dB technologies Cromo12 Schematic

[system100m]

Hi, just got a Cromo 12 with the same problem moisesg has. The green led blinks all the time. For the first 10 minutes it sounds well, and then the sound stops and there are crackles heard. Can anyone please direct me to what the defective part is?

[The Dude]

Did you read the thread? There are plenty of tips here. All electronic failures are not the same. When your car breaks down, is it the alternator every time? You'll have to troubleshoot the unit. There's no way we can know what the defective part is. It may not even be a part. It could be a connection issue.

[Jazz P Bass]

There was an old yarn about a computer engineer that got a service call. (back in the '50's)
Got it up & running and handed them the bill.
$3000.11.
What!!!!
11 cents for the capacitor and $3000 for knowing which one.

[shorty_1977]

Hi,
I know this is an old thread and I am also aware that a remote diagnostic is always difficult. I thought I would anyhow give it a try...
We have a FM12 amplifier (this has a DIGIPACK400 as part of the amplification PCB) in our church. Since a while there are intermittend cracks and noises even if no input signal is connected to the monitor.
I already verified all mentioned passive components from this thread - I have not yet exchanged the output IC TDA8950TH as I assume that a defect of this guy would result in no sound at all - or am I mislead here?

Any thoughts or directions to have a look at would be highly appreciated.

[J M Fahey]

Who knows without testing?

In principle:

1) scope the speaker out, check if you see anything weird there, such as DC - oscillation/instability bursts - weirdly chopped Audio, etc.
ANY scope will do, even a humble $15 one.

Just make certain it can handle, say, 50-60V RMS or better to cover what that amp can put out.
If not, also order a 10:1 attenuator probe.

2) almost same thing but with signal: inject a 1kHz tone at the input https://www.mediacollege.com/audio/t...6bit_30sec.mp3 ,(set player to "repeat" because it lasts only 30 seconds) and scope output at different level, with and without load (speakers), anything wild besides a healthy sinewave?
Warning: output is balanced relative to ground, so scope either AUDIO1_OUT1+ to Ground OR AUDIO1_OUT1- to ground.

Not 1+ to 1- because your scope won´t take it.


3) scope signal reaching TDA8950 , TP1 and TP3, which send DAC signals into it.
You may have a very healthy Chipamp just not getting proper signal; if it reaches those test points but does not appear at the output, then Chipamp is highly suspect.

As you see, there is no random guessing parts, but checking functionality.

[Wild_sound]

Hola chicos a todos muy buenas noches consulta tengo una db lvx que al rsto de tenerla.funcionando a bajo.volumen se desaparecen los graves y vuelve alguien me.podria ayudar ya que la.revise por todos lados y no.encuentro que puede ser