Mezmerize DCB1 Building Thread

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? :D 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 Maybe this a relict from an older BOM-version and is obsolete?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 :cool:

n00b


 

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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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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? :D 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 :cool:

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.:cool:
 
diyAudio Chief Moderator
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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?
 
The speakers are Scan A4 Monitor SE.

Andreas' creations deserve a permanent place in the PICs Thread.

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

Thank you, Andrew.
If you have a look at "Pictures of your diy Pass amplifier" you will see Aleph J, Aleph P1.7 and ONO in the "family" look and blue led as well ;)
 

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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.


Look back at post #501 to see how to mount the heatsinks more efficiently.

If you are only running at 100mA or so then it probably wont hurt as the MOS-FETs will be running fairly cool anyway.

With the 10R resistors in the photo the MOS-FETs don't really need any heatsink at all. I've just been experimenting with 3R0 and 4R7. At 3R0 even the 2E heatsinks that I used are barely sufficient and the MOS-FETs are running too hot for my liking - allbeit only about 55 Degrees C. I haven't tried the 4R7s yet as I'm enjoyiong it too much.
 
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Stock for suitable relays are becoming more difficult to find.

Has consideration been given to this for the future?

Is EA2-12-DC12V equivalent to EA2-12NJ-DC12V?

I think the "NJ" designator is for "trimmed leads" and would have no affect upon function.

NEC EA2 series? Those are compatible and can even arguably have the best contact quality.
 
Checked! Leds are fine and well positioned. On the working rail i have around 2v across 5 leds group and on the non working rail around 10v.

Think i've found the problem: some reading error conducted me to install IRFP9240 instead of IRFP240.
 
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