Yamaha DXR15 Powered Speaker Fault LED On

[MobileXT]

No short to C137 and C138 same reading on the working amp also Q106 and Q107 same reading on the working board also same on all reading on all PIN on IC101 same as the working amp.. Where the -55V and +55V generate? is this from the T102? and the T102 controlled by IC101?

[madan1]

No short to C137 and C138 same reading on the working amp also Q106 and Q107 same reading on the working board also same on all reading on all PIN on IC101 same as the working amp.. Where the -55V and +55V generate? is this from the T102? and the T102 controlled by IC101?

SM page 101
T102 pins 9 and 11 are for the +/-55
The same transformer is used for the rest of the power rails, so if you have any power on the secondary side - the smps IC is doing its job.
If the 2x55V coil is not generating power, but the rest power rails are present, the coil might be gone.

[madan1]

Another updates: I received my complete donor for DXR15 amp so I removed the tweeter amp and replaced my old one and now everything is working now two speakers back to life. So Now I like try to fix the donor amp that the problem was not turning on. No green lights missing the -55V and +55V. Also want to fix the tweeter amp. But I like try to fix the AMP board first then the tweeter amp.

If the original unit started working with another twamp board, this most likely means that all of the time there has been audio signal coming from the DSP. It will save you a lot of time (and nerves) if you make sure that you are testing correctly.. just a friendly advice .

SM page 108
The twamp is tda8922. Looks like the protection circuit of the IC is integrated with the rest of the system, so I guess if there is something wrong with its power supply (ig missing rail) the whole unit will be in protection mode. I bet the TDA failed, but still start with the standard procedure - is there power to the ICs on the board (keep an eye which power rail to what is referenced), etc.

[MobileXT]

If the original unit started working with another twamp board, this most likely means that all of the time there has been audio signal coming from the DSP. It will save you a lot of time (and nerves) if you make sure that you are testing correctly.. just a friendly advice .
The CPU must have detected that the tweeter amp is not install. that’s why no audio at HF coming out from the DSP I’m just guessing. I did install the tweeter amp on the working speaker and did duplicate the problem no audio on the Tweeter so I know that the tweeter amp is not working.

SM page 108
The twamp is tda8922. Looks like the protection circuit of the IC is integrated with the rest of the system, so I guess if there is something wrong with its power supply (ig missing rail) the whole unit will be in protection mode. I bet the TDA failed, but still start with the standard procedure - is there power to the ICs on the board (keep an eye which power rail to what is referenced), etc.

All the power supply is there I’m guessing is the audio line is broken somewhere. I already replaced the TDA still same problem so is not the TDA. I will double check again all the power supply on the T-AMP.

[MobileXT]

SM page 101
T102 pins 9 and 11 are for the +/-55
The same transformer is used for the rest of the power rails, so if you have any power on the secondary side - the smps IC is doing its job.
If the 2x55V coil is not generating power, but the rest power rails are present, the coil might be gone.

I believe there’s no power rails on all secondary but will double check again.

[madan1]

For the twamp board, you have floating ground (KG +27.5 in reference to ground) which goes to pin2 on the TDA. TDA pin 1 should be -27.5 in reference to KG (pin2). TDA pin3 should be +27.5 in reference to KG.
TDA pin1 to pin3 should be +55.
On the same board is the oscillator for the TDA - IC503. Again it uses KG for ground. IC503 pin8 to pin16 should be +5V

p.s. check pin 6 MODE on the TDA - it should be >4.2V in reference to KG

All the power supply is there I’m guessing is the audio line is broken somewhere. I already replaced the TDA still same problem so is not the TDA. I will double check again all the power supply on the T-AMP.

Well not many places to lose the audio signal. Only a couple of caps and inductors between the connector and the TDA - L503, L502, c511 and c512. Check their connectivity to the connector and to the TDA. On the output side - only a couple of inductors.
Also, I find it highly doubtful to lose both signals at the same time. If one is missing you will still have o̶n̶e̶ ̶s̶i̶d̶e̶ ̶o̶f̶ ̶t̶h̶e̶ ̶s̶i̶n̶e̶ ̶w̶a̶v̶e̶ ̶a̶n̶d̶ distorted audio on the tweeter*.
If you are sure that the TDA is fine, then start checking the passives around it and the oscillation signal from IC503.

*at least that is what I had, when was troubleshooting similar TDA with a faulty channel.


For the donor unit - if there is nothing on the secondary side, start checking the following on the primary:

sm page 101

voltage across C118
Q106, q107 for shorts
voltage on c184 and c127