Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

[budm]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

Thanks for the follow-up, the fuse may have blown due to the inrush current of the TOROID transformer.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

Hi,
today I changed R301 (22K) to 33K to get a more sensitive audio detection. Last time the fuse blew when I put a 47K there.

The result is quite interesting and unexpected for me.

Before replacing, I did a test with the 22K still in place. I put my AVR at very low volume (-60 dB), then slowly increased the volume until the sub switched on by itself. The result was -48 dB.

With the 33K resistor, the sub switches on as soon as the input cable is connected, even if I set the AVR at -75 dB. Then once I disconnect the audio input, the sub goes in auto-standby after about 2 seconds!
If I keep the audio input cable in place, but I simply switch off the AVR instead, then the sub goes in standby after about 1 to 2 minutes.

Any ideas? I could put the 22K back in place and live with the audio detection as it is, but I am too curious now so I guess I have to continue...

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

I just noticed it was still powered on 20 minutes after switching off my AVR.

I have the impression the audio detection is just hyper-sensitive now and picking up noise even when the cable is connected without an audio signal on it.

And somehow that seems to affect the timeout delay as well (cause switches off 2 seconds after disconnecting the audio cable)

[budm]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

I just noticed it was still powered on 20 minutes after switching off my AVR.

I have the impression the audio detection is just hyper-sensitive now and picking up noise even when the cable is connected without an audio signal on it.

And somehow that seems to affect the timeout delay as well (cause switches off 2 seconds after disconnecting the audio cable)

That resistor change should not affect the timing since once the 555 is triggered it will timed out based on the R/C values, the 22K resistor is for setting the gain of the audio sensing circuit (more gain = less audio level needed at the input) will need to produce the trigger Voltage to start the time.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

the sub was just on, then i switched the avr off and i heard the relay get stuck in a loop. about one click every second. decided to switch off the sub after about 8 clicks

[stj]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

you should fit a 33k preset (variable resistor)
then you can fine-tune it.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

So I tried a 24K resistor and that increased the audio detection sensitivity with 1 dB compared to the 22K.
So seeing that 33K was too much (strange problems described earlier), I decided to put a 30K resistor in place.

With the 30K resistor, when I switched the sub on, and after I connected the audio input with the AVR sending a low volume signal, I heard some foil crackling and then a loud bang. It looks like a cap on the smaller pcb exploded. I have a spare cap for it, so I can take care of that. I just dont understand why the hell it exploded. It is C109 and it is 100 uF.

Pictures of the smaller pcb here(picture 3 and 4):
https://www.badcaps.net/forum/showpo...00&postcount=5

C109 is (was) on the top left of this picture: https://www.badcaps.net/forum/attach...0&d=1414001830

[budm]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

That C109 looks to be a filter cap for pre-amp input section, for 25V cap to blow up, the Voltage applied must have been higher than 25V, since you did not change the cap then wrong polarity was not the cause of the problem.
You should check the DC voltage right at the two legs of the cap. I am not sure if this pre-amp gets the power from the TOROID or from the STBY power supply.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

The spare caps I have are 100uF 35V (not 25V) so I guess that's a good thing.
I'll replace the 30K resistor by a 27K I think, to have less risk of blowing up more stuff.

[stj]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

should have used the 33k preset, you could have just turned it down to 27k with a screwdriver.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

Hi stj, yes I'm aware of that

[stj]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

just saying because it seems a bit silly to keep soldering different resistors in!

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

I found more damaged stuff. The top left transistor on this link, with the heatsink attached to it, blew up as well.
https://www.badcaps.net/forum/attach...8&d=1414001830

I identified it as a B649A. I'll order it but could take a while (cheapest was China post).

Looking at the top of the board, there's a resistor and ZD02 (15V) positioned between the transistor and the group of 4 caps. They look burnt from the explosion.

The resistor is a 15K but measuring it made me confused.
If I measure with the multimeter set to 200M, I measure it at 1 MOhm
If I measure with the multimeter set to 2M, I measure it at 0,11 MOhm
If I measure with the multimeter set to 200K, I measure it at 0,9 MOhm
If I measure with the multimeter set to 20K, I measure it at 0,75 MOhm and when I measure again after a few seconds it's suddenly 0,05 MOhm.
So then I measure at 200K and the result is suddenly 2K...
So I'll replace it with a new 15K resistor.

The Zener Diode I don't know well how to test. I don't have a PSU. I used the "diode test" of my multimeter to test it in-circuit and got a beep signal when measuring both directions. Does this mean that it's shorted?

One of the 4 caps (100 uF 25V) clearly took a hit from the blow. I'll replace that one too and I might do its neighbour as well while I'm busy.

It's good that I quite enjoy doing this stuff, else I might be a bit frustrated by now

[budm]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

It sounds like the power amp section has the problem, that may explained why it blew the main fuse last time, something was failing and finally blew up.
2SB649 is the full number for this PNP transistor.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

hi budm
on the pcb it said b649a so that is what i ordered.
so should i cancel that and get a 2sb649?

[stj]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

i'v never heard of a b649, you sure you didnt order bc649?

[budm]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

Japanese transistors:
2SA, 2SB = PNP
2SC, 2SD = NPN
Very common Japanese number system.
http://www.datasheetcatalog.com/data...6/2SB649.shtml

There should a complimentary NPN that you need to check, the amp has direct couple so when one transistor goes out it can take out lots of parts with it.

[ihopethiswillfi]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

This is what I ordered:

http://www.aliexpress.com/item/10PCS...676909912.html

[budm]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

OK I look at the pictures of the main board, the transistor is used for the linear regulator (Negative), part of the +/- power supply for the OP-AMP, the other transistor should be NPN type for the positive Voltage regulator.
So that explained why the filter cap on the pre amp board blew up due to over voltage when the regulator shorted out and dumped 30~40V on that small filter cap.
There should be 12~15V Zener diode connected to the Base of the transistor, I hope that the ICs are not damaged by the over voltage.

[tom83]

Re: Subwoofer auto on/off: Taga Harmony Platinum SW-10 v.2

Hi Guys
I have a subwoofer taga tsw-90v3, which is damaged. I suspect this is the transformer in the red circle on the pictures, but he does not have any signs on the cover. How can I determine the model of this transformer?