Hi all, first post but cant figure this out on my own.
Amp is quite old Soundstream lilwonder 4.480, I was using it as first 2 channels driving speakers and 3;4 channels small pioneer shallow mount sub.
Problems started as sub was loosing signal, checked wiring and filter switch and could not find any problems, after cycling filter switch many times sub seemed to work in LPF. But after a while sub burned and amp was in protect mode.
So I replaced small power transistors and two D988 transistors, amp is out of protect 🙂 I was happy, but before putting it back in car decided to test it. First two channels are ok. But the 3. and 4. channels seem not to work in LPF, HPF, FULL modes, it works only in BPF, but is crazy loud, gain to minimum, same settings as channel 1,2 except 1,2 running at FULL. 3. and 4. channels are too loud and distorted.
Where to look for problems? I have tested all diodes marked with Z. And small transistors 2sd667 and 2sb647 at channel 3,4 side.
What else to test?
Thanks a lot for any help.
Adding pics of amp:
Amp is quite old Soundstream lilwonder 4.480, I was using it as first 2 channels driving speakers and 3;4 channels small pioneer shallow mount sub.
Problems started as sub was loosing signal, checked wiring and filter switch and could not find any problems, after cycling filter switch many times sub seemed to work in LPF. But after a while sub burned and amp was in protect mode.
So I replaced small power transistors and two D988 transistors, amp is out of protect 🙂 I was happy, but before putting it back in car decided to test it. First two channels are ok. But the 3. and 4. channels seem not to work in LPF, HPF, FULL modes, it works only in BPF, but is crazy loud, gain to minimum, same settings as channel 1,2 except 1,2 running at FULL. 3. and 4. channels are too loud and distorted.
Where to look for problems? I have tested all diodes marked with Z. And small transistors 2sd667 and 2sb647 at channel 3,4 side.
What else to test?
Thanks a lot for any help.
Adding pics of amp:
Do you have a scope or any way to trace the signal through the amp?
Try to get a schematic diagram from Soundstream.
Try to get a schematic diagram from Soundstream.
Unfortunately all I have is multimeter.
When amp is running with input audio signal, normally channels 1 and 2 by measuring at output speaker side with multimeter set to AC it is around few volts. But channels 3,4 Set to BPF are around 20V with gain set to minimum.
Emailed soundstream and asked for schematics, lets see what they say.
Thanks.
/\ Would be a good idea to check for cold solder joints, start with the devices clamped to the sink then move on to larger devices on the board then work your way down. That appears to be an asian built soundstream, I didn't realize the lil wonder wasn't built in the US.
Bad soldering could be all my job 😱
Resoldered all fets, to get amplifier out of protect mode. Replaced shorted ones.
Got an answer from soundstream:
''The schematics are only available to authorized dealers. ''
🙁
Resoldered all fets, to get amplifier out of protect mode. Replaced shorted ones.
Got an answer from soundstream:
''The schematics are only available to authorized dealers. ''
🙁
Measure the DC voltage on the output pins of each of the 8 pin op-amps. Does any op-amp have more than 0.1v on the output pins (1 and 7)?
Place the black meter probe on one of the non-bridging speaker terminals. Place the red meter probe on the point where you need to measure the voltage.
Place the black meter probe on one of the non-bridging speaker terminals. Place the red meter probe on the point where you need to measure the voltage.
Sorry for that!
Most of them have no voltage on pins 1 and 7,
but 3 of them had:
One had 0,38V on pin 1
Two 0,12V and 0,18V on pin 7
Thanks!
Post the DC voltage on all of the pins for the one with 0.38v.
IC#
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
IC#
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
IC#TL072CN
Pin 1: -0.02
Pin 2: -0.02
Pin 3: 0
Pin 4: -15.00
Pin 5: -0
Pin 6: -0
Pin 7: -0
Pin 8: 14.79
Pin1 had 0.38V, but when I pressed it again for measuring, checked other ones, it suddenly was low 0.02 or 0V. Could there be contact problem with this one or its malfunctioning?
Pin 1: -0.02
Pin 2: -0.02
Pin 3: 0
Pin 4: -15.00
Pin 5: -0
Pin 6: -0
Pin 7: -0
Pin 8: 14.79
Pin1 had 0.38V, but when I pressed it again for measuring, checked other ones, it suddenly was low 0.02 or 0V. Could there be contact problem with this one or its malfunctioning?
yes, seems ok audio at Full and LPF.
HPF no sound in one channel.
BPF crazily loud.
All tested with gain set to minimum.
If the gain is too great and distorted, it's likely that you have an open connection in the feedback circuit for the BP filter. This could be a bad solder connection or an open connection in a potentiometer. It's also possible that an op-amp is defective but that's less likely.
Thanks for the help!!! 😉
amps seems to work now as it should.
Got crazy and resoldered half of amp, channel 3;4 side. But still nothing.
Apm had some broken and cold joints see pic. Today worked a bit on input board almost soldered over all points 😀 Some of them as soon as I touched with soldering iron formed a hole, dont seem too good to me.
So after all this mess it started to work correctly 🙂
amps seems to work now as it should.
Got crazy and resoldered half of amp, channel 3;4 side. But still nothing.
Apm had some broken and cold joints see pic. Today worked a bit on input board almost soldered over all points 😀 Some of them as soon as I touched with soldering iron formed a hole, dont seem too good to me.
So after all this mess it started to work correctly 🙂
hello again, now in 2012 😀
Having trouble with same amp.
Most of the time it works ok, but sometimes seems to be changing filter settings from quite normal base levels to something more on highs. But this is not so annoying as a some kind of short circuit what can be heard in front speakers at least those I could check by lowering volume to 0 and this short sound or current is moving speakers. I don't know where to look for a problem because this only happens like once a day, at some moment when car is warmed up. As this problem appears only for short period of time, haven't had luck to stop and troubleshoot, its usually on the way to work.
So it is definitely not stereo, that has been replaced, and managed once to disconnect rca`s so problem could be only in amp or wiring somewhere?
Sorry I try explain as best as I can, and I hate that it is not possible to troubleshoot this for some longer period of time. No worries about speakers, those are not good anyways, have new amp also, just want to know if this could be fixed or let go for parts...
Would like to know what to look for?
Thanks!
Having trouble with same amp.
Most of the time it works ok, but sometimes seems to be changing filter settings from quite normal base levels to something more on highs. But this is not so annoying as a some kind of short circuit what can be heard in front speakers at least those I could check by lowering volume to 0 and this short sound or current is moving speakers. I don't know where to look for a problem because this only happens like once a day, at some moment when car is warmed up. As this problem appears only for short period of time, haven't had luck to stop and troubleshoot, its usually on the way to work.
So it is definitely not stereo, that has been replaced, and managed once to disconnect rca`s so problem could be only in amp or wiring somewhere?
Sorry I try explain as best as I can, and I hate that it is not possible to troubleshoot this for some longer period of time. No worries about speakers, those are not good anyways, have new amp also, just want to know if this could be fixed or let go for parts...
Would like to know what to look for?
Thanks!
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