Sirius 24 Battery draining

[Firedragon]

Hi

 

I've recently purchased a second hand Sirius 24, but I'm having a few issues. When switching the board on, random lights are illuminated that shouldn't be. Sometimes I get random characters in the display and sometimes it is blank. After a few tries of turning off and on again, the PRESETS ONLY message comes on and normal operation can be resumed. However, anything I have stored in the memory has been wiped out and replaced with random memories. The LS (Lost Store) error also comes up when you switch to programme mode. I have to do a CLEAR ALL in Super User to clear all the memories again.

 

I know this is probably a battery problem, but have replaced the battery with a new one. What I have discovered is that the battery is draining very quickly, after only a couple of hours. I have tried swapping the ICs on the main PCB with a spare set I have, but to no avail. My latest test is to remove the connection to the DMX board. Now I have done this, the battery does not seem to be draining as it was before. (I need to leave it overnight to be sure)

 

So my conclusion is that something on the DMX board is draining the battery... but what? The underside of the DMX board has a white powdery substance all over it and brown stuff around some of the solder connections. Also in places the green board surface has flaked off. Some of the thicker printed metal traces within the board are crinkled as well, as if it has been over hot at some stage. Does this sound feasible? I've attached some pictures (sorry about the quality).

 

I have used the DMX output recently, but had to keep the board switched on to preserve the memories. The DMX seemed to work fine.

 

Can anyone help please and point me in the right direction as to what might be at fault?

 

Many thanks.

[Firedragon]

OK, so I've left the main PCB overnight and the battery has gone from 3.7v to 0.49v. So it's not the DMX board that is affecting it. It must be something on the main PCB itself. Any ideas please?

 

Many thanks.

[iank99]

The "crud" on the underside of your DMX card isn't unusual - it's mostly a by product of the flow solder machine process.

 

If the battery is draining so fast, then it has to be damage to the mainboard tracks around the battery - something is shorting the battery to ground causing it to discharge or a component fail.

 

Looking at a circuit diagram, I'd be looking at D42 to make sure it's still a diode and not letting battery voltage on to the voltage rail that supplies it, D42 is located next to the battery - second resistor up from the zener diode.

[Firedragon]

Thanks, I'll try that.

[iank99]

Oooops - just reread my post - it should be second diode up from the zener!