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Possible Amplifier Issues, Seeking suggestions

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Killa-X

Wed Dec 04 2013, 07:20AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Hello my good friends of 4HV. I seem to be having an audio problem that maybe slowly getting worst as time progresses. First, Some background information.

I got this system at LEAST 6-8+ years ago. It has served me well, has WAY overkill volumn for my use ( 25% knob and 50% computer volumn = i can hear music+sub throughout the entire house ). and the subwoofer as everyone rates it, is overkill so I run it on negative DB.

So. Since I never have to touch the volume at all, I just leave my sound system on, and hid the volume/bass knob unit. So, its pratically turned on 24/7 as it doesnt use much power being idle. With this system, when its turned on/off via the little cute button on the controller, it makes a little click on the speakers. Somewhat expected.

Anyways. So I went off to a convention for 3 days and came back to a change. I noticed pops/clicks from my sound system and figured hmm. My squeeling china powersupply must be going bad or somehow my motherboard is fucking up despite it being a high-end mobo. Which pissed me off a bit. Because every time my furnance kicks on, or people play pinball in the other room ( those machines are known to flick lights sometimes due to the amp draws on solenoids ) my speakers make a quiet click. EVERY time the furnance kicks on or a load is plugged in.

So after i was listening to youtube and had a rather different sound, a what-the-fuck-was-that sound, i was like okay.. i needa know what the heck is up. I powered down my computer and checked everything was solid. Now my computer being off i once in awhile heard stray clicks. so I removed the audio cable, and plugged in my power supply. The moment the power supply sucked its power the speakers ( connected to nothing ) made the same click type sound that it does, when the furnance goes on.

This leads me to pointing the source of the problem, is my sound system, not my computer.

My question: What could cause this. My only guess is the capacitors maybe going bad on the mains filtering side. Making it so whenever a load is applied to mains in the house, that very small flux in power is JUST enough to dip down to basically power off/on my sound system. Though that may explain that clicks when stuff like my furnance comes on, that doesnt explain why sometimes I get the sound randomly even if my computer is turned off. Instead of resorting to "Your stereo system is dieing, just dump it and get a new one" Id rather have some hopes of fixing it because chances are id just buy the same exact sound system...

Found this post online that kinda shows the insides a bit. Found it interesting they use a toroid transformer

Sulaiman

Wed Dec 04 2013, 06:26PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

There are so many possibilities,
my friend at work had a regular 'click' sound develop from his guitar amp,
I gave loads of advice but it turned out to be an electronic analogue watch in his pocket,
the 'new' appearance of the fault coincided with him inheriting his Father's watch !

I suspect external sources of emi/rfi rather than an internal electronic fault,
If you move the whole kit away from the house with a long extension cable or to a different location,
then you can immediately determine if it's an internal or an external problem.

If external then;
.Move everything electrical/electronic far from the amplifier,
.Clamp-on ferrite on every cable near the amplifier,
.go around the house turning everything off,
....zillions more via Google....

If internal then I too would suspect electrolytic capacitors
kits are available for 'classic' amplifiers, you will probably have to buy as a parts list.
Often unit quantities are not available, 5, 10 or 25 is a common 'minimum quantity'
so you can use higher voltage rated capacitors to replace lower voltage rating of the same capacitance,
(higher voltage rating means physically larger, possibly higher esr and much longer life)
Manufacturers always use the cheapest capacitor that will last the design lifetime,
the difference in cost between typical 85C capacitors and good 105C capacitors is negligible compared to the time and effort of replacing them, so buy good capacitors.
Also, since electrolytics are usually for power supply/rail use, and remembering manufacturing,
you can usually use a larger value replacement electrolytic,
e.g. 100uF 35v, 120uF 25v and 150uF 25v could all be replaced with 150uF 35v (or 50v) if space permits
and I find replacing surface mount easier than through hole, so have a go (PM for advice)

Killa-X

Thu Dec 05 2013, 08:21AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Thanks for the tips/information. I want to suspect internal just because in terms of wires, not a single wire has been touched over the past year or two, so for the problem to just randomly come up without any changes to the wiring ( Mind you it just randomly came up out of no where one day ) makes me 'want' to suspect internal. Though for fun, it wouldnt be any harm to pop on a ferrite bead on just see if it has any effect. I just got to get ahold of some, Only ferrites I have are like 12 4x4x1 inch E sections xD

Sulaiman

Thu Dec 05 2013, 06:39PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Use your ferrite E cores to make a GIANT ferrite sleeve,
Should have a double tunnel 6" long ferrite sleeve
put all power cables through one hole
and all signal cables through the other
or maybe some other arrangement?

Killa-X

Fri Dec 06 2013, 05:02AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

I think after work friday I'll rip it apart and see if theres any physical signs of capacitors dieing. I mean the pops on stuff starting up, yeah. you can say must be something on the mains that ferrites can fix. But twice now ( recently today and once a week ago ) Everyone in the house is sleeping, nothing started up, and it literally sounded like someone disconnected the audio jack, rubbed their figure all over it, and plugged it back in. Aka a decent loud pop, grungy noise, and another pop.

And like I said the clicks or w/e can happen when its not connected to anything at all so again, it voids my computer being the issue ( far newer than the stereo system, only a year old ). And since everything "sits" since i got it, the connectors are all brand-new looking so its not a case of dust / dirt.

But with nothing being touched at all, and even getting the rare occasions were i get some nasty sounding crap that can make you jump a little cuz its unexpected / loud, makes me think its on a internal level...

johnf

Fri Dec 06 2013, 09:22AM

Registered Member #230 Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284

check the circuit board with an insulated poush rod. It may be a cracked chip component or leaded one with a bad solder joint.
Lead free hass many problems later in life with jont integrity

Killa-X

Fri Dec 06 2013, 09:43AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

At quick glance with limited room ( wire length restricting me atm ) at a glance nothing seems physically wrong.

havnt really looked at much yet as I just opened it and going to sleep here shortly, i just wanted to see if at a glance anything seemed wrong. Being mounted to the frame of a subwoofer things are prone to vibrations. Which, you think if it was a loose part it would be very repeatable via loud bass hits.

But as seen we simply have power going into the panel that feeds to a round 4" diameter transformer, which then feeds out to the fullwave rectifier. Something I'm not use to seeing, is these yellow round things which, I never at least capacitored my rectifieres like this..unless they're an odd-shape of MOVs..

Rectifier for fun is a KBPC1502 15A 200V rectifier

Am sorta surprised at how little there is to such a thing but then again, i rarely look at amp circuitry. Theres a few SMD parts on the underside, hardly any really, like SMD capacitor across the large filter capacitors and so forth.

What sucks the most is they literally red-loctiled the screws and hot-snotted the SHIT out of this thing. literally there's areas on this DUNKED in hot-snot

With the heaps of hotsnot all over the capacitors and everything else, I sorta ponder if its worth my bother vs buying a new system or even just buying an amplifier to hook the speakers / sub to. Hard to say. xD

Sulaiman

Fri Dec 06 2013, 01:25PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

The yellow things on the bridge rectifier are axial MLCC capacitors, probably 10nF to 100nF
they 'catch' the switching spikes of the rectifier/transformer.

Killa-X

Sat Dec 07 2013, 02:19AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Well after ripping things open and giving a poke at stuff, pushing down hard on the rectifier connectors, taking the fuse out and inserting it back in, doing such with the volume remote ( 10-pin style plug ) etc etc it seems to corrected the problem. So possible something inside, connector wise, wiggled a lil loose after 5+ years of bass. At least, ive yet to hear a problem today. Will see if things maintain this way...

Tetris

Sat Dec 07 2013, 02:25AM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

Won't pushing the connectors damage them?

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