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Mezmerize DCB1 Building Thread
Mezmerize DCB1 Building Thread
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Old 6th January 2019, 07:42 PM   #2081
gwrskien is offline gwrskien  Norway
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Mezmerize DCB1 Building Thread
@ Meper You can get an "potentiometers extension kit", or build one your self with parts from the bay..

Drill hole in front panel, pillow block with set screws, to hold extension rod in place, bolted to the back of the front panel, rod with coupling one end,potmeter mounted on angle braket, volume knob other end
Use these search words at the bay, and you should get the idea..
Pillow Block Bearing Flange
Stepper Motor Coupler Connector
bearing block
Smooth Rod Steel Linear Rail Shaft
cnc copling
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Old 7th January 2019, 05:26 AM   #2082
MEPER is offline MEPER  Denmark
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Ok.....thank you very much. I will try that…...
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Old 7th January 2019, 05:14 PM   #2083
edd9000 is offline edd9000  United Kingdom
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Quote:
Originally Posted by MEPER View Post
Is it a "press fitting" of ball bearing into the front panel and 6mm shaft into the ball bearing?
Press fit on shaft and a slide fit into the housing.
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Old 7th January 2019, 08:00 PM   #2084
MEPER is offline MEPER  Denmark
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Thank you!
I took the easy solution and ordered a 3 mm front panel so I can mount the attenuator directly on the panel. I can see that depending on the distance to the PCB there can be a technical advantage in having a long shaft to the attenuator so wires will be as short as possible.
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Old 27th January 2019, 03:13 AM   #2085
OhSoJoe is offline OhSoJoe  United States
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Hi All,

I just powered on a moderate hotrod version, 2X20 Ohm resistors per side, and my voltage across these resistors is 10V. Way too high. Input voltage is 17V AC. Channel voltage is 10.58 and 9.99 and the offset is 0.7 and 0.1 mV. Everything should be matched, but I could have gotten something mixed up after testing. I can already see some slight discoloration in the input resistors, so before I power it back on to take additional measurements I'd appreciate any input.

Thanks!
Joe
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Old 27th January 2019, 09:13 AM   #2086
Salas is offline Salas  Greece
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Mezmerize DCB1 Building Thread
The voltage across those resistors should be about 1.75V when things are normal. Check their nearby IRFP types if been accidentally swapped around for PMOS/NMOS.
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Old 27th January 2019, 12:54 PM   #2087
OhSoJoe is offline OhSoJoe  United States
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Yup... That's what I did. Thanks!

Now reading 1.65V and 1.77V. Channel voltage is 9.85V and 10.45V and the offset at the output is 0.5mV and -0.9mV. Is it worth switching around LEDs to even out the channel voltage given the low offset?

Cheers,
Joe
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Old 27th January 2019, 01:52 PM   #2088
Salas is offline Salas  Greece
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Mezmerize DCB1 Building Thread
No, the rails voltage won't change much. Its rigged to mismatch their DC so*. You could mutually swap the two signal JFETS in the 0.5mV channel to have a minus reading as in the other channel. If you want to be perfectionist that is. A minus means their two IDSS are in the right order i.e. the top FET isn't marginally saturated by the bottom one (top & bottom when schematically speaking). Performance wise it does not have an impact when so well matched already.

*If you want to even that out as its already a feature in the 10 Years After Edition PCB see about doing the "leg trick" in your earlier edition: Mezmerize B1 Buffer Preamp
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Old 5th February 2019, 05:44 PM   #2089
Russellc is offline Russellc  United States
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Mezmerize DCB1 Building Thread
Quote:
Originally Posted by MEPER View Post
Is this a Khozmo kit or your own invention with ball bearing in the front panel?
I need to find a solution for the 10mm front panel I have for the BA-3 pre. The easy solution would be to just get a 3mm panel and mount the attenuator as usual.
A little late, but I found that the extender kit from PartsConexcion worked great on the 10 mm panel.

Russellc
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Old 5th February 2019, 05:54 PM   #2090
MEPER is offline MEPER  Denmark
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Thank you!
I took the easy approach and ordered a 3mm front panel!
It plays very well. Now I just need to adjust the distortion…….I will "play" with that in the near future. Now P3 is just set to center position.
I have no hum and that is good. Noise is also low. So I guess I did something right with how the ground wires are connected etc......even with relative long twisted signal wires it works.
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