Author Topic: High signal Output first channel

July 27, 2021, 09:38:11 pm
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Peevb

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Hi,

I'm looking for some guidance on my issue.

Channel A did not work on first start.
I swapped IC U6 (from U16 chB) because I did not place it in correctly. I know, checked it 3 times but it happend.
Once I use the chB (u16 IC) I get signal once the in button is engaged but it is very loud and not trim-able.

chB works just fine with the U6 IC that was reversed in orientation and I can calibrate.

So I did some reflowing and the common mistake section but the problem persists.
So I swapped all the IC's that are common to chB but the problem persisted.

I need guidance on howe to further localise the problem.

Thanks in Advance
« Last Edit: July 27, 2021, 09:41:48 pm by Peevb »

July 29, 2021, 08:07:26 am
Reply #1

JPK

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Please report the voltages detailed here: https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3
JPK

July 29, 2021, 08:33:53 pm
Reply #2

Peevb

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Mix = 100%
Ratio = 10

Attack = 0.1

Release =1.2

IN button pressed

HF lift, 100Hz, 50Hz buttons released
Negative meter probe on 0V


All good other then,
TP2 = 15.4V

did I fry a vca with the reversed IC U6?
« Last Edit: August 14, 2021, 04:55:28 pm by Peevb »

August 01, 2021, 08:36:42 am
Reply #3

JPK

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Check that there is no component lead touching the chassis plate.
Check you have the correct resistors in R106, R46...R53.
Can you report the DC volts on the 8 pins of U6?

Can you check with an ohmmeter in ring mode that the solder joints of the THAT2181A are all good, in case we missed some.
The connections are marked in red in the attached picture. Verify the continuity between the IC pins and the corresponding pads.
You will need sharp meter probes to do this.

JPK

August 02, 2021, 07:35:46 pm
Reply #4

Peevb

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Check that there is no component lead touching the chassis plate. -- No component is touching the chassis
Check you have the correct resistors in R106, R46...R53.      -- R106 (I have a REV1.3 R106 does not exist checked components list) R46=20K R53=5.1k (R43=1.6k)
Can you report the DC volts on the 8 pins of U6 -- 
relative to ground
1  0Vdc
2  0Vdc
3.  0Vdc
4  -15.99Vdc
5.  0Vdc
6.  0.75Vdc
7.  -15.4Vdc
8  16Vdc
Can you check with an ohmmeter in ring mode that the solder joints of the THAT2181A are all good, in case we missed some.
The connections are marked in red in the attached picture. Verify the continuity between the IC pins and the corresponding pads.
You will need sharp meter probes to do this.


Continuity is correct between IC u6 and VCA U2 and U5 according to the schematic sch REV1.2 CP4500 last modified 30/01/19
I don't understand the picture you send.

Once again thank you for the help.


« Last Edit: August 14, 2021, 04:56:19 pm by Peevb »

August 03, 2021, 10:01:12 am
Reply #5

JPK

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Quote
I don't understand the picture you send.
Sorry, this is for revision 1.4.

You have DC on U6 pin7 (=TP2). It should be 0.
Remove U2 to U5.
The DC on TP2 should be back to 0.
Insert sequentially U2 to U5, checking each time the DC on TP2.
Is there one IC that causes the DC rise ?
JPK

August 04, 2021, 07:13:43 pm
Reply #6

Peevb

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Tested continuity between U6-pin-7 and TP2 - OK

Thr -15
ratio: 10
Attack: 0.1
Release: 1.2
Makeup: 0
Mix: 100%
Comp: IN

Pulled VCA, U2 U3 U4 and U5. All measurements = TP0V - TP2


No VCA's  = 0Vdc
only U5 = 15.4Vdc
only U2 = 15.4Vdc
only U3 = 15.4Vdc
only U4 = 15.4Vdc

I tried multiple That2180A same result.
Pulling U6 lowers to 1.18Vdc on TP7

Voltages U5, U2 U3 U4 Pinheader
Pin7 = 16Vdc
Pin 6 = 0Vdc
Pin 5 = -15.9Vdc




August 05, 2021, 05:03:08 pm
Reply #7

JPK

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With U2 to U5 and U6 removed what are the DC voltages on the 8 pins of U5?
JPK

August 14, 2021, 04:54:26 pm
Reply #8

Peevb

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With U2 to U5 and U6 removed what are the DC voltages on the 8 pins of U5?
Pin - Vdc
1 = 0.22
2 = 0
3 = 0
4 = 0
5 = -15.9
6 = 0
7 = 15.9
8 = 0.09

August 15, 2021, 08:38:03 am
Reply #9

JPK

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All OK except pin 1 which should be at 0V (actually floating).
Do you see any DC voltage on TP1?
JPK

August 15, 2021, 11:46:22 am
Reply #10

Peevb

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All OK except pin 1 which should be at 0V (actually floating).
Do you see any DC voltage on TP1?
U2/U5 and U6 removed


TP2 Relative to TP-0V = -0.06Vdc

August 16, 2021, 02:54:17 pm
Reply #11

Peevb

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All OK except pin 1 which should be at 0V (actually floating).
Do you see any DC voltage on TP1?
Oh Sh*t I did TP2 in the previous post but you asked TP1

U2/U5 and U6 removed

TP1 Relative to TP-0V = 0Vdc

August 16, 2021, 05:54:10 pm
Reply #12

JPK

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I am short of ideas, maybe it is time to send us the unit for a closer check?
JPK

August 16, 2021, 06:06:15 pm
Reply #13

Peevb

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I am short of ideas, maybe it is time to send us the unit for a closer check?
Are you ok if I run it by a professional local engineer first? I'll log here if we need further assistance or made a conclusion. Thank you for your support so far. I'll soon get some more modules from the store. Take Care, Pascal. 

August 17, 2021, 08:39:04 am
Reply #14

JPK

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Of course, no problem.
JPK

Today at 08:07:50 am
Reply #15

laurenny60

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