Author Topic: Output transformer geometry - is this normal?

October 31, 2022, 08:05:33 PM
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AcdNrg

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Aesthetics aside, my concern it that the metal may connect to a neighbor module if that one is also "boxed". But as I didn´t finish final assemply, I can´t tell yet.
« Last Edit: October 31, 2022, 08:12:02 PM by AcdNrg »

October 31, 2022, 08:09:56 PM
Reply #1

AcdNrg

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November 02, 2022, 06:50:06 PM
Reply #2

JPK

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Have you added the four 4mm spacers under the transformer?
If so, you could try to add some washers on the side that sticks out from the chassis.
JPK

November 05, 2022, 12:42:41 PM
Reply #3

AcdNrg

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Yes, spacers are in place. Added 4 washers for aesthetics, double checking that there is enough room for PCB2. That is resolved now.

Still can´t finish the calibration though. Everything is fine except the Threshold Stage, where I get much higher voltages than expected and no effect of TR3 at +9dB:




4. PCB1 Voltage
V+ = 15.746
V- = -15.808
PASSED

LED check
PASSED

5. BIAS
TP2-TP3 = 3.003V
PASSED

6. Input Signal
Output at Chassis = 1.0004 VAC
PASSED

7. 0dB Gain
Output : 1.0004 / 1.0006 VAC
Makeup: up to 13.165 VAC
PASSED

9. 3V Adjust
3.001V
PASSED

CV Adjust
Bypassed: 2.451 VAC
Active: 0.9782 VAC
PASSED

10. Meter Adjust
8dB
PASSED

Threshold Adjust
JMP1 1-2 OK

1kHz at -6dB
Threshold -6dB SET
Bypassed: 6.151 VAC OK
Active:
fccw 6.143 FAIL
fcw 5.022 FAIL

1kHz at -18dB
Threshold -18dB SET
Bypassed: 1.5502 VAC OK
Active:
fccw 1.5472 FAIL
fcw 1.1994 FAIL

1kHz at +9dB
Threshold +9dB
Bypassed: 6.152 VAC OK
Active:
fccw: 6.139 VAC FAIL
fcw: 6.14 VAC FAIL


Measured onboard:
r35 4.6947 kOhm OK
r43 2.19 kOhm OK


What am I doing wrong? From a quick audio test, the compressor works and is doing something, but the threshold calibration is totally bonkers.





« Last Edit: November 07, 2022, 07:19:47 PM by AcdNrg »

November 07, 2022, 04:39:07 PM
Reply #4

JPK

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THRESHOLD adjust :
input 1kHz 6.15 VAC
Threshold -6dB
Bypassed: 6.151 VAC OK
Active:

In the THRESHOLD adjust conditions, with 6.15VAC at the input :

With JMP1 removed:
AC volts on TP4 : 2.8V (varying with trimmer TR3)
AC volts on TP5 : 2.8V (varying with trimmer TR3)

With JMP1 back in position 1-2:
DC volts on JMP1-pin1 : 4.7 VDC


« Last Edit: November 08, 2022, 03:47:54 PM by JPK »
JPK

November 07, 2022, 07:52:59 PM
Reply #5

AcdNrg

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I get the 2.8 VAC on pin4 and 5 (2.799 + 2.798 ) against 0V

I don´t get any VDC on pin1 of JMP1 (marked by the dot), no matter if jumper is installed or not.

That said:
JMP1-pin1 to 0V = 0.0003 VDC
JMP1-pin2 to 0V = 0.0000 VDC
JMP1-pin3 to 0V = 3.001 VDC

For what it´s worth, on pin1 I get
12.336 VDC at Threshold set to -9dB
14.280 VDC at -12 dB
14.587 VDC at -15 dB
14.716 VDC at -18 dB

To be honest, I don´t know what I´m measuring here :), so hopefully those numbers make some sense to you.

The compressor still works (from meter movements and musical material)


November 08, 2022, 03:51:56 PM
Reply #6

JPK

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I don´t get any VDC on pin1 of JMP1
12.336 VDC at Threshold set to -9dB
These 2 lines seem contradictory.
Do you mean it is only at Threshold -6 that you get no DC on pin1?
JPK

November 08, 2022, 04:33:53 PM
Reply #7

AcdNrg

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It seems I get 0 VDC on every setting higher than -9dB:

jumper JMP1 pin1-pin2 installed / not installed

-21 dB: 3.546 / 14.783
-18 db: 3.132 /14.717
-15dB: 2.686 / 14.587
-12 dB: 2.277 / 14.279
-9 dB: 1.811 / 12.321
-6 dB: 0.0024 (slowly falling to 0.000) / 0.0006
-3 dB: 0.0003 / 0.0003
0 dB: 0.0003 / 0.0003
etc. no change up to 12 dB

I made sure the jumper bridge has contact, even if the setup looks a little flimsy :)




November 08, 2022, 09:02:18 PM
Reply #8

AcdNrg

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OK, it´s official now. I´m an idiot.

Since switching the threshold looked fishy, I decided to

- reflow all switch solder joints on the treshold switch
- reflow all connector joints on switchboard on PCB2

No change. Soooo, we´re in for the long run: Check all parts.

Low and behold, take a close look at D4



And that´s why DIODE Bridge Compressors will be known as Diodevil Bridge Compressors in my book from now on.

Let this be a warning to others to not build this kit over a long night with too many distractions...

Apologies for wasting your time and braincycles! I did a full calibration, all values within expected ranges, now I´m a happy man.

Best regards and thank you for your patience! 

November 10, 2022, 12:52:56 PM
Reply #9

JPK

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