PSW110 Issues: Static , Heart Beat woes
Comments
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I have a PSW125 12" 300W that I bought in 2016 that started distorting sound about 2 days ago. After initial setup I never adjusted the settings and have not put it through strain, so I am a little perplexed! Anyone know how I can troubleshoot or perhaps even a contact at Polk Audio Canada I can reach out to for support? Any assistance would be appreciated!
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Sigh.... Like clockwork. 3 years later and this same problem presents itself. We'll see if Polk will send me a THIRD amp board for this problem. Unreal.
I like this guy's fix, but at $199 for the amp, I'm partly just leaning to upgrading the sub to something else. Time to go check out the SVS open-box section.......
http://projectgallery.parts-express.com/speaker-projects/polk-psw110-plate-amp-replacement-and-upgrade/ -
I had requested for the PSW110 schematics yesterday. I am extremely happy and thankful to Mr. Kenneth Swauger for sending the schematics in a very short time. @Ken you saved my day. Your help is greatly appreciated.
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POS sub,don't waste your money on trying to repair.If you can't hear a difference, don't waste your money.
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Same issue here. Anyone have links to how to replace the capacitor/ which one to get?
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Same issue here. Anyone have links to how to replace the capacitor/ which one to get?
C38 and C39 are the typical failures. Both are 47uf 63v 105c capacitors
https://forum.polkaudio.com/discussion/175654/polk-psw111-sub-woofer-heartbeat -
I'm tring to repair the PSW110 amplifier board, I need to know the voltage supply over the power stage when psw110 or 111 is running, on the schema i cant find the right value, can somebody help me?
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@Fabio_rm
The reason you can't find the voltage spec is because it is a voltage range. The voltage on the secondary sides of the transformer is controlled depending on the amount of power that is required. As demand changes, the voltage will change.
The AC mains go through a LC noise filter then a bridge rectifier. After the rectifier the DC ripple is smoothed out by the large 150uF 400v cap (c24). This is ALWAYS ON. The positive high voltage DC then goes to the large transformer to PIN 3. The opposite side of the winding, PIN 1, goes through a MOSFET to the negative high voltage DC. The MOSFET, Q12, is controlled by the Vertical SIP Module via J3 PIN 4. THIS IS A HV CIRCUIT as the gate is tied to the negative high voltage DC via a 10K resistor.
The Vertical SIP takes the current demand and varies the frequency of the MOSFET which varies the voltage on the secondary sides. -
I agree, but I fear that, in addition to the IRF14 mosfet tastes and the capacitors to be changed on the main board, the pwm controller module is also broken, but unfortunately in the wiring diagram there is not the PWM controller part to do the controls. That module realizes the feedback of the power supply and the operating principle is roughly known to me, I would like to point out a good article about it (https://audioxpress.com/article/repairing-switching-mode-power-supplies), but I thought they existed only two voltage thresholds, a low when there is no signal and a high when the amplifier sends the signal to the AP, then the feedback keeps the voltage on the final mosfets stable. So I had thought about replacing the switching power supply with a linear one but I wanted to know the voltages. You are instead telling me that the voltage levels are not two but they are dynamic and vary linearly with the request for power, it perplexes me, are you sure or it is as I suppose that there are only two voltage values, one in standby and one when the sub is running?@Fabio_rm
The reason you can't find the voltage spec is because it is a voltage range. The voltage on the secondary sides of the transformer is controlled depending on the amount of power that is required. As demand changes, the voltage will change.
The AC mains go through a LC noise filter then a bridge rectifier. After the rectifier the DC ripple is smoothed out by the large 150uF 400v cap (c24). This is ALWAYS ON. The positive high voltage DC then goes to the large transformer to PIN 3. The opposite side of the winding, PIN 1, goes through a MOSFET to the negative high voltage DC. The MOSFET, Q12, is controlled by the Vertical SIP Module via J3 PIN 4. THIS IS A HV CIRCUIT as the gate is tied to the negative high voltage DC via a 10K resistor.
The Vertical SIP takes the current demand and varies the frequency of the MOSFET which varies the voltage on the secondary sides.
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@bfarnam
I agree, but I fear that, in addition to the fault IRF14 mosfet and the capacitors to be changed on the main board, the pwm controller module is also broken, but unfortunately in the wiring diagram there is not the PWM controller part to do an avaluation. That module realizes the feedback of the power supply and the operating principle is roughly known to me, I would like to point out a good article about it (https://audioxpress.com/article/repairing-switching-mode-power-supplies), but I thought they existed only two voltage thresholds, a low when there is no signal and a high when the amplifier sends the signal to the AP, then the feedback keeps the voltage on the final mosfets stable. The module is unobtainable and i have not schematic to tray reparing, so I had thought about replacing the switching power supply with a linear power supply, but I wanted to know the right voltages. You are instead telling me that the voltage levels are not two (on and off) but they are dynamic and vary linearly with the request of power, it perplexes me, are you sure? I supposed that there are only two voltage values after rectifier and electrolytic capacitor C14 (the one monitored with feedback) , one in standby mode and one in running mode.
I add a detail, before the sub fell silent completely, when it was turned on it did not work for some minuts, after it was fine, this makes me suppose that even in the pwm controller module there is something that is not working correctly and some components was near to death on it.
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@bfarnam
Last update: I just did a test on the fly, connecting a loudspeaker to only one branch of the bridge, the one with the working mosfets, through two capacitors, creating a sort of virtual ground at the output. At low volume it works but the voltage on the mosfets remains about 11 volts, these 11 volts are very stable even when I turn up the volume and the amplifier starts to distort, cause the voltage too low, at the same time this means that the feedback works, otherwise there would be of fluctuations, but the PWM controller does not go to the "ON state" and the voltage always remains 11 volts. I had hoped that, as before the sub was no longer fully functional, the controller would unlock after some minuts but nothing happens. I think it's dead but is near impossible to repair it without schematic and Sonavox dont replay at any email.
I am quite angry to read that people who do not have the slightest knowledge of electronics have solved it by replacing two capacitors and I, who have a degree in electronics and in the past I was a repair technician, instead I have not come out, on the other hand I have never been lucky in anything
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@bfarnam
Anyway, the only way to understand how PWM controller really work is find the schematic, maybe is possible to force the "ON state" with a tweek, i think working on the stage before the optocopuler, but seems to be impossible obtain it from Sonavox -
@bfarnam
I have to apologize, I did other tests and I must admit you were right, the voltage control would seem dynamic.
The controller has an Audio-Trak input and I suspected that the fault was due to the fact that this function did not work, but I continued to remain convinced that it worked as a trigger, i.e. with two operating states, and not dynamically.
That input, through diodes D22 and D23, is driven by the positive half-waves of the cotrophase signals that the TL084 operational amplifier sends to the power stages. So I tried to connect a resistor of a few tens of kohm between the positive of the power supply and the Audio-Trak input, to simulate the signal, and in fact the voltage increased. Then changing the value of the resistance also the voltage changes.
Unfortunately I no longer have an oscilloscope to better understand what happens, but at this point I still can't understan why the amplifier doesn't work, the opamp works well, otherwise the signal would not arrive even at the next stage, the two diodes are good. I can only think that due to a component that is on top of the SIP module it is damaged and that input is less sensitive.
You have to apologize for my bad English and if I am petulant but from what you wrote to me you are the only one here who can have a technical discussion -
After a long time posting here as I was enjoying my HT for last two years without issues. But now I am back(call me selfish
)... Since last morning my subwoofer started behaving strangely. The sub or its amp goes to protection mode as soon as a thump/beat plays. This does not happen if the sub volume set to 50 or less, in that case you cannot feel the bass at all. Tried resetting the audessy (Denon AVR1713) setup just to be sure, changed rca that used for LFE but it is still there. I have to take it to service center, but want to know what could cause this issue.
And secondly this is the 2nd time the subwoofer is not working, before this it went kaput because the amp was dead, got it changed with nominal fee, but now there is no warranty left. So thinking to change the subwoofer depending on the cost of repair. Any suggestion within 20-22K max?
Thanks in advance. -
harveysa801 wrote: »After a long time posting here as I was enjoying my HT for last two years without issues. But now I am back(call me selfish )... Since last morning my subwoofer started behaving strangely. The sub or its amp goes to protection mode as soon as a thump/beat plays. This does not happen if the sub volume set to 50 or less, in that case you cannot feel the bass at all. Tried resetting the audessy (Denon AVR1713) setup just to be sure, changed rca that used for LFE but it is still there. I have to take it to service center, but want to know what could cause this issue.
And secondly this is the 2nd time the subwoofer is not working, before this it went kaput because the amp was dead, got it changed with nominal fee, but now there is no warranty left. So thinking to change the subwoofer depending on the cost of repair. Any suggestion within 20-22K max?
Thanks in advance.
The power supply of the amplifier has a protection based on current absorption, there are some resistances on the source of the mosfet that drives the power transformer, too high a current flowing in the mosfet and therefore also in those resistances, results in an increase of the voltage on those resistances. This voltage is monitored by the PWM controller that drives the Mosfet, if this voltage exceeds a certain threshold the controller stops sending the PWM signal on the gate of the mosfet, and the power supply goes into protection. Too high a current suggests an amplifier fault, but it could be anywhere, or the protection circuit itself is faulty.
