Author Topic: newbie in QSXM2 , just received PCB  (Read 10605 times)

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Offline Edmund Chan

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newbie in QSXM2 , just received PCB
« on: November 11, 2009, 03:34:13 PM »
 :-D
I received your PCB, I need to start collect parts for that crazy Phono amp , in regards the number of components.

 :?
Can I replace the BC 550 and BC 560 with 2n4401 and 2n4403? I got some on hand.

 :?
I can download the QSXM3 parts list, couldn't find QSXM2, of course I can write it down one by one from your schematic.



Offline peranders

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Re: newbie in QSXM2 , just received PCB
« Reply #1 on: November 11, 2009, 04:41:10 PM »
Q1: The collector emitter voltage is just on the edge but it might work. The Hfe is a bit low, only 100. The C model I have used has 450 as min. You may have to recalculate some resistor values but I won't support this. The noise is also unknown, probably not an issue.

Q2: Notice that there are two pages of files. The BOM is on page 2, at the bottom.
/Per-Anders Sjöström, owner of this forum

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Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #2 on: November 12, 2009, 12:58:22 AM »
Thanks!
After register that forum, I can't log in to your sjostromaudio home page anymore??? don't know why. It was working yesterday.

Offline peranders

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Re: newbie in QSXM2 , just received PCB
« Reply #3 on: November 12, 2009, 06:43:59 AM »
Test now. You should have gotten an email from my Joomla system.
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Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #4 on: November 12, 2009, 12:23:59 PM »
heaveno sir, no mail from Joomla yet.
I keep trying to get the part list in order to start collecting parts.

Offline peranders

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Re: newbie in QSXM2 , just received PCB
« Reply #5 on: November 12, 2009, 01:11:02 PM »
I have sent you an email with PW. Let me know if you are msssing this also.
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Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #6 on: November 12, 2009, 02:33:36 PM »
I guess I miss that one too. Usually within minutes , right?

did you send it to chanedxxxd@net-yan.com?

Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #7 on: November 13, 2009, 12:54:11 AM »
 :lol:

I wild guess the last character of my password, believe it or not, it works. threre is discrepency from the one you sent me days ago.

Offline peranders

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Re: newbie in QSXM2 , just received PCB
« Reply #8 on: November 13, 2009, 06:30:07 AM »
I misspelled Chen-Chan.
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Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #9 on: November 13, 2009, 01:35:42 PM »
I will stick with BC550 and 560, they are easily available anyway.  I wonder how to read the part list of QSMX2,  Do I really need to get the 620 pcs componets accordingly?
Also, part list indicated that almost all resistors are 0.6W, but metal film resisitors are in sequence of  .25W, .5 W ..etc?

Offline peranders

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Re: newbie in QSXM2 , just received PCB
« Reply #10 on: November 13, 2009, 03:58:55 PM »
You should look at the schematic also. You should of course read what I have written. There you can see that I have alternative parts, mainly the transistors.

The resistors you see in the pictures are 0.6W which is the normal size. 0.25W metal film is really tiny and rather rare. If you'll find 0.5W it's also OK.
« Last Edit: November 13, 2009, 04:00:51 PM by peranders »
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Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #11 on: June 18, 2010, 09:13:55 AM »
I managed to solder all component on the PCB, just connected the + 18 v and - 18V to the board. It looks alright.
I have a stupid question.
What is the function of the two LED on each channel, does it must be red LED. Should I use yellow, green....e.tc.
When it powered on, on channel with both LED lit on, the other channel does not.
Is it normal??

Offline peranders

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Re: newbie in QSXM2 , just received PCB
« Reply #12 on: June 18, 2010, 11:38:23 AM »
The LED's serves as a 1.6V reference for the output stage and they should be lit.

The one who is not lit, have you mounted it right?
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Offline Edmund Chan

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Re: newbie in QSXM2 , just received PCB
« Reply #13 on: June 18, 2010, 02:35:14 PM »
 :-DI am sure the LED polarity is correct.  :-D

When I powered on the to the circuit board, H1 lit on for 1-2 seconds, and turned off. H2 brigthness is very weak, can barely see the light.
Then H3 and H4 lit on no problem.   I just connect the power to the circuit baord, havem't connect the cartridge to the input yet. Will be test with my turntable in next few days.
 :?

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Re: newbie in QSXM2 , just received PCB
« Reply #14 on: June 20, 2010, 05:38:22 PM »
Since both LED's on the right channel don't work you must check all current generators. Start with DZ12, E8. E10 and move towards right. The goes for the upper half with DZ11. You all voltages written down at my webpage.
/Per-Anders Sjöström, owner of this forum

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