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Old 26th February 2013, 01:14 AM   #1981
Salas is offline Salas  Greece
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So change the jfets also bcs a gate could have been hit back then.
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Old 26th February 2013, 01:33 AM   #1982
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Your c7 and c9 are double checked they are identical right values between channels?
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Old 26th February 2013, 02:10 AM   #1983
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Yes. Just checked. They are correct, identical to good channel.

Also, I was testing all the ground points on the circuit, doing a continuity test from the psu input ground pad and I found a few issues. C3 ground pin was not soldered properly. Input ground wire was not soldered properly. Repaired. Hum has gone way down, only slight hum with volume fairly high, probably because of how it is rigged on the bench.

Still have oscillation problem at R16/R17. I will give it a break and swap Q4, Q5 tomorrow.

Thanks for the help.
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Old 26th February 2013, 02:11 AM   #1984
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Old 26th February 2013, 06:16 AM   #1985
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Quote:
Originally Posted by Itsmee View Post
Start at the beginning, the voltage around Q3 is wrong, once sorted move on to the hum problem.

In Wayne's circuit the JFET's are drawing 20mA, bnorrish your circuit is drawing 28mA, adjust the value of R9 to 330R or 360R to compensate 10V/0.28mA=~360R.

Seberia has the same problem.

Do you have hum at the collector of Q3?
Didn't Wayne mention way back in this thread that R9 was part of the RIAA network and should be left alone?

Can higher Idss of the quad at the input really have much impact on the second stage? I have no audible problems with mine, I'm only having a bit of trouble with the 0V dc setting (mostly the right channel). I can get it to wander fairly close around 0V, but if you measure again next day miost of the times it has wandered off, to something like 300mV (I power down the unit at night btw, only measuring after it has been on for at least an hour).

Changing the 10R to 12R would get my quad down from 27,5mA to 23mA, 15R would get it to 18,5mA. But if this lowers the gain of the first stage I will have to compensate that in the second stage as I like a bit more gain than the standard 55dB.
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Old 26th February 2013, 11:31 AM   #1986
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Make sure to buy her some nice records to keep her interested. Joni Mitchell, Carole King, Cat Stevens in my case.
Ha, if only--for my wife it would have to be Tool, and their vinyl costs a mint. It would make her happy, though, so I will probably do it.
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Old 26th February 2013, 12:12 PM   #1987
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Originally Posted by jhsjhs99 View Post
Ha, if only--for my wife it would have to be Tool, and their vinyl costs a mint. It would make her happy, though, so I will probably do it.
Your wife is coooool and I'm jealous!

PS You better hold on to that one! She's a keeper!
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Old 26th February 2013, 01:54 PM   #1988
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I know, I am lucky. She took me to see Tool when she was 8 months pregnant with our first child. He is only ten months now, but thankfully seems largely free of angst. We will see.

Hi folks. I have decided to give this a try, and have begun to order parts. I am a genuine beginner--my only electronics experience up to this point came from owning an Italian motorcycle, whose electrical system was (predictably) crap, and fried. I taught myself to solder and got it back on the road, but it was more just following instructions than genuinely understanding what was going on (lots and lots of info out there on fried Italian motorcycle electrical systems). I have bought a few "learn to solder" boards to practice on, and hopefully will get comfortable with it when I have the parts to begin.

I am planning to start with the power supply, and following the example of budwiser, as pictured in post 1387 and discussed in post 1480. I am trying to map the power supply design to the schematic, and have a few questions right off the bat. Some are very basic, for which I apologize.

In reference to the following picture: http://www.diyaudio.com/forums/attac...9-22.59.04.jpg

Am I thinking of this right: what I see is the connector to the power cord on the bottom left, with the pink cable going up to the power switch, which is connected to an LED (?not sure of this?), which is connected to the fuse on the schematic (?). This is connected, along with the black wire, to C1 (?).

First really dumb question: why do the red and black wires actually have two wires (besides that is what comes with the transformer)? How do you know which wire to hook up the capacitor to?

Small question: in this picture, what is the little thing called that allows you to make four connections, bolted to the case (it makes the wiring neat, I haven't been able to find one because I am not sure what it is called): http://www.diyaudio.com/forums/attac...9-22.58.43.jpg

Last questions (for now, I imagine!): does it matter whether you use male or female jacks for the XLR? Can someone suggest a similar case?

Thanks very much for any responses, and thanks for all the work you have done communicating on this topic. I would never try this if not for this thread. Just so you know, I am looking to replace a Phonomena with this, and have a Lyra Dorian cartridge.

Thanks again!
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Old 26th February 2013, 03:43 PM   #1989
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As far as I can reply: on the left is a switch I think. Red wire comes from the mains socket, goes to the switch and the pink wire (=overexposed red) then goes to a fuse. A small black capacitor (3.3nF) can be seen from black wire to the fuse. This capacitor is also in the PSU schematic in the Pearl II article. Two red and black wires probably because of 2 120V windings from the transformer. No LED, the LED will be powered by the DC voltage of 28-35V (and protected by a resistor)

Male and female jacks: choose male for the jack/chassis part that does not carry voltage when you can touch it. So the mains input on the PSU chassis can be male, the mains jack on the mains cable then is female, or you would be in real danger of electrocuting yourself. The DC out chassis part (PSU) is female, the DC in chassis part (on the Pearl II) is male, cable plugs for the DC cable of course the opposite sex from the chassis parts...
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Old 26th February 2013, 04:36 PM   #1990
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Thanks very much, particularly for the male/female jack point, which now that you say it sounds obvious. I would have been embarrassed to electrocute myself on the first project. Re: the rest, I am pleased I got so close, and appreciate your clarifications.
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