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Old 2nd September 2008, 01:37 PM   #591
CeeVee is offline CeeVee  Portugal
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Hi Maousse, Manu,

I did take pictures, have them with me at work but i don't know if i will have time today....have work to do...lots of it !

I will put them up today, probably late, as for the info, you bet i will keep you guys informed, i know that this info might be usefull to others.
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Old 2nd September 2008, 10:22 PM   #592
CeeVee is offline CeeVee  Portugal
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Ok i promised some pictures today, so here goes;

Solved the "dud" issue.
After measuring the whole board it became quite clear something odd was going on arround the K389.
Taking a closer look at what i thought i had looked at many times, i saw that there was a cut track connecting the fb resistor to the connector.

Fixed that, tested and put it playing after aligning the offsets....it sings.

This just goes to show that one can look and not see what is in front of us .

Tomorrow, more pictures and some results, i hope of the tests Cheff and Maousse sugested.
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Old 3rd September 2008, 08:10 AM   #593
Maousse is offline Maousse  France
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Hi, glad you've made it.
Nice work
So it was the PCB...

I'm so confident in PCBmakers that I don't think about testing the fab quality

Where do your PCBs come from? Is it the last french GB?
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Old 3rd September 2008, 08:54 AM   #594
CeeVee is offline CeeVee  Portugal
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Hi Maousse,

Yes..last French GB...i was the one who pointed you guys to the Czeck republic for good "cheap" PCBs......if it's good enough for Pavel Dudek.....
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Old 3rd September 2008, 11:12 AM   #595
Manu is offline Manu  Europe
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Quote:
Originally posted by CeeVee

Solved the "dud" issue.


Thanks for reporting.
And thanks for having had this issue - so to speak ...
Half serious : Its always very interesting ... Thats sharing experiences ... which is precious.

I suppose you did the first tests with the FB res not implemented. And all readings were OK. So you couldn't see the problem.
So I think it could be usefull in the future to test the boards a 2nd time with the FB res in to be sure...

BTW Which is the value of Rin you choose?

Manu
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Old 3rd September 2008, 11:21 AM   #596
CeeVee is offline CeeVee  Portugal
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Hi Manu,

Yes the document published by François is very thourough but as he states near the end...it does not cover everything.

The feedback resistor is only put in at the end before offset adjustment, odd thing with this board was that the offsets adjusted ok before but what was clear after a complete check on all the bias points was that the gate values were crazy.

This is the clearest sign that the feedback resistor was not ok but this was a test that was not included in the paper...we can include it now i guess

Now i will try to debug the other board, wich plays but does not adjust absolute offset.
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Old 3rd September 2008, 01:48 PM   #597
CeeVee is offline CeeVee  Portugal
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After lunch Reply;

Rin is 15K in my case.
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Old 4th September 2008, 09:12 AM   #598
CeeVee is offline CeeVee  Portugal
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Yesterday had no time for debugging....life !

But there is an issue i'd like to share, in the past few days i've been doing A/B comparison tests with DACs, using the UGS ie: input 1 - my Shanling CD, input 2 Shanling but with diferent DACs.

Should be easy just swapping between input 1 and 2 ...but i notice that not always does the switching occur, sometimes i need to repeat the procedure for the relays to actually switch...there seems to be some lag, have any of you experienced this ?
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Old 4th September 2008, 10:44 AM   #599
Maousse is offline Maousse  France
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Well, no, not for the few UGS I had or tested.
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Old 4th September 2008, 12:29 PM   #600
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Quote:
Originally posted by CeeVee
Yesterday had no time for debugging....life !

But there is an issue i'd like to share, in the past few days i've been doing A/B comparison tests with DACs, using the UGS ie: input 1 - my Shanling CD, input 2 Shanling but with diferent DACs.

Should be easy just swapping between input 1 and 2 ...but i notice that not always does the switching occur, sometimes i need to repeat the procedure for the relays to actually switch...there seems to be some lag, have any of you experienced this ?
Hi Calrlos,

Never encountered your problem...

Normal sequence of relays when switching from input A to B :
1) Mute relay on (muted output)
2) Signal relay for A off
3) Ground relay A off
4) Ground relay B on
5) Signal relay B on
6) mute relay off to get sound again.

All of this within 2 seconds

Does your problem happen both when using the switches or the remote ?
Same symptoms with input 3 & 4, or 1 & 3 for instance ?
The two channels show the same behaviour ?

You've checked your ribbon cables/connectors ?

Sorry to see you collecting so much probelms....
__________________
/Cheff - Falling feels like flying, until you hit the ground
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