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Old 12th July 2010, 10:09 PM   #4131
NPower is offline NPower  Portugal
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Default Not solved

Quote:
Originally Posted by Salas View Post
Good luck. When you will solve the bug, the difference between psu's and the total quality will possibly go higher too.
Hello, today I get some spare time and I did some mod on phono PCB.
1º I tried a new reroute on IN and Rload ground (acc to Massimo)-same problem!!
2º I switch to old schematic (C1//D1-D4; R17 replaced by wire; Voltage on Q3 adjusted to 10V)-same problem!!
3º I removed all the protective varnish from the PCB-same problem
4º Put the pcb inside of a aluminium box-same problem.
After step one I took some measures.

Vcc-38.3V
Q1 D-6.75V G-0V S-0.156V Idss-9.15mA
Q3 C-10.25V B-7.4V E-6.75V
Q6 D-38.3V G-7.4V S-7.62V Idss-6.65mA
Q2 D-8.62V G-0V S-0.128V Idss-8.55mA
Q5 D-20.53 G-8.62V S-8.75V Idss-9.45mA

Also you can see some osciloscope pictures on Cout
First with PSu shunt reg, normal config
Second with R3 pulled from circuit

Any idea ???
Attached Images
File Type: jpeg comR4.jpeg (169.1 KB, 203 views)
File Type: jpeg semR4.jpeg (176.6 KB, 198 views)
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Old 12th July 2010, 11:03 PM   #4132
Salas is offline Salas  Greece
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Those are hum frequencies. Is it wired for signal input and output with coaxial? Also take out the 220uf over the leds and see if it has anything to do. If there is 0.1uf across B+ on phono take that out too.
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Old 13th July 2010, 02:25 AM   #4133
NPower is offline NPower  Portugal
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Quote:
Originally Posted by Salas View Post
Those are hum frequencies. Is it wired for signal input and output with coaxial? Also take out the 220uf over the leds and see if it has anything to do. If there is 0.1uf across B+ on phono take that out too.
Yes , it's wired, both with coaxial.Already removed 0.1uf across B+ and no change. About the pictures , when I connect the pre to amplifier with R3 pulled from circuit ( figure on right with 7.5mV stable sine ) I get HUM on the speakers with a much lower level. But, when I put it back,(R3).the output raises to aprox 11mV and becomes very erratic, mean, frequency,amplitude and shape of the wave are always changing. At that time is no more HUM, it's more noise (can't hear the HUM). Looks like the noise comes from Q1/Q3 themselfs. Tomorrow I will try without C1. Could be some problem with the jfets, I bought them from a guy in eBay/Taiwan.
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Old 13th July 2010, 03:28 AM   #4134
gjfim is offline gjfim  United States
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Originally Posted by Salas View Post
Hello

Make R7 1k. What is the idss of q5, and any info about the system it plays, photos?
Hi Salas- I will change R7 to 1K.

Idss of Q5 is 0.906ma (measured by 100R method).

system is Origin Live TT with Grado Master cartridge, ASKA preamp, F4 amp, single driver horn speakers (Lamhorn 1.8).

Thanks for your help.

Gary
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Old 13th July 2010, 03:34 AM   #4135
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Salas,
How far back in this thread do I have to go to get what is needed to build and inderstand this design? The size of this thread is daunting.

Thanks
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Old 13th July 2010, 06:17 AM   #4136
Salas is offline Salas  Greece
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Quote:
Originally Posted by NPower View Post
Yes , it's wired, both with coaxial.Already removed 0.1uf across B+ and no change. About the pictures , when I connect the pre to amplifier with R3 pulled from circuit ( figure on right with 7.5mV stable sine ) I get HUM on the speakers with a much lower level. But, when I put it back,(R3).the output raises to aprox 11mV and becomes very erratic, mean, frequency,amplitude and shape of the wave are always changing. At that time is no more HUM, it's more noise (can't hear the HUM). Looks like the noise comes from Q1/Q3 themselfs. Tomorrow I will try without C1. Could be some problem with the jfets, I bought them from a guy in eBay/Taiwan.
R3 disconnects the first stage if you take it out. So it comes from first stage.The voltages you posted are pretty OK.
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Old 13th July 2010, 06:24 AM   #4137
Salas is offline Salas  Greece
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Quote:
Originally Posted by gjfim View Post
Hi Salas- I will change R7 to 1K.

Idss of Q5 is 0.906ma (measured by 100R method).

system is Origin Live TT with Grado Master cartridge, ASKA preamp, F4 amp, single driver horn speakers (Lamhorn 1.8).

Thanks for your help.

Gary
9.06mA probably. R7 1k will suit it a bit lower than idss, a good thing. Nice system. Thanks. Let us know more when you will be playing along for some time. I wanna know if the 15.6n VS 16n is good in your opinion.
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Old 13th July 2010, 06:35 AM   #4138
Salas is offline Salas  Greece
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Quote:
Originally Posted by SGregory View Post
Salas,
How far back in this thread do I have to go to get what is needed to build and inderstand this design? The size of this thread is daunting.

Thanks
There is a pdf that member psgr made. It was hosted by Iko, don't have the link now, but pm me an email to send it to you. Its a bit big for the server's set limits. If you tell me more about your cart and the most available idss range in your njfet batch I will post you a more specific circuit.
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Old 13th July 2010, 07:00 AM   #4139
le´flu is offline le´flu  Germany
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Good Morning,

so i did match some 2sk170bl and got four pairs with idss 6,61mA.
Would you please recommend a circuit including salas-reg-psu to
me to ideally play with my lyra dorian cartridge as asked some post-
ings before.

Greetings Ulf
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Old 13th July 2010, 07:11 AM   #4140
Salas is offline Salas  Greece
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Yes I will do, since you have idss out of any range posted, is a must I look in to it. I will see exactly about Dorian.
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