jbl dps-10 subwoofer noise

[harleyman58]

I have a jbl dps-10 sub that when you plug it in it starts buzzing and the longer you leave it plugged in the louder the buzzing gets. the service bulletin that came out says to replace 2 caps and resistors, but the caps I cannot find.
c6 is a 10uf 100v 4% elec radial npe c24 100nf 50v 20%mono ceramic axial.
if anyone knows where I can find these please help. thank you kenny

[budm]

Re: jbl dps-10 subwoofer noise

c24 is for ARC SUB8, SUB 10, and DS-10.
c6 is for PSW-D110, DPS-10.
So is C6 (NON-POLARIZED (BI-POLAR) CAP, 10uF 100V, radial) bad? Digikey

http://www.digikey.com/product-detai...7-3-ND/4328928

Per JBL: In the event you receive a JBL subwoofer corresponding to one of the above models with the
complaint “no output” and capacitor C6 (10uf 50v NPE) is damaged in the amplifier:

Page 15: In the event you receive a PSW-D110, PSW-D112, ARC SUB 8 or ARC SUB 10 Subwoofer with the
complaints “Dead, or No Output, or Motorboating (Oscillation)”, perform the steps listed below first before
any further troubleshooting takes place:
Did you do the re-soldering?
Another common failure in these JBL subs are due to bad Class-D amp module failure.

[harleyman58]

Re: jbl dps-10 subwoofer noise

that cap has to be a 4% not 20%

[budm]

Re: jbl dps-10 subwoofer noise

Where did you get the 4% Tolerance from for the electolytic cap? part list? no such thing as -4% tolerance lytics cap. I sure like to know where JBL buys this -4% lytis cap from, not only that, one page show 50V rating, another page shows 100V rating.
Minus 4%? Other caps are shown as 10%, 20%
C6 30705 10uF 50V -4% ELECTROLYTIC RADIAL NP
SAFETY PART See Page16 ServiceBulletin

Page 16:
In the event you receive a JBL subwoofer corresponding to one of the above models with the
complaint “no output” and capacitor C6 (10uf 50v NPE) is damaged in the amplifier:
Order kit JBL part# 30721 and replace the following included parts:
C6 – (10uf 100v NPE cap) C24 – (100nF 50v cap)
R46 – (47 1/4W resistor) R23 – (20k 1/2W resistor – only on models PSW-D110, DPS-10)
50K Crossover potentiometer – (replace only if necessary on models PSW-D110, DPS-10 - outer nut
should be finger tight plus 1/8 turn with tool to avoid damage)
BTW, same output circuit used in PB10 (C10 (10uF 100V NP) designator in stead of C6)

[harleyman58]

Re: jbl dps-10 subwoofer noise

yes the parts list says 4% on that cap

[harleyman58]

Re: jbl dps-10 subwoofer noise

im just going to put a 10% in it and see what happens.

[Khron]

Re: jbl dps-10 subwoofer noise

I know it's a dirt-cheap idea, but electrolytics in class-D output filters is undoubtedly, and without fail (pun very intended), plain idiotic... <insert facepalm here>

[japlytic]

Re: jbl dps-10 subwoofer noise

I recommend that C6 be replaced with a 100V (or higher) 10uF audio grade film capacitor (not an electrolytic!) for reliability (but would maintain safety) - C6 is most likely to be a low-pass filter for the output since it is associated with series inductors L1 and L2 (and wired directly across the subwoofer voice coil - inductors L3 and L4 are not fitted and therefore jumpered (bypassed) in the circuit).
R4A/B/C are half watt 0.1 ohm units for current monitoring of the subwoofer speaker.

[budm]

Re: jbl dps-10 subwoofer noise

I know it's a dirt-cheap idea, but electrolytics in class-D output filters is undoubtedly, and without fail (pun very intended), plain idiotic... <insert facepalm here>

JBL and many companies are doing that because it is cheap and they can expect it to fail so people will buy a new unit until it breaks again.

[Khron]

Re: jbl dps-10 subwoofer noise

I know, but that doesn't make it any less engineering-ly embarassing Cursed bean-counters...

JBL and many companies are doing that because it is cheap and they can expect it to fail so people will buy a new unit until it breaks again.

[Longbow]

Re: jbl dps-10 subwoofer noise

These parts are not safety capacitors and they are not filter capacitors in the usual sense. They are part of the class D output circuit and selected to work with specific speaker impedance at those lower frequencies. Thus the tighter -4% tolerance. A properly chosen bipolar electrolytic will work fine, especially at the sub-woof frequencies, bypassed by the 100n cap. A large 10uf film capacitor is a better part but probably costs as much as the whole amp assembly.

[budm]

Re: jbl dps-10 subwoofer noise

I never seen electrolytic cap with -4%, I see +/- 20%.
He can try some of these polypropylene caps which JBL should have use them in the first place:
http://www.parts-express.com/Search....itesearch=true

[juliadream]

Re: jbl dps-10 subwoofer noise

4% caps are just specially selected +-20% ones.. they obviously buy big batches of them and test them, the ones which come out +_4% they mark and use for this, the rest probably find their way into other products like passive xovers etc.

Back in the day we called that circuit arrangement a Zobel network, often a cap and a low value resistor. It served a few different functions. It prevented voltage overshoot in the output stage if the amp was run hard with no speaker connected, it also acted as a high pass filter to kill any possibility of high frequency oscillation being set up in the output stage by loads with large inductive/capacitive EMF, another thing it did was to filter stray rf fields stopping things like cb/sw breakthrough.. and finally, and probably why most solid state amplifiers used them.. the cap swamps any capacitance effect from long or weird speaker leads.. early transistor output stages were very prone to oscillation and/or failure due to strange capacitance effects from speaker leads.. I had a couple of germanium amps fail after the outputs went into high frequency oscillation due to long ribbon style speaker leads.. So while JBL might say these components are "critical" I doubt they are.. a nice chunky 10 ohm wire wound resistor and a non polarised cap anywhere from 0.47 to 22µ at enough volts to withstand the output stage will do.. because I bet if you tested one of these "4%" caps after a year or so in service it won't be anything like 4% !!

[classicaudio]

I was just about to buy a used JBL PSW D110 Subwoofer on Facebook Marketplace. I thought I'd check reviews first. Found this troubling thread. It seems that the critical problem was a failure of the output filter cap C6. The recommended replacement was a 10uF 100v NP electrolytic instead of the original 10uF 50V part, plus two other unrelated small parts. Some thoughts, from an engineer with decades of experience designing and fixing stuff: These amps are from about 1998, so age related failures are to be expected, especially in electrolytics. We must use electrolytics because they allow high capacitance in small space at low cost. However, Electrolytic caps will often fail after a few decades of use, so they should be inspected and tested when in doubt. These types of caps use wet chemistry that can change over time and with heating. They are made to leak, not explode, when pressure builds up in the can as they fail. That's why there is a cross on top of every can, it will rupture at the seam and fail gracefully, rather than explode in someone's face (although I have seen them explode too). In this case part C6 appears to fail often, mainly due to under-rated working voltage, but possibly also due to heat stress from high ripple currents. Since it is a small value cap (10 UF), it makes more sense to replace it with a good film cap, which typically will not fail due to age. This C6 cap does hard duty, subject to high AC currents at high frequencies, so it could still fail under stress. But the film cap will do much better. The amp power voltages are +-43.5VDC, so a 50v part is close to it's limit. And there is a high probability of inductive spikes on the output taking the voltage higher. So this part should be overrated for voltage in this application. I might use a 250v rated part.

Another thought is do not use this internal amp, but use external power amp. If this amp is such a pain, dump it and use power from your main amp, or an external auxiliary one. Just a thought. The convenience of the internal amp is useless if it fails often. I have a pair of AR-3a's that I use just that way, driven by a cheap FOSI power amp from the main amp's subwoofer line out signal. I never liked the mid and tweeter on the AR's, but the incredible fundamental deep bass is enjoyable. But I ramble.

Just swap in a10uF 100v film cap, and this amp should last another couple of decades.

Here is a quote from an earlier post of the service bulletin from JBL addressing this issue, and a slice of the amp schematic:

C6 30705 10uF 50V -4% ELECTROLYTIC RADIAL NP SAFETY PART

See Page 16 Service Bulletin

Page 16:
In the event you receive a JBL subwoofer corresponding to one of the above models with the
complaint “no output” and capacitor C6 (10uf 50v NPE) is damaged in the amplifier:
Order kit JBL part# 30721 and replace the following included parts:
C6 – (10uf 100v NPE cap) C24 – (100nF 50v cap)
R46 – (47[K?] 1/4W resistor) R23 – (20k 1/2W resistor – only on models PSW-D110, DPS-10)
50K Crossover potentiometer – (replace only if necessary on models PSW-D110, DPS-10 - outer nut
should be finger tight plus 1/8 turn with tool to avoid damage)