Alll the diodes and the measure the same in the diode test.1.8 for the led and 2.4 for the schottkeys if i recall. There is continuity between + and - rail ,... Im guessing thats because of the bleeders....? Ground is on the chassis side of loop breaker.

Transformer is shielded and centre tapped.

+Gnd is wired to Crc bleeder and led was wired point to point on a plain prototylpe board. Diodes are on Peter Daniels board. No snubber- caps yet.

Thoughts? Why the fuses dlowing
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Old 6th May 2013, 12:27 PM   #78
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You probably have one of the transformer windings out of phase.
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Old 6th May 2013, 02:06 PM   #79
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And/or you have fast-blow fuses. A slow-blo will have a T or S near the current rating, for Time or Slow

I.E.,

250V 0.5AT or 250V S0.5A You get the idea. On glass fuses the T is more common.
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Old 6th May 2013, 03:08 PM   #80
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The transformer is an R-Core and is wired as follows:
1) Two red wires on "110v" primary (Wall voltage is 118v.) wired to switch with xtype capacitor across the live side.
2) One green/yellow wire that the diagram shows to come from between the windings and is labelled with a ground symbol (i understood as a shield) so i wired that to the chassis, bypassing the loop breaker. The transformer is mounted to the case on rubber bushings. There is continuity between the metal base of the xformer and the IEC ground pin.
3) Two white and one black on secondary side. The secondaries are wired to a peterdaniels gain-clone diode board like this:

+ White.
G+ Black *
G- Black(jumped*)
- White.

*Since there was only one black i patched the two zero lines together w a short wire jumper. I found it difficult to find info to confirm that this is correct as most people have dual secondaries.

The loop-breaker is a 35amp rectifier bridge with ~ and ~ shorted, + and - shorted, and a y2 type capacitor and 10ohm resistor parallel across ~ and - (as per diagram on decimal dungeon and article avoiding ground loops)

Last edited by FormosaWest; 6th May 2013 at 03:24 PM.
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