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Jamo D600/RT - 12D Amplifier Power Supply Circuit Repair


bricol67

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j3 not connected (switch position on):

-2.3v (orange and green) and 10,7v (red and orange)

j3 connected (switch position on):

7,1v (orange and green) and  8,7v (red and orange)

I also listen to a slight crackle when I turn on the power and I wonder if this is not what echoes in the speaker !

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Hello Roger,

 

It was not the pain of all desoldering because your power supply is working, except for standby. Your problem is on the small control card.
Attached is the diagram of the primary power supply, identified by Journey.
I partly added Jamo standby.

 

80349624_Primarishutdown.thumb.jpg.d543d3af0bfce054d1a441713959d973.jpg
It must be checked whether the voltage between the negative of the primary and terminal 1 (DB2 card) changes when you connect J3 or not.


Be careful when you take the measurements in the primary power supply part, there are very high voltages !!

 

If the voltage changes, the problem is on the DB2 control board. Otherwise it is the optocoupler on the standby card.


Personally I would lean towards a problem with the IR2153 integrated circuit, since your power transistor was short-circuited.

 

Your amplifier does not start because it goes into protection mode, because of the voltages present on the J2 connector.

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I'm sorry, I can't take the measurements anymore. The owner recovered the subwoofer.
I can always help you repair your subwoofer.

 

I think it is normal to have the same value in both directions on the diodes because they are in parallel with resistors.
To be sure, you have to desolder the diodes or the resistor in series.
It's the same for resistors, you have a parallel series connection.

 

Have you checked the voltage on terminal 1?
Did you replace the IR2153?

 

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I'm sorry, I can't take the measurements anymore. The owner recovered the subwoofer.
I can always help you repair your subwoofer.

 

Do not be sorry because you have allowed me to make good progress in the search for the defective elements of this amplifier.

 

To be sure, you have to desolder the diodes or the resistor in series.
It's the same for resistors, you have a parallel series connection.

 

Yes I know the principle but good rather than desoldering them if you had still in your possession the power supply it would have been easier; shame.

 

Have you checked the voltage on terminal 1 ?
Did you replace the IR2153 ?

 

Not for the moment I am waiting to receive 3 capacitors of 1000µF 200v to replace C49, C50 and C20 as long as to replace them I take this opportunity to increase their capacity a little (there is room). For the Jamo version of this power supply we had two 680µF and one 470µF

Thank you very much for your work !!

Edited by Yroger
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Quick question: Is the 0 ohm resistor (R48) present on our power supply ? I have a doubt !I have a voltage of -313V J3 connected and 292V J3 not connected. I replaced the IR2153 and it's the same.

I took the time to do the little assembly to test the IR2153 posted by Journey on page 6. They are ok !!

Edited by Yroger
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Have you already received the components? Well say it's fast!

 

For the R48, I have trouble seeing in the photos I took, but I don't have the impression that it is there. But I noticed that there are small differences between the Klipsch and Jamo power supply. The diagram I published is that of Journey and it is a Klipsch power supply. There are perhaps some reading errors, because it is very complicated on double sided.

 

What negative did you take to have this tension? In theory, if you measure between negative and pin 1 you are at the terminals of the optocoupler.

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For the R48, I have trouble seeing in the photos I took, but I don't have the impression that it is there. But I noticed that there are small differences between the Klipsch and Jamo power supply

 

I also think there was none.

 

For the test carried out previously it must be kept in mind that all the capacitors and various components and control boards have been resoldered !!
Measurement taken between pin 1 DB2 card and capacitor C50.
Only the control panel is not reconnected !

 

Alim test1.jpg

Edited by Yroger
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It seems to me there is a problem with the polarity of the diode bridge and the C49 C50 capacitors on the diagrams posted in the discussion thread !! In our case it is the positive of the diode bridge as well as the positive terminal C50 which are connected to C46 ...

Edited by Yroger
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Good evening Roger,


I just looked at the photos I took and the klipsch diagram. I hadn't paid attention, in fact there is no 110 / 220V selection on the diagram that's why there is the R48.
Indeed there is an error in the direction of the diode bridge and the capacitors on the diagram and I now understand why you are measuring -313V.


In fact, you have to measure between the negative of C49 and terminal 1.
With the J3 connector plugged in, you should find about 0.5v or 0.7v.
With connector J3 unplugged this voltage should increase to about 10 to 15 volts.


In the diagram of the control card there is also an oversight, I had trouble understanding how it can go to sleep! With another diagram found on this thread I understood. A small connection is missing and that changes everything!
I corrected the errors and added some information for better understanding.

422725629_Primarishutdown.thumb.jpg.b8d1bb9bf3d78142a7b22eaad3a15774.jpg
Good luck, you will be able to fix this damn power supply.

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Hello Bricol67,

 

In fact, you have to measure between the negative of C49 and terminal 1.
With the J3 connector plugged in, you should find about 0.5v or 0.7v.

It's good I measure - 0.5v

 

With connector J3 unplugged this voltage should increase to about 10 to 15 volts.

It's good I measure 16v

I have more and more the impression that the mains supply is not the cause of the failure. Little additional information: (fully connected amplifier, ready-to-use subwoofer). When the power is turned on and there is no signal applied to the input, the loudspeaker goes boom boom and the control panel does not light up ! If I disconnect J3 and repeat the operation the speaker generates hiss instead of the boom boom and the control panel still does not react !

 

Roger.

 

 

 

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Hello Yroger,

We might have misunderstood each other, but there are a couple of posts back you said:

 So I think it's moving forward. So we have a problem see diagram. the voltages are identical whether the J3 cable is connected or not !

 

 

If this is indeed the case, that the voltages on J2 do not go to 0, with a voltage of 8V on the standby pin of J3, your power supply is not working correctly.

 

Can you confirm that it is working fine, if so the power supply is working.

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I admit being a little lost with all these pins and connectors connected or not ....

 

If this is indeed the case, that the voltages on J2 do not go to 0, with a voltage of 8V on the standby pin of J3, your power supply is not working correctly.

 

in fact the standby pin on J3 and 1 ?? On your modified diet diagram posted on 10.11 at 07:44 PM, you noted: pin 4 J3 stanby ???

 

 

1864394259_Primarishutdown.jpg.ab03b6ab25d4bd40c5a30c4690f26c26.jpg

Edited by Yroger
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in fact the standby pin on J3 and 1 ?? On your modified diet diagram posted on 10.11 at 07:44 PM, you noted: pin 4 J3 stanby ???

Well no, it's not pin 1 it's pin 4, as shown in the photo and the diagram.

 

Review what you scored on Saturday at 06:52 PM.
It is indeed the green pine which changes voltage -2.3v => 7.1v

j3 not connected (switch position on):
-2.3v (orange and green) and 10.7v (red and orange)

j3 connected (switch position on):
7,1v (orange and green) and 8,7v (red and orange)

 

If you want to test the power supply alone, just put a changeover switch as in the attached photo (J2 and J3 not connected to the other boards).

The voltages at the outputs on J2 must react as indicated in the post of Saturday at 02:11 PM

 

1664484333_J3powersupply.jpg.6b64b513f2ffb20d7222aba05975f68b.jpg

 

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