F5X -- the EUVL Approach - The Build Thread - Page 29 - diyAudio
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Old 5th January 2013, 08:15 AM   #281
EUVL is offline EUVL  Europe
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I wasn't asking you to look up the values for all FETs you measured, though that should also not be so difficult.
I merely suggested that you could verify your figure of 63mV (or 125mV for that matter) from real measurement.

Bolts for the FETs you'll have to ask Mark.


Cheers,
Patrick
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Old 5th January 2013, 10:29 AM   #282
MarkLai is offline MarkLai  Hong Kong
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>Bolts for the FETs you'll have to ask Mark.
Yes, as far as I can remember for the bolt.
BUT, I did not include any spring/flat washers, sorry!
Mark
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Old 5th January 2013, 11:58 AM   #283
NicMac is offline NicMac  Italy
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>I wasn't asking you to look up the values for all FETs you measured, though that should also not be so difficult.

Easy enough

With Yfs equal to 4 Siemens it comes down to about 135 mV.

Each dot represents an individual FET (n = 1000+)
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Old 6th January 2013, 04:40 PM   #284
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So, after a log wait, I started again some activities on the F5X. My plan is the following:

1) Proceed channel by channel, right and then left.
2) Get the audio part working, then address the auxiliary functions. I may use a lab PS for this.

So far I completed the cap boards, the R boards, and I have all the passive components mounted on the amp boards.

So far I am addressing only practical/mechanical problems. Of course I have few questions and some findings:

1) Do we have to drill through the hole of the Mosfet to make space for the washer ? I think a 3.5mm bid is needed.

2) The amp boards need to be slightly filed on the side to properly sit between the cap boards.

3) I have the transformer with double primaries: is it worth to put a termistor between the primaries ?

4) For the connection of the DC to the amp boards, I understood that M4 screws to should be used. This can be avoided for the + and -, but not for GND. Any suggestion on where to find copper or brass M4 screws ?

More to come. Thanks,

Davide
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Old 6th January 2013, 05:48 PM   #285
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Patrick, Nick,
Quote:
Originally Posted by EUVL View Post
Dave please cross check.
I use square pads to designate pin one wherever possible in layouts. For the relay board - pin 1 of the diode is cathode and both pin 1 of the diode and relay were intended to be positive.

Quote:
Originally Posted by NicMac View Post
Ok. Removed the bipolar transistors, but also R13 and family.
The protection circuits should not affect the front end current without output devices installed... All measurements in the build article including the front end bias were done with the protection transistors and associated circuits installed.

Perhaps one or more of your protection transistors was bad? No ideas otherwise and I cannot make it act like the previous problem in the sim.

Hope it helps,
Dave
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Old 6th January 2013, 05:53 PM   #286
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Davide,

Glad to see more builds. Patrick can answer the mechanical questions and I believe he had a suggested source for a brass standoff for the center ground.

BOM update is still pending so make sure to double check once posted...
Dave
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Old 6th January 2013, 06:00 PM   #287
heinz1 is offline heinz1  Europe
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Quote:
Originally Posted by Nikon1975 View Post
....
4) For the connection of the DC to the amp boards, I understood that M4 screws to should be used. This can be avoided for the + and -, but not for GND. Any suggestion on where to find copper or brass M4 screws ?
...
I got my brass screws from this UK company:

Brass Machine Screws All Types - Page 4

Prices include registered shipping but not VAT.
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Old 6th January 2013, 06:14 PM   #288
NicMac is offline NicMac  Italy
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I used something like this from ebay. I have no idea if it is really copper.....
actually they say Brass in the item description.....

Last edited by NicMac; 6th January 2013 at 06:16 PM.
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Old 6th January 2013, 09:36 PM   #289
NicMac is offline NicMac  Italy
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Quote:
Originally Posted by Nikon1975 View Post
2) The amp boards need to be slightly filed on the side to properly sit between the cap boards.
I have plenty of space......
Are you sure you are not trying to mount the amp boards to the FET holes
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Old 6th January 2013, 10:30 PM   #290
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Click the image to open in full size.

Shouldn't be like this ?

Davide
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