R-110SW / R-112SW / R-115SW Repair Blog

[BillL001]

13 hours ago, exscape said:

So I finally got the parts, time and energy needed to truly work on the amp, and finished today. I plugged it in and... it makes sound. But not the sounds I want it to make.

 

The speaker cone looks entirely new from the front. Could it still be the speaker that's broken, or is the amp more likely? If so, any advice on how to troubleshoot as I have *NO* idea what could cause this?

The noise is correlated with the bass in the sound playing. E.g. if you play a kick drum, you get a treble-y noise every time the kick should play.

 

Here is what a 85 Hz sine wave played though the sub looks on the SP+ and SP- terminals on the amp.

....

 

Question 2: How warm is the back of the plate (near the output MOSFETs) supposed to get? Mine gets hot (over 50 C) in just a minute or two of testing, doesn't seem right. Perhaps it's due to the speaker issue? Is it meant to get warm enough that it's hard to touch, especially so quickly?

 

From the video, it seems still to be the problem of the amp, not the woofer cone.  When I talked to the Klipsch tech support and let him listen to the sound of my sub, he said any of these clicking sound is the amp problem.

 

What's the spec of the FET you put it on?  I wonder if you use one that has higher power tolerance, it might not get as hot. Similar to that 3W R39 resister, Sinisa just said above he even used a 10W as a replacement, and it still gets hot, so I think we may also need to do for the FET if we want to avoid the risk of overheating. 

 

 

[exscape]

7 hours ago, BillL001 said:

 

From the video, it seems still to be the problem of the amp, not the woofer cone.  When I talked to the Klipsch tech support and let him listen to the sound of my sub, he said any of these clicking sound is the amp problem.

 

What's the spec of the FET you put it on?  I wonder if you use one that has higher power tolerance, it might not get as hot. Similar to that 3W R39 resister, Sinisa just said above he even used a 10W as a replacement, and it still gets hot, so I think we may also need to do for the FET if we want to avoid the risk of overheating. 

 

 

But since the driver/cone sounds the same on a known-good amp, surely it's broken? It also sounds equally off when you test it with just a 9 V battery.

 

I used the original FET, IRFB4227. I don't think higher-power FETs would fit easily.

[exscape]

5 hours ago, exscape said:

But since the driver/cone sounds the same on a known-good amp, surely it's broken? It also sounds equally off when you test it with just a 9 V battery.

I tried the Klipsch amp with a separate cone (from a guitar amp), at low volume, and indeed the amp works! No tinny sound at all, just bass.

 

It gets DAMN hot though. Towards the top, opposite the knobs (where the MOSFETs are) the plate becomes about 70 C (158 F). That's hot enough that it's painful within 1 second of touching that spot. And this is while delivering less than 1 W into the speaker, volume is enough to clearly hear it across the room but not a ton more.

 

A power meter shows it draws 45 W from the outlet.

 

I'm guessing that much heat isn't normal? Or is it independent of power delivered?

Edited February 13, 2023 by exscape

[BillL001]

On 2/13/2023 at 8:24 AM, exscape said:

I tried the Klipsch amp with a separate cone (from a guitar amp), at low volume, and indeed the amp works! No tinny sound at all, just bass.

 

It gets DAMN hot though. Towards the top, opposite the knobs (where the MOSFETs are) the plate becomes about 70 C (158 F). That's hot enough that it's painful within 1 second of touching that spot. And this is while delivering less than 1 W into the speaker, volume is enough to clearly hear it across the room but not a ton more.

 

A power meter shows it draws 45 W from the outlet.

 

I'm guessing that much heat isn't normal? Or is it independent of power delivered?

 

Since the heat is at the control knobs area, that's right behind where that R39 820 ohm reistor is, which is the one that gets burned.  A few posts earlier, someone already mentioned that even with a 10W resistor he used, it was still very hot, and original design of 3W resister surely will burn super hot and just cook the other components nearby, and that's exactly what has happened to so many amp boards.  If you put in a 3W or even 5W resistor at R39 position right next to the FET which is behind the knobs, you are likely getting it just burning there behind the cover plate.  I belive Klipsch had a faulty engineering design there with a tiny 3W resistor in that place. 

[BillL001]

On 2/13/2023 at 2:47 AM, exscape said:

But since the driver/cone sounds the same on a known-good amp, surely it's broken? It also sounds equally off when you test it with just a 9 V battery.

 

I used the original FET, IRFB4227. I don't think higher-power FETs would fit easily.

 

On the FET itself under the IRFB4227 number, there's a 924P code, and online there are also FET with the 914P and 620P numbers, does this different number matter?  Do you know if these different values before the P are interchangeable? Or do have to use the 924P type?

 

[exscape]

On 2/15/2023 at 6:02 AM, BillL001 said:

 

Since the heat is at the control knobs area, that's right behind where that R39 820 ohm reistor is, which is the one that gets burned.  A few posts earlier, someone already mentioned that even with a 10W resistor he used, it was still very hot, and original design of 3W resister surely will burn super hot and just cook the other components nearby, and that's exactly what has happened to so many amp boards.  If you put in a 3W or even 5W resistor at R39 position right next to the FET which is behind the knobs, you are likely getting it just burning there behind the cover plate.  I belive Klipsch had a faulty engineering design there with a tiny 3W resistor in that place. 

 

The heat isn't very close to the resistor, it's exactly behind the MOSFETs, like literally millimeters from where they are mounted. I have a 5 W for that resistor and moved it to the opposite side of the PCB for now. Though the transistor area gets just as hot as the resistor, both are about 70-73 degrees C.

 

On 2/15/2023 at 6:31 AM, BillL001 said:

 

On the FET itself under the IRFB4227 number, there's a 924P code, and online there are also FET with the 914P and 620P numbers, does this different number matter?  Do you know if these different values before the P are interchangeable? Or do have to use the 924P type?

 

No, they don't matter.

I had a look in the datasheet, and as I expected they are date codes and stuff. 9 is the year (2009 according to the datasheet, but perhaps 2019 is also "9"?), 14/20/24 the week, and P means it's lead-free.

[BillL001]

On 2/18/2023 at 2:33 AM, exscape said:

 

The heat isn't very close to the resistor, it's exactly behind the MOSFETs, like literally millimeters from where they are mounted. I have a 5 W for that resistor and moved it to the opposite side of the PCB for now. Though the transistor area gets just as hot as the resistor, both are about 70-73 degrees C.

 

No, they don't matter.

I had a look in the datasheet, and as I expected they are date codes and stuff. 9 is the year (2009 according to the datasheet, but perhaps 2019 is also "9"?), 14/20/24 the week, and P means it's lead-free.

 

Thank you for the comment on the FET!  I will go ahead order one just in case.

 

I finally had the chance today to do the repair - I removed the burned resistor, and the 3 capacitors around it, and replace them all with new ones.  I used a 10W resistor.

 

After putting things back and power it on again, the green LED in the front of the sub blinks once and then went off, and the sub produces no sound when the receiver is pumping sound to the sub.  Bummer! 

 

So it looks like something else shut off the whole circuit, and I will have to re-cap every one on the board, instead of just 3 (I saw someone said he only needed to replace the few around the resistor, so I was hoping I have the same luck and don't have to replace everything. But unfortunately, it looks I will have to replace all the capacitors, since no one knows which one casued the the power to be shut off and no sound comes out from the sub at all.

 

Back to square one - order all the capacitors, and will try it again after getting them... 

 

[Troll]

SPL-150 amp bit the dust.  This one seems like power supply but can’t find burns.  I did notice panel heat even when on auto.  One noticeable thing is no power module heat sinks are bonded to chassis.  Seems like it should have been installed upside down with thermal paste on the heat sinks connecting to panel. Klipsch sent another and doesn’t want this one back.  Spare tire?  While waiting had good luck connecting LFE channel to external amp.  Plate amps seem like such a bad idea, especially with internal heat sinks!

[Troll]

On 2/5/2023 at 9:20 PM, BillL001 said:

Hi All, 

 

After reading this entire thread, as well as watching Mr. ngen33r's 3 repair videos on reparing the R-115SW subs, here's what I can tell:

1. The failure of the amp board is very common on Kilipsch's subs, not only happens to one particular model but many, and the number of failures are very large. 
2. The repair services by Mr. ngen33r seems to be going very slow, if moving forward at all.  Based on vidoes, it looks like it takes little over an hour for ngen33r to repair an amp, so if even if he only works on this on the weekends and repairs a few per weekend, he should be able to fix around a dozen per month. But the waiting list shows that folks requested as early as more than 2 years in Dec. of 2020 are still waiting his sub to be repaired, so may be ngen33r no longer does the repair now. 
3. I have a R-115SW with a failed/burned amp, and it seems there's no scheamtic or complete parts list for all the reistors and capacitiors needed to repair this particular sub's amp.  

 

So my questions are - if any of you know the answer, please offer your comments:

1. Does ngen33r still perform his sub repair services? If not, other than a few on eBay, are there any reliable repair services we can use? Klipsch doesn't offer the repair, unfortunately, and when I called them asking for the options, their tech suppoprt says the only thing they can offer is for me to buy a new amp from them for $300+.   
2. Is there a complete lits of resistors and capacitors to replaced the burned ones on the amp?  For those of us having the solders and other tools, we could potentially try to replace the bad resistors and capacitors, only if we know the complete list of these parts and their specs, which unfortunately, from what I can tell from either this thread or on ngen33r's website, it's not available. The only thing I can see is it's in the 2nd R115SW YT vuideo for a few seconds at 1:16:11.  Can someone confirm these are all the parts we need?  Any recommended brand for good quality of these p[arts, and a good online store to buy them (Amazon)? 

 

Now, related to my particular R-115SW sub's problem, may I ask if any one can comment on what I see on the amp board?

 

1. Where I marked area 1, circuled in red, these seem to be the main failure of that burned resistor, right?

 

2. Where I marked area 2, circuled in blue, there are some glue alike brown stuff at the bottom of the two capacitors, are these factory glues that are supposed to be there, or the melted chemicals ozzed out from the burned resistor or the small cap next to it?  What do you see on your amp board under these two large caps?

 

3. Where I marked area 3, circuled in green, on top of these caps, there's this layer of brown stuff, are these factory glues that are supposed to be there, or the melted chemicals ozzed out from the caps below?  If they are factory glues, I supposed I can leave them there and not replace these caps. What do you see on your amp board above this group of small caps? 

 

Lastly, if you have repaired your amp board, what reference did you use to tell what specs of the resistors and caps at each spot on the board?  In case where the lables on the board are covered by those ozzed on chemaicals, we will have to clearn them up before we can see the soldering spot lables, right? 

 

I wish there's a schematic or diagram showing the specs of each of these parts on the board, somthing Klipsch should provide to us but unfornaturely they don't.  Given the large percentage of their subwoofer customers will run into this problem, Klipsch really should provide us with a repart kit that includes the resitors and capacitors, and a diagram of these parts replacements, so we the customers who can repair by ourseleves could at least to give it a try, instead of paying another $300+ for a replacement amp board.  Paying almost 50% of the cost of buying a new product just for a a few replacement parts, this is like after you buying a $20 grand new car and it breaks down due to some bad parts, and the car company asks you to pay another $10 grand to get it repaired, which no customer would be willing to do.

 

Thanks everyone! 

 

 

 

 

There are a lot of plate amps on parts express website with external heat sinks which seems the way to go/solve this problem if you need to purchase a replacement.  

[BillL001]

Hi Everyone:

 

Latest update...    I finally got all the caps replaced on my board, and got the sub working - sort of...

 

1. I first replaced the burned resistor and the 3 capacitors near it, and hoped that would be enough to fix the board: the 3 green circuled caps were new ones, and I left other caps unchanged.  Notice those circuled in red, has some glue on top, which I thought could be the exploded the cap's internal spured onto them and those caps should be OK, so I didn't replace them, and also left alone those glues on the board below the two large caps on the right side, as I thouht those caps could have been fine and not damaged by the burning resistor.  I installled the new 10W resistor on the back side of the board to avoid its temperature affect the other components on the board:

 

Well, this fix didn't work.  As my last post said, the power-on green LED wouldn't stay on. 

 

[BillL001]

2. So next, I decided to take all the capacitors out, and clean the board as well:  

 

Here I removed all the caps including those two large ones C7 and C8 on the right side, but decided to leave the two on the far left side alone, as I thought the burned resistor most likely didn't impact them:  

 

 

 

 

[BillL001]

3. Next, I installed all the new caps as their replacement: - bought those on Amazon, all Nichicon FG Audio Grade (gold color) or ES Muse (green color) caps:  

 

 

And bought the two large caps for C7 and C8 from Digikey, and they are Nichicon caps as well: 

 

 

So what I put on, are much better than the original caps that came with the amp board. 

 

After putting this back into the sub and tried it again, the power green LED would stay on, but the sub would generate repeated beating sound (repeating "da da da da....") when I swithed to the On mode, which still sounds broken. But fliping the power swith to Auto or Standby, the beating sound would stop.  

 

 

Edited March 26, 2023 by BillL001

[BillL001]

4.  So I decided to replace the other two caps on the far left side as well: 

 

 

With all the caps replaced, I also wrapped the 10W resitor with a copper strip, to divert the possible heat to the alumnum plate in the middle of the amp board to act as heatsink, to keep the resistor cool: 

 

 

Now putting this back into the sub, the sub is working again!  - the power LED would stay on, and there's no beating sound when flipping the switch in the back to either On or Auto or Standby.  So it works exactly as it should be, which is great! 

 

I played some music from YT on TV, and the AVR sending the LFE singnal to the sub worked fine, as I could clearly hear the lows, as well as placing my hands on the sub corne I could feel it's shaking.  So all these are good. 

 

Now the problem...

 

I then played some low frequency sweping videos on YT, and ran into this problem: when I played frequency from 40Hz and above, the sub works fine, but if I play 30 Hz or any lower frequencies, the sub would shut off, and the green power-on LED light will turned off.  I would have to pull the power cord off for a few seconds, and then plug it back on, and flip the switch from Auto to On, and the LED will by on again. 

 

From what I can tell, the only difference in what I put on the board vs what's original at R39 pins, is the 820 ohm resistor I am using now is rated as 10W vs what's the original buned up resistor which was 1 W.  As far as all the caps, they are the same specs, and I made sure they are all installed with the correct palarities. I didn't not change the MOSFET, as I assume what's on the board is still a good one. 

 

So what's puzzling is, why the amp would cut off the power when it plays 30Hz or below frequencies, as I don't think the 10W resistor at R39 could be the cause, because it's the same 820 ohm?  I also doubt the MOSFET would be the cause becuase it's basically acting as an on-off switch to the circuit regardless the frequencies, so it must be one of the capacitors.  But without knowing the circuit design, there's veitually no way to tell.  

 

I wonder if anyone has any ideas or thoughts, or suggestions as to if there's any way to fix this.  Maybe increase the caps voltage ratings, or the cap values? - but that would alter the circuit design, though, right?

 

Thanks!

 

 

[poulmm]

On 12/1/2021 at 2:51 PM, Chicago42 said:

On 11/17/2021 at 1:25 PM, AlphaBass said:

Expand  

Did replacing the caps fix your problem? My amp is now doing the exact same thing.

Hi BillL001 & Co.

I have 2 pcs.  SW-115 i have repaired /upgraded with new caps and a external resistor now mounted on the back side of the alu plate with a m3 Screw. see pic for 820 ohm part number RS:809-8718 for chassis mouting

But one worked the other didn't. Let me explain:

Sub 1: PCB marked: BFS-R115 SW-V1 20140605
On this sub I also replaced the 3 Caps and new 820ohm Resistor.
Error: It would only turn on for 1 sec. then it switch off again.
So I have made alot of meassurement on the working PCB. 
To find out who the Circuit worked. And i quickly found out the U5 - LM324 IC (lower left corner) was missing it 5 Volt supply. Came in for 1 sec. and disappeared right away.
So Please See attached pictures, here is all the Off and On voltages around the signal input detection circuit from the fully working PCB (SUB 2).
I used thise voltages to error search on the bad board. But could not find out why the voltage shot off again. So i have search all over the internet after a schematic but can't find anything on the 112 and 115 sub's.
I came by a side where a user was made a jumper close to the St. By 5 Volt supply. So i also tryed to add this jumper to the PCB, and now it works.
I checked what the Short/jumper do. It add's the +5V st.by constant to the U5 - LM324 +5v Supply Pin.
Can it be a fix from Klipsch ? i really don't know, but its a working fix.

I looks more on the voltages i made on the OK PCB and compared to the Bad PCB. And it looks like there are 3 transistors around the +5 st. by Voltage (2 pin connector) there have something to do with the Supply for the U5 - LM324 IC. But I can't come it closer. But the impontant thing is now the PCB now works with the Jumper fix.
So i was thinking... Could be the "auto" now ain't works anymore. becaus of the Jumper Wire from the +5V st. by. (L3) To R73 pin, so the U5 - Lm324 have constant power. But that is not the case. All is working perfect now.

I wanted to find out what cap. there was the for the shutdown function, and as you can see in the attach picture (handwriten one). The Cap close to pin 14-16 is the one. I checked the time before the sub. auto shutdown, and it takes 15-16 min before it shut perfect down.
You can also measure on the pin 14, 15 and 16 (U5 - LM324) for this function R129 and the cap 100uF is the Tau "time". You and see as soon you add a external signal to the AMP the voltage rise right away on the cap to full +5volt. And as soon the external source is removed the voltage drops to ~3,5 volt and slowly falls down to 0.6V it shutdown.
Looks like a comparator setup here, with a 0,6-0,7V as a ref.

Sub  2: PCB is marked: BFS-R115 SW-V1 20160426
One of them worked perfect after the repair. But have no jumper from L3 to R73, but still works fine. 

Regarding a user saying it was weak below ~30 hz. I have made a measure from 50hz down to 16hz all perfect output power from the AMP output.
Have over ~100-115V 'Ish peak peak amplitude.
Makes sense the power supply is +/-62volt to the amp.
After 16hz it fades out. So they have a filter i would say. Anything lower than 16hz don't make sense anyway. 🙂

Hope it can help others out there, to fix this.
It's not a so nice constructed Circuit. Must i have seen better, in the 25+ Years i have repair stuff. 

Greetings
Poul - Denmark

Edited April 9, 2023 by poulmm
More info

[Cuza26]

Hi guys, i opened mine as it would not turn on anymore and that resistor is swollen and spilled out, the capacitors around dont seem to be affected. The resistors i found are 820ohm, 1-4w, +/-5%. Is this ok or is there different specs? I have a 115. Is there a voltage rating or anything else I need to know? Should i get higher power or just stick to using the same?

[BillL001]

On 4/9/2023 at 3:51 AM, poulmm said:

Hi BillL001 & Co.

I have 2 pcs. ...

... 

 

I came by a side where a user was made a jumper close to the St. By 5 Volt supply. So i also tryed to add this jumper to the PCB, and now it works.
I checked what the Short/jumper do. It add's the +5V st.by constant to the U5 - LM324 +5v Supply Pin.
Can it be a fix from Klipsch ? i really don't know, but its a working fix.
 ....

Greetings
Poul - Denmark

 

 

 

Thank you Poul for your post here!  

 

Could you please provide the URL link to the page where you found that someone did that jumper and fixed the problem? 

 

Just adding jumpers to a PCB without knowing the schematics and its design, could be very risky or even dangerous, because it could cause short circuit, components damage, or in worst case, even fire, if our boards are somehow different from yours. Since you said one of your boards doesn't have this jumper and also works, it shows that there are some variations in the boards, which we don't know exactly what are the differences since we don't have the schematics.   

 

So while I totally believe you in what you said that this could potentially fix the problem, it still would be better if we could see what was the reason and the thinking behind the fix from whoever came up the idea as to why he tried this fix in the first place, if possible at all. 

 

If not, I will give this a try, after getting my replacement amp I ordered from Klipsch, so I could use my original amp as a guinea pig to test this fix, and even if it winds up destroy the amp board, it won't hurt to test this on the exta amp board that I no longer need. 

 

Thanks a lot! 

 

Bill 

 

 

 

 

 

 

 

 

 

 

[BillL001]

Hi All,

 

On the subject of repairing the broken amp board, I am at the point to give up...

 

While it's been fun trying to fix the amp by replacing all the caps and the R39 resistor, this whole "fix-by-ourselves" thing ultimately is not something we can ping hope on, or guarantee it will work, because without seeing the sechmatics, it's like shooting in the dark blindly without knowing exactly what problems we have if it's still not fully working. 

 

In my case of getting the amp half-working after re-cap it, but still having issues of it will shut off after only a few seconds when playing 30Hz or lower frequencies, or play the sub at a high volume (turning the gain knob at mid-way or higher), it feels like I am hitting a dead end, since there's no schematics to help us to analize further, and no clear directions as to what's the cause to the problem and what's the right fix.  

 

I posted a question about my repair still having this issue to the comments section of one of Mr. ngen33r's repair videos on YT, and surprisingly he replied, and asked if setting the volume lower would keep the sub going.  But after I provided the answer to him, I no longer getting any further reply from him.  I don't blame ngen33r for not providing timely answers there or no longer coming here to help us, since he has no obligation to answer any of us, but the mere fact that we can't just keep waiting for weeks or months to get answers if our repair doesn't fully fix the amp, it made me to doubt the feasibility and validity of trying to fix this by ourselves without the schematics and without any help from Klipsch.

 

So with this realization, I decided to bite the bullet and go ahead order the replacement amp board from Klipsch, just to get the sub working again, so I won't waste all the money that bought the sub, and at least bring it back to full working condition and getting some use out of it.   

 

I may try the method of adding a jumper later as Poul suggested above, after I get the replacement amp and not concerned with potentially frying my original amp with an additional jumper. 

 

This whole experience of getting no support from Klipsch, for a faulty product design that they refuse to take the responsibility and have done nothing to help the customers, should be a lesson for all of us that we should never ever buy another Klipsch subwoofer again!  Such as bad company with pathetic customer support and service! 

 

Wish many of you have a better luck than me in your repair effort!  

 

Edited April 12, 2023 by BillL001

[Troll]

Many years ago I bought a 15” sub from klipsch and the amp failed.  Back then they said it was vibration.  The new amp had more vibration goo.  Now I got a new SPL-150 and the amp failed and I am 2 for 2, and both times Klipsch didn’t want the broken amp back.  With all the goo it seems basically non-serviceable.  The old sub still works, repeat failing dust cap aside.  The spl-150 amp had a hot panel prior to failure.  Other panel amps have an external heat sink, but maybe the heat was caused by a failing component.  No odor to board though.  
 

It would be interesting to have a list of test points to see whether it qualifies for repair.  Maybe the vibration goo makes it a throwaway.  Manufacturing automation can make these complications cheap and easy to produce, but hard on regular humans!

 

However the TPA3255EVM runs so cool in comparison with fewer parts it seems Klipsch just needs to move on to greener pastures. 

 

Cheers!

Edited April 12, 2023 by Stephen Buck

[BillL001]

19 hours ago, Stephen Buck said:

Many years ago I bought a 15” sub from klipsch and the amp failed.  Back then they said it was vibration.  The new amp had more vibration goo.  Now I got a new SPL-150 and the amp failed and I am 2 for 2, and both times Klipsch didn’t want the broken amp back.  With all the goo it seems basically non-serviceable.  The old sub still works, repeat failing dust cap aside.  The spl-150 amp had a hot panel prior to failure.  Other panel amps have an external heat sink, but maybe the heat was caused by a failing component.  No odor to board though.  
 

It would be interesting to have a list of test points to see whether it qualifies for repair.  Maybe the vibration goo makes it a throwaway.  Manufacturing automation can make these complications cheap and easy to produce, but hard on regular humans!

 

However the TPA3255EVM runs so cool in comparison with fewer parts it seems Klipsch just needs to move on to greener pastures. 

 

Cheers!

 

The replacement amp that Kilpsch sells to customers to repair the R-115SW subs, is the SPL-150 amp, which Klipsch claimed to be compatiable with the R-115SW sub. I just got mine in the mail after ordered it with a discount Kilpsch gave me.  

 

Too bad to hear that this amp board also getting hot, and yours also broke due to some internal fault. I tested mine, and it appears to be OK, although time will tell if this one is going to last or not. 

 

The new SPL-150 amp had silicon glue pured all over the capacitors and resistors, so it's not going be repairable by us the users like we have tried for the original R-115SW amp.   If this replacement amp burns out again, we have no other choices but either order another amp from Klipsch yet again, or throw out the entire sub for good. 

 

 

[BillL001]

Last update on repairing my R-115SW sub amp: 

 

I got my new replacement amp from Klipsch, so I decided to try the fix that Poul suggested: adding a jumper between L3 and R75 (he had a typo in his post saying it was R73) - between the two red cicled spots: 

 

 

I used a thin copper wire as the jumper: 

 

 

It was harder to solder the jumper on because of the tight space, and I accidentally touched my soldering iron with the plastic wite plug next to it and burned off some plastic on the plug.  Fortunately there's damamge to the wire, so it didn't affected the wire and the plug.  

 

Anyway, this method unfortunately did not fix the problem for me.  It actually somehow disabled the amp. After plugged in the amp to the sub, the front LED is on, showing it got the power, but when playing sound through the AVR, the sub stayed quiet and did not do anything - no sound, and the woofer corne did not even move, while the power LED was on. 

 

I pulled off the jumper wire and tried it again, the sub was back to its half-working state: it plays music as normal, but when I feed low frequecies sweeps from 5 Hz - 1K Hz from the AVR, the sub stopped playing when the 20 Hz frequency was playing, and the power LED turned off, exactly like its state after I replaced all the caps.  

 

Since I got the SPL-150 amp from Klipsch, I swapped that one in, and the sub worked perfectly again like new, and playing frequencies sweeps did not run into any problem, as the sub started produce sound at 10Hz, then 20, 40, 60, 80 Hz, and so on, all the way to about 100 Hz, before the L/R and center speakers started taking over.  

 

I suppose this would be the end of my attempt to repair the original R-115SW sub's amp, given that there's no solution available on how to get it to work for playhing frequencies from 10 Hz - 30Hz with the volume setting at 40% or higher on the gain knob without shutting itself off.  

 

I am going to use the sub with the SPL-150 amp as the replacement, until someday it burned out again. If it happens outside of its warranty period, I will just throw away this whole Klipsch junky thing, and go get a SVS or Hsu or Polk subwoofer. 

 

Thanks everyone!