Mezmerize DCB1 Building Thread - Page 53 - diyAudio
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Old 28th April 2012, 03:30 PM   #521
Salas is online now Salas  Greece
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Wire the case to middle trafo connector's screw to see if it can help as much as it may regard the buffer.
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Old 3rd May 2012, 03:37 PM   #522
n00b is offline n00b  Germany
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Hey guys!

I just finished my Mesmerize. Here's a pic:

As you can see, everything seems to be OK since the LEDs are lighting up.

I'm measuring the following Values:

V+/G/V-: -9,71V/+10,33V (Are the 0,6V difference okay?!)

DC-Offset: 1,3mV/2,0mV

Across the 2x68Rs: 1,65V/1,72V



I have some questions and Salas short-answered them already. He also wrote that it would better to ask here, so everyone can benefit from his answers.


Question: Grounding... Are just the Inputs/Outputs grounded or should the board also be grounded (there where you can measure the 10V+-)?
Answer:
You may ground to chassis from transfo connector's center, many leave it floating, if they get hum they ground.


Question: You once have written in an older (?!) DCB1-guide "See that you have 2V+/-0.3V across R1 combinations." In the mesmerize-schematic, R1 is one of the 220R at the Output. I'm a little bit confused here and I am not sure which Rs you really mean.
Answer:
Rs=Setting resistor (main current source). In Mezmerize they are those two flanking each main filter capacitor along the board's edge.


Question: Is there anything else to do before checking the Output-Offset? E.g. short-circuiting Inputs or sth. like that.
Answer:
You should see to get under 5mV DC offset with both shorted or open input. So to cover all situations.


Further Questions:

You mean the parallel 68Rs where 2V+-0,3 DC should be measured? Yeah, I had a guess Vdrop should be measured there.

In the BOM, there are 2 decoupling film caps. I found the 100nF footprint, but where's the footprint for the 150nF? It says "Near BC517". Maybe this a relict from an older BOM-version and is obsolete?

Is there anywhere a version of the mesmerize-schematics where the descriptions are clearly readable and not overlapping?

Greets

n00b


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Old 3rd May 2012, 03:48 PM   #523
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Here are some pictures of my nice sounding Mezmerize.
Unfortunately I forgot to mill some slots in the top plate for cooling.
But in my opinion it`s not realy warm inside (after 6 hours hearing :-).
The space inside where the aluminum bars are is for the remote control pcb.

Andreas
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Old 3rd May 2012, 04:01 PM   #524
Salas is online now Salas  Greece
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Aesthetically pleasing.
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Old 3rd May 2012, 04:10 PM   #525
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Nicely finished but your heatsinks are doing virtually nothing the way you have them orientated.

You could cut 3/4 of the lenth of them away and they would be doing the same for your heat disipation.
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Old 3rd May 2012, 04:24 PM   #526
Salas is online now Salas  Greece
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Quote:
Originally Posted by n00b View Post


I'm measuring the following Values:

V+/G/V-: -9,71V/+10,33V (Are the 0,6V difference okay?!)

DC-Offset: 1,3mV/2,0mV

Across the 2x68Rs: 1,65V/1,72V

...

Further Questions:

You mean the parallel 68Rs where 2V+-0,3 DC should be measured? Yeah, I had a guess Vdrop should be measured there.

In the BOM, there are 2 decoupling film caps. I found the 100nF footprint, but where's the footprint for the 150nF? It says "Near BC517". Maybe this a relict from an older BOM-version and is obsolete?

Is there anywhere a version of the mesmerize-schematics where the descriptions are clearly readable and not overlapping?

Greets

n00b


Your measurements are OK. Some difference in +/- supply values is normal in Mezmerize (not in Hypnotize) since its designed to be quasi symmetric for THD shaping that helps it subjectively at low PSU currents.

Further: Yes, on those 68R//68R. Those 150n were help in case of mechanical resonance in the output relay for those who could not bother or did not have access to BC517 Darlington and used BC550C etc. Strapped between C,B under PCB could delete oscillations with relay's inductance.

Should be back in the depths of the years long threads.
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Old 3rd May 2012, 04:28 PM   #527
Salas is online now Salas  Greece
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Quote:
Originally Posted by andreas w. View Post
But in my opinion it`s not realy warm inside (after 6 hours hearing :-).

Andreas
Since its not hot rodded and not warm it should be safe. Spot check the temp on the Mosfets with a thermocouple or thermometer gun at a point if feasible to have a clear evaluation. If nothing is over 60C locally its a pass.
What is the rest of the system and what was line stage before?
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Old 3rd May 2012, 04:49 PM   #528
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The rest of the system are Pearl Phono and Symasym amps.
To be on the safe side I will measure the temperature of the Mosfets.
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Old 3rd May 2012, 05:03 PM   #529
Salas is online now Salas  Greece
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Quite a ''Scandinavic'' wooden system look. Loudspeakers are?
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Old 3rd May 2012, 05:07 PM   #530
AndrewT is offline AndrewT  Scotland
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Andreas' creations deserve a permanent place in the PICs Thread.

I particularly like the "family" look of post528. Nice !
Except for the bluleds
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regards Andrew T.
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