harmon/kardon sub-ts14 makes high-pitched squeal sound

[exetico]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

Hi'

Sounds a bit like the problem i'm struggling with.
Video: (Warning: High sound)
https://streamable.com/dllx

Any suggestions? I'm going to look at the hardware now...

[axlmastr]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I found a company in Illinois on ebay that does electronic service work. They have individual listings for all of the various plate amplifiers like the subject of this post. They offer to fix it like new again for $145. I have to "Buy it Now" and they give instructions where to ship. I ship it there at my cost and they include return shipping in the sale price.

I know the idea is to repair it yourself, but this is an option.

[lexwalker]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

@lexwalker:

Would you be able to point me to the cap(s) that I need to check?
Sorry my hands-on experience is rather limited, but I can check a cap and solder if needed

Look at areas around U203/A and U204/A, also subsequent areas after that such as components surround Q206, Q207 and U203/B. Try checking the components around there, and also replace all the capacitors there (especially that C300).

[fastvideo]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I spot..... degraded glue!

Lexwalker is right.

First thing you should do is remove and clean all rusted glue between connections and pins of each components on each board.
then the Caps.

[tpr]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

@lexwalker:

Would you be able to point me to the cap(s) that I need to check?
Sorry my hands-on experience is rather limited, but I can check a cap and solder if needed

@budm:

I don't hear any noise when the unit is on.

[lexwalker]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I'm in the same club here folks! LOL. I've included some pics of the crispiness that happened. Looks like I'm gonna have to replace the PCB 104ds15000 for sure and possibly the PCB 104sub15000. However, here's the problem. JBL/Harman doesn't sell the PCB's alone anymore, they are only available as part of the entire replacement Power Amp Class D Module 012-7500-00022 which goes for $177 and change. Would it be worth the trouble to have a custom PCB made and then just replace the bad components after testing?

From the pictures, easily can see degraded glue (again!), blackish PCB area due to heat from those naked heatsinkless transistors and leaking capacitors. Would suggest checking those transistors (possibly replacing them as well) and replace all capacitors on that board.

Hi guys,
I'm new here, hoping to get an opinion of the experts.
Piggybacking on this thread as we're talking about the similar hardware.

I have SUB TS15 which kept off (power switch off) during my recent vacation.
When I came back and turned it on, the sub is working fine when active, but as soon as it goes to standby (led change from blue to orange) it starts creating a low frequency thumping sound which can be only stopped by either starting the music again or turning the sub completely off.

To mitigate the issue I switched it to "always on" mode so that it never goes to standby.

I attached a SM in case someone wants to take a look.

I appreciate any hints on how to resolve this problem.

Had the same problem on different speaker system, and the source of the problem was a badcap on the secondary feedback section (initially I was looking around the primary side feedback area plus changing the opto-isolator, then attention went to the control section)...

[budm]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

As you can see in page 31, when unit goes into mute/Standby mode, Q102 is turn ON, which will turn off Q103 and Q104. So, do you hear any rumbling when the unit is set to always ON (buy the way, when it is in standby, the power amp and the preamp are still getting power)? It can be due to unstable power, so you need to check the DC voltage on the +/- power supply filter caps, it can also be that Q102 is not being completely turn on by steady DC but with low frequency DC.

[tpr]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

Hi guys,
I'm new here, hoping to get an opinion of the experts.
Piggybacking on this thread as we're talking about the similar hardware.

I have SUB TS15 which kept off (power switch off) during my recent vacation.
When I came back and turned it on, the sub is working fine when active, but as soon as it goes to standby (led change from blue to orange) it starts creating a low frequency thumping sound which can be only stopped by either starting the music again or turning the sub completely off.

To mitigate the issue I switched it to "always on" mode so that it never goes to standby.

I attached a SM in case someone wants to take a look.

I appreciate any hints on how to resolve this problem.

[budm]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

You may be better of with sub-woofer plate amplifier as the replacement instead 9if the speaker is still OK, just have to modify the cabinet.
http://www.parts-express.com/cat/sub...amplifiers/332

[mightyeskimo]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I'm in the same club here folks! LOL. I've included some pics of the crispiness that happened. Looks like I'm gonna have to replace the PCB 104ds15000 for sure and possibly the PCB 104sub15000. However, here's the problem. JBL/Harman doesn't sell the PCB's alone anymore, they are only available as part of the entire replacement Power Amp Class D Module 012-7500-00022 which goes for $177 and change. Would it be worth the trouble to have a custom PCB made and then just replace the bad components after testing?

[ben7]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

Replace the bipolar electrolytic capacitors on the power amp module (the one on the heatsink). I other threads with similar power amp modules, which had bad capacitors.

[lexwalker]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I took apart the boards from the encasing.... found the Service Manual online... but after examining the board with the naked eye, I see no obvious issues.


Any help would be greatly appreciated!

I spot..... degraded glue!

[gtdavelo]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I took apart the boards from the encasing.... found the Service Manual online... but after examining the board with the naked eye, I see no obvious issues.


Any help would be greatly appreciated!

Dave

[gtdavelo]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I'm following this thread ever since my gf's subwoofer has the same issue... I'm stuck at trying to remove the board and PSU from the wooden shell... all screws were removed... yet no luck.... any help would greatly be appreciated

Dave

[budm]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

You should verify that your meter's battery is OK, the would have explode with that much voltage on it and also blow the main fuse.
By the way, how did you measure the voltage on the main two caps? Did you measure directly on each pair of the cap's legs?
This is BI-POLAR power supply that puts out +/- with ref to ground. The R502 is for supplying the -15V linear regulator (regulated by Q502 and the ref Zener diode D502 which is also the ref for the +15V power supply.
These +/-15 are for the Op-amp. You need to check and see if you have heavy load or short at the Emitter of Q502, may be feeding shorted circuit. You also need to verify of the Q502 is not damaged.
Just set the meter to 200 Ohm scale and check the resistance between the Emitter of Q502 and Ground.

[lti]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

R502 connects to the collector of the TIP32C transistor. Checking the other components connected to the transistors might be a good start.

If the caps really had 142V across them, they would have blown up (unless they were open or dry).

[axlmastr]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

I got your message and decided to give this unit some AC and see what measurements I could get. When I flipped the rocker switch for power the relay clicked as usual and within 10 seconds I saw thin smoke rising from beneath the Toroidal coil. It appears the resistor (R502) that was originally charred and detached (the one I resoldered) began to get hot and smoke. I did get a chance to measure the terminals across the two Su'scon 4700uF 80V caps and they measured 142 volts! Could those caps cause a dead short? Where's the 142V coming from? The caps are rated for 80V.

[budm]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

Yes, you should also check the DC filter caps, JBL had the same problem and suggesting to check the main DC filter caps.

[axlmastr]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

Thanks for the reply budm. I see them on a riser board up from the power board. The board is marked "104DS15000 Amplifier". A Google search shows this is also on a JBL model. The caps are covered in a hard brown glue with a horizontal ferrite cored choke in between them. I cut the glue and peeled them back to check the location number you gave and the values. They are also marked SOLI & 20%. How should I check these as they are visually okay?

What do you think about the other poster's ideas of replacing the two huge Su'scon 4700uf 80V caps? They look fine. I haven't measured across them.

Or replacing the resistor R502 that as I mentioned in my original post had one solder joint (closest to the monster 4700uF cap) melted and charred. There are some brown heat marks in the PCB beneath R501 & R502 as well as Q501 but I have seen these brown marks before on other PCB. Are the brown marks a sign of component stress because of impending failure?

Realize I got this sub to look at after a lightning storm had knocked it unconscious. I took it apart and found the R502 lead had disconnected from the PCB at the solder joint and the lead and solder joint were a bit charred. I cleaned the PCB area trimmed the lead so it was usable and re-soldered it. At this point the unit powered and the high frequency noise was present.

[budm]

Re: harmon/kardon sub-ts14 makes high-pitched squeal sound

Did you check the C16, 17 10UF non-polar 100v? they are part of the ClassD output filter network.