Author Topic: Press the IN switch and check that the front panel LED and meter light up . help

February 09, 2021, 04:04:01 PM
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Jason

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Hi, 

In switch lights up, but meter dosent and shoots up past 20db? 

all voltage is correct in the first steps.


 

February 09, 2021, 04:11:35 PM
Reply #1

Jason

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February 09, 2021, 04:35:48 PM
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JPK

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Look for a short-circuit between Vu- and any other pin on CN2. Same thing for Vu+.
JPK

February 09, 2021, 05:09:54 PM
Reply #3

Jason

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Sorry could you please explain in detail how to do that, I'm a novice and completely out of my depth. 

February 09, 2021, 05:34:56 PM
Reply #4

JPK

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With your DMM set to ohms (or better set to ring mode if it can do) place one probe on the Vu- pin then with the other probe check all the other pins for a very low resistance (or a ring).
Repeat for Vu+.
JPK

February 09, 2021, 05:54:05 PM
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Jason

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February 09, 2021, 06:27:32 PM
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JPK

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JPK

February 10, 2021, 10:04:41 AM
Reply #7

Jason

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Apologies, 

Didn't have any power running through it. I've done another test and there is a sort circuit when the probe is on V+ and touching +12v All the other TP are fine.

February 10, 2021, 10:18:02 AM
Reply #8

JPK

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The short circuit test must be done without power but with the main and front PCB's connected together and the meter connected to the front PCB.
JPK

February 10, 2021, 11:37:46 AM
Reply #9

Jason

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No there is no short circuits and everything is connected as you said. when I probe CN4, the meter moves on everything apart from the red and on D3, k lights up and long shoots to 20DB, if this info is any good to you.
« Last Edit: February 10, 2021, 12:24:03 PM by Jason »

February 10, 2021, 04:01:36 PM
Reply #10

JPK

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Quote
also the Led lights up really bright ?
You have too much current in the LED. The current is limited by R104, RLY1, Meter LED.
- Remove the IC's until this is sorted out.
- Check the meter (unplugged): 600 ohms between the large terminals, infinite resistance between any 2 other terminals.
- Check the relay coil (in circuit), 2800 ohms across D19 (check D19 direction).
- Check R104 value (in circuit).
JPK

February 12, 2021, 09:21:30 AM
Reply #11

Jason

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- Remove the IC's until this is sorted out. Done
- Check the meter (unplugged): 600 ohms between the large terminals, infinite resistance between any 2 other terminals. 562 ohms large infinite resistance between any 2 other terminals.  Short Circuit Small terminals when connected to PCB C 
- Check the relay coil (in circuit), 2800 ohms across D19 (check D19 direction). 2.73
- Check R104 value (in circuit). .217
« Last Edit: February 12, 2021, 09:29:45 AM by Jason »

February 12, 2021, 11:26:45 AM
Reply #12

JPK

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It seems the short is on PCB C.
Check between the 2 center pins of CN4 when the meter and PCB A are disconnected.
JPK

February 17, 2021, 07:31:27 AM
Reply #13

Jason

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It seems the short is on PCB C.
Check between the 2 center pins of CN4 when the meter and PCB A are disconnected.
Yes, there is a short circuit ?

February 17, 2021, 11:10:11 AM
Reply #14

JPK

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Do you also have the short when the IN switch is off?
JPK

March 08, 2021, 04:45:12 PM
Reply #15

Jason

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March 10, 2021, 11:47:10 AM
Reply #16

JPK

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You should be able to see the short on the CN4 pins. The track from pin 2 is very short, it only goes to the LED D3. 
JPK

March 22, 2021, 12:58:22 PM
Reply #17

Jason

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I had 2 lifted pads on D3 problem is now solved 

Thank you 

March 22, 2021, 05:16:31 PM
Reply #18

JPK

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