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


bricol67

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Hello,

 

Short presentation: I am French and I encountered a problem similar to yours, with a Jamo D600SUB subwoofer.
The power strongly resembles the one photographed by Journey.


Thanks to the patience and the many hours spent by "Journey" for the reading of the diagram that he shared, I managed to repair my power, which works perfectly again.

Thank you, Journey.


For information, on my subwoofer, the 1ohm resistor R6 was out of order, the +/- 15v was missing.

I have attached some photos of the electronic cards.

 

1420760203_IMG202110101410371024x768.thumb.jpg.bd7bf92c931fd5ffebe00f40193a5e0b.jpg

 

1317731401_IMG202110101409511024x768.thumb.jpg.5cfbe3506a3d7940ca83d8f7c76d6a0c.jpg

 

1957118767_IMG202110101409591024x768.thumb.jpg.6baf830c746385ceb1f2e88a6d36f1df.jpg

 

1853660699_IMG202110100949481024x768.thumb.jpg.730f601b1c7133dc641b69ba345192a4.jpg

 

1782066798_IMG202110100951111024x768.thumb.jpg.fec576ba5cf1e588bc318926b40e2d6a.jpg

 

185874782_IMG202110100951441024x768.thumb.jpg.4f3827b7d53638b721400e1a4520bf0f.jpg

 

463667089_IMG202109191755221024x768.thumb.jpg.f6e882054474adbed68ae73ef8786196.jpg

 

97003769_IMG202110100946251024x768.thumb.jpg.7b94666fbf09882fe40d22960a526080.jpg

 

1715913534_IMG202110101410041024x768.thumb.jpg.e6ed28fd4c23d4fbda36d3cf979c3747.jpg

 

586669039_IMG202110101410161024x768.thumb.jpg.b99ef3f12f4677a7183a6df59e7b392e.jpg

 

The subwoofer is not mine, but if you want some information, or if I want to take measurements, I can do it for you while I still have the subwoofer.

 

Good research is hope you can fix it.

 

Sorry for my English, I am using google translate!

Bricol67

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Hello,
I also have a broken Jamo D600 at the moment I only found the two FQP17N40s shorted and visually I can't see anything else yet. The problem was that when the amplifier was on, the speaker would start to buzz when there was no input signal.
Could you measure on yours that works the value of the resistance of the diode marked D8 in front of the MBR20200C. What were the symptoms of your D600 ?

Thanks in advance.

20210912_15133.jpg

Edited by Yroger
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  • 2 weeks later...
On 10/11/2021 at 6:33 PM, Yroger said:

Hello,
I also have a broken Jamo D600 at the moment I only found the two FQP17N40s shorted and visually I can't see anything else yet. The problem was that when the amplifier was on, the speaker would start to buzz when there was no input signal.
Could you measure on yours that works the value of the resistance of the diode marked D8 in front of the MBR20200C. What were the symptoms of your D600 ?

Thanks in advance.

20210912_15133.jpg


Buzz almost always means BAD CAPS. Replace the 6 smaller Carli caps and all the electrolytics. Blown FETS mean gate resistors need to be checked and also the control PCB.

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Thanks for the info, but I had already tested all the capacitors and their ESRs were okay, the 10 ohm resistors are good too. A visual check of the cards does not reveal any traces of burns or of a component that has heated; difficult ... Actually the speaker starts to move very high and therefore audible when switching on, there is also the control panel which does not switch on. After this test phase I rechecked the MOSFETs and they are still good ?? For information, I was able to briefly measure the supply voltage on capacitors C49,
C50 and C20 there are about 150Vdc. I also measured on the CD + and CD- pins 7.2V is this sufficient ?
Thanks for your help.

Edited by Yroger
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Hello Yroger,


I don't quite understand your problem. You indicated that you had a buzz when there was no input signal. Why are you looking for a power failure?
FYI, on this subwoofer, there is a motion sensor stuck on the speaker. It is often he who causes the buzzing (just unplug it to validate the diagnosis).

 

Answer to your questions:
Resistance of diode D8: without disassembly = 6.2k in both directions (to check a diode it is better to unsolder it to be sure)
Voltage at CD + / CD- terminal: seems correct in standby mode.


To begin with, you must check for the presence of +/- 15v on connector J2 terminal 1 & 3. If not OK, you must see if power supply U1 & U2 is OK

 

Sorry for my English, I am using google translate!

 

Good research

Bricol67

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Thank you Bricol67,
The sensor connected or not it does not change anything and I have no display on the control panel!
- For D8 it's TH3 in fact see my photo where I had surrounded the component. I have about 120K in both directions (not soldered)
- Tomorrow I will check the 15V on pins 1 & 3
Thank you for allowing me to move forward on this subwoofer.
I also use google translate ...

 

Edited by Yroger
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To begin with, you must check for the presence of +/- 15v on connector J2 terminal 1 & 3. If not OK, you must see if power supply U1 & U2 is OK

 

Yes I have + and - 15V in unloaded power supply output.
There is another connector or there are 4 wires. It is not present on the feeds presented on this discussion thread. Surely specific to a function defined by the specifications of the company Jamo. Without a diagram, it's not easy. Where should I orient myself now ?
Thank you.

 

I measured a voltage of 10Vdc (power supply not loaded) on the 4-wire connector (red and black wire) and once the cable is connected to the other card, a voltage of 8.5Vdc.
the other two give nothing convincing.

 

Jamo_D600_Subc.jpg

Edited by Yroger
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OK for the +/- 15V.

The 4-wire connector is indeed specific to Jamo. This is the standby command. With the cable plugged into both boards, you should measure around 9V between red and black and between red and orange. Between red and green there is about 1.5Vdc.

 

Note: pay attention to the "Off / AUTO / On" switch which must be on "On" otherwise the power supply will not start.

 

You can check the following voltages:

 

1106296860_Lestensions.thumb.jpg.07f871a7dd9c619f5d30c2d943266b77.jpg

 

 

Good research.

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On 11/4/2021 at 6:41 PM, Yroger said:

No actually
And on your side the hp and the mfb circuit were they connected too?

 

Hello Bricol67 so in the same configuration as you the measured voltages are the same see my previous post photo. Connected or not it does not change anything !

 

Maybe the problem comes from the control panel itself but as it is stuck in the box I would prefer to be sure that it is him to blame before taking it off (not easy). I also made some measurements on the connector of the control panel in the box:

The other pads are like diode readings!

 

Control pannel.a.jpg

Edited by Yroger
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Bonjour Yroger,

 

Je ne pense pas que votre problème soit au niveau du panneau. Si vous n'avez pas la bonne tension sur le connecteur, votre alimentation ne fonctionne pas.

 

Je vous envoie les valeurs de tension que vous devriez trouver sur le connecteur J2 de la carte d'alimentation.
Si le connecteur de veille est branché, il n'y a pas de tension sur le connecteur J2.

 

969937512_Powervoltagevalue.thumb.jpg.2fe0e3993a45fb5c4a117232f35b3547.jpg

 

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