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"Heartbeat" effect in the speaker when leds are flashing

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"Heartbeat" effect in the speaker when leds are flashing

Old 12-10-2010, 12:56 PM
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Gerula
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Default "Heartbeat" effect in the speaker when leds are flashing

I just noticed that when the leds are flashing (before powering up the tank from the remote) there is a "heartbeat" sound in the speaker, synchronised with the flashing of the leds. Is the speaker broken there's a problem with the Rx board?
Old 12-10-2010, 01:09 PM
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BlackCat_2
 
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Default RE:

I think that there is nothing broken in your tank.
Power supply chip-amp sound is very simple - resistance R 33 and a capacitor C 16. You can try to increase the C 16. Or use instead of the resistance R 33 inductor. Or use a voltage regulator like 7805 or 7806
If these sounds are very much you do not like.

But the easiest way - do not pay attention to it

Old 12-10-2010, 01:18 PM
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Gerula
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Default RE: RE:

Thing is I have two Rx13 tanks now, and the difference between them is quite clear: one hardly does the heartbeat (you have to put your earnear the speakerto hear it) while the other is quite loud. (you can hear it from half a meter without being particullary attentive)

I wasable to replicate it by unplugging the turett harness and plugging a LED in the greenand white ports, so it's from the soundcircuit as you said (has nothing to do with theturett wiring, interference from the LED witing and so on)

If you're sure it's not a sign of a failing component I'm tempted toignore it.
Old 12-10-2010, 01:24 PM
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BlackCat_2
 
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Default RE: RE:

In your case with two identical tanks and no identical sounds
May be -

It may have faulty capacitor C 16.
Or is it a bad solder this capacitor

But all the figures of the capacitor and resistance - PCB RX 18.
Old 12-10-2010, 01:31 PM
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Gerula
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Default RE: RE:

C156 is the one soldered on the back of the speaker plug? I don't have C16 marked on the PCB, but this looks like an obvious choice.
Old 12-10-2010, 01:40 PM
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Default RE: RE:

You are looking at the PCB big resistor - the largest resistor in size. The first end of the resistor - to + voltage. The other end - on the second chip contact 2822. Supply filter capacitor is on the second leg too.But at 14 and 13 PCBs. in contrast to 18 - maybe + voltage on this large a resistor through an additional voltage regulator
Old 12-10-2010, 01:50 PM
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Gerula
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Default RE: RE:

You mean this capacitor?
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Old 12-10-2010, 01:56 PM
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Default RE: RE:

And this one - too. See capacitor connected with the second leg of the chip. I, unfortunately, no longer have these printed circuit boards. But in your photo I do not see - connecting the capacitor with the second leg chips and I do not see - connecting the capacitor with a large resistor.
And I was wrong - this big resistor - Soldered to the supply voltage like 18 PCB

Look carefull to enover side of PCB

Old 12-10-2010, 02:02 PM
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Gerula
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Default RE: RE:

Here is the other side of the board.

The big resistor from the back connects to the small C1 and to the larfger C14.
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Old 12-10-2010, 02:09 PM
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Default RE: RE:

Look at capasitor near lower yellow arrow and near the second leg of sound amp. chip.

This capasitor I marked - 1/
Good idea - to make GOOD soldering for Capasitor marked - 2 and transistor marked - 3


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Old 12-10-2010, 02:16 PM
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Default RE: RE:

Yup, that's C14. (you mean the one marked by you as 1, right? ) 2 is a small transistorand 3 is C2

It seems soldered OK on my board. The problem is that I only have a digital ohmmeter, so it will be hard to test the capacitor.
Old 12-10-2010, 03:00 PM
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Default RE: RE:

Well, the capacitor is charging and that's pretty miuch what I'm able to test with my digital ohmmeter. I resoldered it by bringing it closer to the board, everything looks well, but I still have that rather strong "heartbeat". (checked the other soldersas well)

I'll leave the tank opened overnight, maybe someone comes up with an idea. the beat isn't that anoying, I'm just worried it might be a sign that something is about to fail.
Old 12-11-2010, 05:02 AM
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Default RE: RE:

Any ideas?
Old 12-11-2010, 09:43 AM
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Default RE: RE:

You ask - an idea?
Ideas depend on your capabilities in devices for measuring electronic processes.
Let's try
run the Tank and listen to those heart beats.
1.) Disable (soldering out) LEDs are blinking.
Listen to the tank - can not hear the heart beats - There are bad filtering the supply voltage.
Then - watch these electrolytic capacitors. And consider the work of the transistor with a red 3
How to watch the work of the transistor - only through an oscilloscope. This transistor is the voltage regulator board instruction decoder and generator of sounds.
2.) Tank listen - hear the heartbeat.
This is worse. This may mean - somewhere there is a spurious signals in a PCB board sound
Old 12-11-2010, 10:26 AM
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Gerula
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Default RE: RE:

With the turett harness unplugged there's no heartbeat. By soldering out the leds you mean opening the circuit or removing the LEDs but keeping the circuit closed? (this can be achieved by simply shorting the green and white wires on the 8 pins plug)
Old 12-11-2010, 10:33 AM
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Default RE: RE:

I mean - listen to the beating heart without the load current to the wires for the LEDs.
But if you say that without the tower - no sounds of the heartbeat. Try to change the tanks of the tower. If the sounds of the heart changes to the tank - looking for a problem in the tower. Somewhere in the tower has a large current consumption when LEDs flashing
Old 12-11-2010, 10:38 AM
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Gerula
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Default RE: RE:


I already checked that yesterday

I wasable to replicate it by unplugging the turett harness and plugging a LED in the greenand white ports, so it's from the soundcircuit as you said (has nothing to do with theturett wiring, interference from the LED witing and so on)

So, as long as the LED circuit is closed, the pulse current sent to it in order to flash the leds will somehowcreate interference tothe speaker.
Old 12-11-2010, 10:49 AM
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Default RE: RE:

Sorry, missed your reply on experiments with a tower

Yes.
And if not helped to change
capacitor of supplies filter, then find where is this interference to the speaker (audio amplifier) is not always easy.
All the same, it is desirable to have an oscilloscope.
Watch the behavior of the total supply voltage and
supply voltage for each vertical PCBs
Old 12-11-2010, 11:15 AM
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Gerula
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Default RE: RE:

I didn't changed the capacitor (didn't had a spare and shops are closed ) just checked it with the ohmmeter (it's taking charge and going up to infinite ohm) and re-soldered it.

Old 12-11-2010, 11:41 AM
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Default RE:

 OK, I did some more testing, to eliminate a few possibilities:

 1. With the turett 8-pin connector detached, I connected the LED to the green and white wire soldering points of the PCB. Still got the heartbeat.

 2. Muted the speaker (heartbeat still there, only a bit quieter but nothing like what you would expect while going from half volume to zero)

 With the speaker muted, I connected the turret, put the ear on the speaker, and then rotated the turret and raised the gun. Both operations produce interference in the speaker.

 However, as far as I was able to tell, operating the main motors is not causing interference.

 Maybe this can hep to pinpoint the faulty component.

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