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Old 1st September 2008, 03:38 PM   #571
CeeVee is offline CeeVee  Portugal
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Hi Maousse,

I ground the inputs at the UGS module input connector to the ground at that connector.

I was in a bit of a rush yesterday but i will have another slow look today, that mute relay i will look at.

Logic being, that since display logic drives both MB in parallel, then if one works the other has to as well.

malfunction can only be in the cable to MB or MB itself.

I exclude the cable because if i disconect logic cable to the other ,working, channel i can hear relays comuting input selection and volume settings....and yes i have tried diferent inputs with same result.

That mute relay is a must to try....we will see.
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Old 1st September 2008, 03:41 PM   #572
Maousse is offline Maousse  France
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Quote:
Originally posted by CeeVee
Hi Maousse,

I ground the inputs at the UGS module input connector to the ground at that connector.

I was in a bit of a rush yesterday but i will have another slow look today, that mute relay i will look at.

Logic being, that since display logic drives both MB in parallel, then if one works the other has to as well.

malfunction can only be in the cable to MB or MB itself.
About the UGS module's connector :
I did the same, female connector on one end, male connector on the other end, but I kept the same order for the two modules.

Talking about the RV, sorry, the last CheffDeGaar's schematic is changed for both 50R, it's better
So just forget that part of my words :P

So, with both inputs grounded, turning either pots do change offsets ? Just to be sure one of the pots are not jammed.

OK for the mute relay voltage. The C command is amplified on each motherboard with the switching darlingtons, so one may be dead. Please, DONT measure directly the C ouput, as it may kill it. By measuring the coil command voltage, we see at the end of the chain if there is a problem, then we will go upward the command signal, step by step.
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Old 1st September 2008, 03:46 PM   #573
CeeVee is offline CeeVee  Portugal
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Both pots in UGS module are now 50 R ?

...I have one 20R ( absolute offset ) and one 50R for relative offset.
even so...250mv is a BIG offset, the explanation has to be another one.

Yes i hear you ....don't touch the ATmega if you can, i will measure at the sharp end......at the relay.
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Old 1st September 2008, 03:50 PM   #574
Maousse is offline Maousse  France
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Quote:
Originally posted by CeeVee
Both pots in UGS module are now 50 R ?

...I have one 20R ( absolute offset ) and one 50R for relative offset.
Huh.... Sorry, just reading fast on the first post , and only the first design schematic has two 50R RV. So my remark still has sense.
Just be sure you didn't swapped the 50R and the 20R

And looking for the problem, I ask you to check also all the resistors. One may be at the wrong place, so wrong value. Look around the 50R RV, aka Rs1 Rs2 Rs3 Rs4
Click the image to open in full size.

But first, I would like to know if the 50R has some action and is not jammed (it can happen). In that case, of course, you cannot adjust relative offset.
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Old 1st September 2008, 04:00 PM   #575
CeeVee is offline CeeVee  Portugal
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The pot does have action....250mv is the lowest i can get to.....but it does go up....and how !!!
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Old 1st September 2008, 04:04 PM   #576
Maousse is offline Maousse  France
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OK, are you at home ?
Can you check if the 50R and the 20R are at their right place?
A close picture of the faulty module may help. If you cannot make macro photo, just try to use a flat scanner, it may help
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Old 1st September 2008, 04:08 PM   #577
CeeVee is offline CeeVee  Portugal
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No I'm at work, will get you details and picture later,

thanks

It's not long now that i will have beautifull UGS sound.....for my Orions.
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Old 1st September 2008, 04:09 PM   #578
Maousse is offline Maousse  France
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Yes, it will be a real pleasure
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Old 1st September 2008, 04:12 PM   #579
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Hi CV
Sorry for delay, but I have to do real work sometimes...
Thanks to Maousse and Manu for being so quick and helpful in the meantime

Concerning the "big" abs offset, what is the JFets grade of this module ? BL or V ?
If they're "V" grade, you should try to increase degeneration resistors to get down to 3.5mA bias current in the JFets.
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/Cheff - Falling feels like flying, until you hit the ground
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Old 1st September 2008, 04:16 PM   #580
CeeVee is offline CeeVee  Portugal
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Hi Cheff,

There is a great team here....ofcourse the band leader is always a pleasure to hear!

My Jfets are BL ....still have a dozen or so of each.
I'm inclined to a stupid mistake...like a wrong value resistor, will check.
my bias current if i remember correctly, i'm at work, is arround 3.2mA.

Thanks
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