Good day,
First of all I'm new here, so I'd like to say hello to the DIY community 🙂.
I'm a French musician and like DIY stuff like guitars, effects (analogical), and controlers (arduino / midi /display). But today I have an issue with my non DIY home studio ADAM A7X monitors that I don't know how to fix. So I was thinking that maybe I could find help in this forum.
Indeed, when I switched on the monitors, one of them just “Pok”, and did work no more. I found the input fuse blown and the rear switch set at 115V instead of 230V (kids did that bad joke...).
After changing the fuse with a new one, setting back to 230V, only the tweeter works now (these monitors have separate amp for tweeter and sub).
I investigated further until swapping the power card (card connected to the transformer), with the power card of the other A7X monitor not damaged. Then it worked fine.
Therefore, changing this power card is a solution, but it’s quite expensive (~Card costs about 250€) , so I would like to repair the card myself. To do so I would have to find out which component has been damaged. If any one has some advice or ideas, it would be just grate, and i’d be really really happy to solve this problem without changing the whole power card.
Cheers everyone,
Lionel
First of all I'm new here, so I'd like to say hello to the DIY community 🙂.
I'm a French musician and like DIY stuff like guitars, effects (analogical), and controlers (arduino / midi /display). But today I have an issue with my non DIY home studio ADAM A7X monitors that I don't know how to fix. So I was thinking that maybe I could find help in this forum.
Indeed, when I switched on the monitors, one of them just “Pok”, and did work no more. I found the input fuse blown and the rear switch set at 115V instead of 230V (kids did that bad joke...).
After changing the fuse with a new one, setting back to 230V, only the tweeter works now (these monitors have separate amp for tweeter and sub).
I investigated further until swapping the power card (card connected to the transformer), with the power card of the other A7X monitor not damaged. Then it worked fine.
Therefore, changing this power card is a solution, but it’s quite expensive (~Card costs about 250€) , so I would like to repair the card myself. To do so I would have to find out which component has been damaged. If any one has some advice or ideas, it would be just grate, and i’d be really really happy to solve this problem without changing the whole power card.
Cheers everyone,
Lionel
This is a known issue. The PWM chip is blown (TDA8920BTH in older models, TDA8953/54 in newer ones -- not compatible, btw), everthing else (rectifiers, caps, etc) normally survives this accident (but needs to be checked, of course).
It is very difficult to replace the chip because it is glued to the PCB (it's on the wave solder side), you need to clip the legs first with a very sharp side cutter (carefully, so as not to damage the solder pads), then loosen the chip carefully with a sharp chisel trying not to damage anything).
Next problem : if it is a TDA8920BTH you'll have a problem sourcing the chip as it has been discontinued a few years ago.
It is very difficult to replace the chip because it is glued to the PCB (it's on the wave solder side), you need to clip the legs first with a very sharp side cutter (carefully, so as not to damage the solder pads), then loosen the chip carefully with a sharp chisel trying not to damage anything).
Next problem : if it is a TDA8920BTH you'll have a problem sourcing the chip as it has been discontinued a few years ago.
DON'T cut the legs, that will damage the PCB, use hot air and plenty of flux.
http://uk.rs-online.com/web/c/semic...8393230425448267374613D5444413839323042544826
http://uk.rs-online.com/web/c/semic...8393230425448267374613D5444413839323042544826
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When you click a product you'll see these chips are unavailable.
Hot air would work normally, but in this product it's very hard to not affect any nearby SMT parts.
EREM 670EP side cutters are specially made for this task, to cut pins of SMT parts, works like a charm.
This is a trusted supplier; TDA8924TH-N2 SemiConductor Make Philips | eBay
Tape or even foil will keep the heat off other components.
Tape or even foil will keep the heat off other components.
Your answers sound good to me!!!! I'm gonna check this out and keep posted.
Thanks very much,
Lionel
Thanks very much,
Lionel
It's indeed a TDA8920BTH. I might be able to remove it from the PCB, and if I can get one new chip, then the most challenging part is to weld the new one properly. That is so so small. 12 legs on ~10mm.
But I will try for sure.
But I will try for sure.
Good afternoon, my name is José Rodrigues, I have a small technical assistance company in Portugal. I have speaker áudio of ADAM , model A7X, with the audio output circuit burned. This equipment was delivered to me for repair, but already stirred by other people who changed some components. I am asking for your help, if I could indicate the original reference of the amplifier IC of the TWEETER. I would like to know the original tweeter reference ,position of the IC is U150. The output IC for the subwoofer is TD8920BTH, already replaced, found in ASWO. I have already searched the web on several websites for the technical service manual, but I was not successful. If someone has the technical service manual, I would not mind buying it as it would be a great help. From now on I am grateful for your help. Thank you, with best regards, José Rodrigues
Hi,
Just to say that I failed replacing the TDA8920BTH.
After replacement, when re-powering the monitor, one cap exploded, so I just give up and order a new power board....
Next time I will be more cautious with working on surface components.
Thank anyway for the help I found here.
Lionel
Just to say that I failed replacing the TDA8920BTH.
After replacement, when re-powering the monitor, one cap exploded, so I just give up and order a new power board....
Next time I will be more cautious with working on surface components.
Thank anyway for the help I found here.
Lionel
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