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Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers
Old 2nd December 2017
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Shade Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers

Forward

Hello fellow GS'ers! This is a reissue of a thread that I started over in the Cakewalk forums. It was immensely successful, more than I originally thought possible, as my findings helped many frustrated folks to repair their own crackling, static-ridden--in other words FAILING--KRK Rokit speakers. However, within Cakewalk forum, the thread always seemed a little out of place, though it did garner almost 65,000 views since 2014! The announcement of [insert expletive here] Gibson shutting down the Cakewalk brand, and the fear of a subsequent shutdown of the CW Forum, was the push I needed to port this thread over to Gearslutz.

Thread Summary

There are two (2) fixes outlined in this thread. One is to replace any defective and/or failed electrolytic capacitors, and the second is to clean up and remove the conductive goop that is slathered all over the printed circuit boards. Both issues result in the general failure of the speakers themselves, including the following symptoms:
  • Snaps, Crackles, and Pops
  • Static
  • Hum (60/120Hz)
  • Loss of Bass
  • Complete Loss of the LF or HF Speaker
  • In/Out Fading of Sound

It should be noted that simply replacing the capacitors may not be enough to repair your KRK's to good working order. The root-cause of 99% of the failures, both in components and in the audio quality, is the Black Goop of Death (henceforth as "BGoD"). So this thread, compared to the Cakewalk version, will be organized with cleaning up the BSoD first.


Quote:
"It's all in the goop! Get rid of the goop and get your speakers back!"
Socrates, as transcribed by Plato, c. 410 BC.

Listen to the attachment file for a recorded example of the horrible sound emitted from my Rokit speakers! Does yours sound like this?
Attached Files

krk-static-pops.mp3 (713.8 KB, 8532 views)

Old 2nd December 2017
  #2
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CAUTION: Repair at your own risk. Always be aware of high-voltages which could shock you, i.e. be especially careful around "mains" voltages, amplifier rails, switching power supplies, and high-voltage capacitors. Obviously, you don't want to be touching these while energized, and some capacitive circuit retain a charge.
____________________________________________________

Thank you to the KRK manufacturing team for the Black Goop of Death! This $*%& was intended to "hold down" and protect larger components and wires from vibration. Too bad it caused more failures than its intended purpose!

The Black Goop of Death


I encourage all those who are repairing their Rokits to clean out the goop between components. Seriously, this stuff makes a complete mess. It hard and you must either chisel it out or find another means. Rubbing alcohol doesn't seem to penetrate the stuff, but it does clean up the area after it has been removed. Acetone may prove to be more effective.

Location of previous repair last year, the replacement of the 2.2k ohm resistor, which was cooked. Note the corrosion of the jumpers. I replaced the capacitors (removed) in this area as well, as they both were bulged and had failed. The BGoD got 'em!



All cleaned up and much better!



Another area that was cleaned up. This area also sees raised voltage levels (+/-20V) and the jumper and the components showed signs of corrosion. I also replaced these capacitors as well (not shown).



After cleaning up all the areas shown above, the speaker turned on and sounded good!

So my advice?
  1. Check the boards for corrosion and areas where the BGoD covers multiple components, especially jumpers.
  2. Remove the BGoD using chemicals, a pick or X-Acto blade. In my case, I used a hot soldering iron with a chisel tip + X-Acto + isopropyl alcohol. If you use your soldering iron, then be sure to clean it well afterwards.
  3. Replace burnt resistors and bulged capacitors. Overall, I think it's a good idea to replace all of the power capacitors. The two in the middle are 1000uF 35V electrolytic caps. I replaced them with 50V versions.
Old 2nd December 2017
  #3
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CAUTION: Repair at your own risk. Always be aware of high-voltages which could shock you, i.e. be especially careful around "mains" voltages, amplifier rails, switching power supplies, and high-voltage capacitors. Obviously, you don't want to be touching these while energized, and some capacitive circuit retain a charge.
____________________________________________________

In Post #2 , we've already seen the PCB's up close, so it was assumed that the speaker was already taken apart. However, in this post, we'll start from scratch, but focusing on component replacement.

NOTE: The following guidelines were created on a set of KRK Rokit 6 speakers, but the general disassembly, troubleshooting, and reassembly may be used on all Rokit models/sizes. See next post for the schematic for KRK Rokit 6 (G2) for more in-depth evaluation, component selection, and repair.

First Steps

Turn monitor on it's side as shown and remove the 8, Philips pan-head screws around the perimeter of the backplate.



Take a small flathead screwdriver and pry the backplate from the cabinet. Drop it down to the table.




Replacing Bulged Capacitors and Burnt Resistors

Check out the capacitors and the resistors for trouble. I've included pictures of the particular trouble that plagued my speaker. NOTE: KRK put this awful, crusty black goo all over everything on the amplifier board. Basically, it's glue to hold various components and connectors onto the board, preventing vibrations from disconnecting or breaking them.




The capacitors are used for positive and negative rails (±30Vdc) for the amplifier circuitry, perhaps in an AB class design. The bulging capacitor means that it has failed. The dielectric either dried out and/or the rail voltage exceeded the rating of the capacitor, causing it to fail. In my haste, I did not pre-measure the failed capacitor's voltage while powered on. This would have been a good tidbit of information. However, I surmise that the root cause of the failure is the capacitor, which caused a high leakage-current which in turn raised the rail voltage thereby causing overheating of the 2.2kΩ. Whew! Anyway, we gotta get these garbage components out of here!

Rotate the backplate counter-clockwise into the cabinet, being careful not to overstretch the wires. You could disconnect some of the leads, but why bother. The goal here to to access the solder side (back) of the amplifier board.



Using the soldering iron at the highest setting and the desoldering braid (with a little flux), remove the two, 3300µF capacitors and the failed resistor(s). I chose to not replace the resistor that was OK. No reason to do it. The capacitors, however, are crappola and need to be removed regardless of how they look!



Install and solder the new components to the circuit board. Hopefully you noted the orientation of the capacitors before you removed them! Either look my pictures and/or note the silk-screening on the component side of the PCB. Here are the new components soldered to the board.




Reassembly

Reassemble the speaker by reattaching the backplate. Do not not over-tighten the 8 pan-head screws as the speaker cabinet is made of MDF. The material is soft and the screws can strip easily.
Old 2nd December 2017
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Attachments

The KRK Rokit 6, and perhaps other models/sizes, utilizes the TDA7296 amplifier for the low-frequency (LF) speaker.
See Attachment-1 for this information.

The KRK Rokit 6, and perhaps other models/sizes, utilizes the TDA2052 amplifier for the high-frequency (HF) speaker.
See Attachment-2 for this information.

Attached Files
File Type: pdf TDA7296_datasheet.pdf (241.0 KB, 259 views) File Type: pdf TDA2052_datasheet.pdf (4.03 MB, 219 views)
Old 2nd December 2017
  #5
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Q&A Session

The following are notable Q&A's from original thread and have been ported over into this new thread on GS. I hope you find them helpful.

Quote:
I emailed KRK, or more accurately, Gibson, to ask for a quote for a repair or if they would be able to advise me on components to replace damaged ones with and they passed me on to Focusrite who they said handled their repairs.
Focusrite then replied passing me on to another company who apparently handle their repairs. The third company has not responded -_-


Quote:
You did not explain how you identified which capacitor, resistor or chip is defective. On my circuitry board, there are approximately 40 components (resistors, capacitors, chips), and all seem neat, none of them bulges. So, how should i proceed to identify the failing component(s).
When troubleshooting any faulty electronic circuit/device, start from what can be observed: sights, sounds, smell, touch. Are there any burnt or discolored components? Are there sounds that lead you to a particular section of the PCB or component? Does the problem start and go away after awhile? Does anything smell "hot" or burnt? Do any components feel warm or hot?

This is the stage in which I found the bulged capacitors, which were identified to be a highly likely source of circuit failure...electrically. I say this because at this point, you would have determined the capacitor to be physically failed, but electrically it may still hold up and allow the circuit to operate within its design parameters. So without further testing of the capacitor, such as ESR and capacitance tests, you would never know the complete "truth." So the next logical step is to replace what appears to be failed and retest.

Following up to visual checks on the components, and certainly something to check before ordering components, is to visually check the printed circuit board itself, all solder traces, and all soldered connections. Hairline fractures, cold solder joints, and bridged pads can all lead to problems. To check for loose connections due to loose components, try lightly pressing on components or parts of the PCB while the circuit is turned on, again being careful around hazardous voltages. You may hear the problem stop or get worse. As a follow up, use a magnifying glass to inspect around the PCB. I use a 10x loupe.

In your particular case, you have observed the static coming from the tweeter. So trace the wires from the tweet back to the PCB. In most cases, and good board design, the various circuits (and its components) are grouped together. So chances are, the fault component will be relatively nearby the wires going to the tweeter. I wouldn't rule out an amplifier failure, but hopefully you can replace some basic components for the fix.

Another troubleshooting practice is to check voltages with a meter and/or oscilloscope. But unless you have a schematic and/or component datasheets available (as well as the tools), are versed in electronics, then I would refrain from doing this. It's not for the faint of heart! When a device is powered up, one can easily hurt the components, the board, or themselves!

Quote:
Can you post a link to the 2.2kΩ, 1/2W carbon film resistors that you got from Digi? I don't know which one to buy
thanks!!
CFR-50JB-52-2K2 Yageo | Resistors | DigiKey

Helpful tip from CW member Ampfixer: "If you are going to replace resistors I'd recommend you go with metal film. They are extremely quiet and don't seem to be bothered by thermal drift. I've not opened mine yet because they still work. This looks like a major design flaw at KRK and they should be doing something about it."

Quote:
When I look at the pictures now, it looks like that goop was ejected by capacitors boiling over.
It's not capacitor dielectric unfortunately. That would have been better, and it probably wouldn't have conducted in the manner in which it did. It would have just been messy. However, most capacitors are "dry," including the ones used in the Rokit speakers.

The goop is stuff to hold components and wires in place...like a hard tar. I've seen this used on other boards, but it's mostly a white caulk or straight silicone. Either one is better than this garbage. This stuff probably dries fast, so it was used on the PCB assembly line for that one-of-a-kind, rapid-fire production!

Quote:
You sure?

Positive. That's the BGoD. Eradicate it immediately.

Quote:
I have the Rokit 5's same issue cleaning them up solved much of the crackling but not all so I ordered the components you did and noticed the 5's use the Panasonic 2200µF 50v capacitors not the 3300µF ones I ordered from digikey is it ok to go higher or should I reorder the 2200's?
Since the "BIG" caps are on the main power rails and ground, I think you should be okay with the larger size. It shouldn't affect the operation of the amplifier circuit, nor are they in the audio-signal path.

Quote:
I want to repair my rokit 8's with the same issue but i am a little worried that i might kill them. What are the chances of overheating when soldering with these components? I have killed a few components before because of this but dont want to risk too much with my monitors...
It depends on what you're desoldering and soldering. If repairing integrated circuits (IC's) and "chips," then component package overheating and damage must be considered. Temperature and time are an IC's worst enemy. Many component datasheets specify a maximum temperature sustained for a particular length of time, e.g. 10 seconds at 250°C (482°F). This mainly is a guideline for PCB manufacturers that use solder wave machines and reflow ovens. However, you may also use these maximums while manually soldering and desoldering components. With practice, technique, prep work, and the right tools and temperature, you should be able to solder a pad in a few seconds. For passive components (resistors, capacitors, and inductors), heating should be considered, but it is not as critical.

Quote:
Also I have a hum in one of them along with the crackling, could this be caused by the same problem?
it sounds like ground hum, but when i switch the speakers power supply (swap the IECs, keeping them plugged up the same and with no audio cable plugged in) the hum stays in the same speaker, so i assume it is a problem with the speaker itself...
This, no doubt, sounds like the goop is causing the hum and the crackle. Open up the speaker and inspect for the stupid, corrosive and conductive goop they slathered all over the board. Also check for failed capacitors. You'll be crackle-free in no time!

Quote:
How do you recommend cleaning the goop off? i picked at it a little with a flat head driver and its harder than I expected it to be. Did you just chisel it off?
Cleaning the goop will require something to soften it (chemicals, soldering iron tip, i.e. heat, etc.), then you must scrape it off. Be careful of the traces and surrounding electronic components.

Your biggest concern is actual damage to the circuit board itself...mainly in the melting of the glue layer that holds the copper pad and/or copper trace to the board. If overheated, then this glue melts and the pad and/or trace can lift off the board. Worst case is when it breaks. In my experience, much time needs to be spent working, reworking, and working a pad/trace in order for this to happen. When in doubt, let it cool!

Quote:
So I opened up my monitor. As far as I can see my caps are OK except the one in front of the TDA7296. How should I check the IC condition? I only have a multimeter on hand. Or should I just start cleaning up the black goop?
I would just start cleaning the goop. IMO, don't worry about the amplifier IC. When in operation and powered up, you risk seriously shorting out the component.

Helpful tip from CW member Neilbags: "I'd clean up the goop. Replace the damaged resistors and diodes, clean and test the caps with an ESR meter."

Quote:
Why do these speakers suck so badly?
It's amazing to see the disgusting and negligent spread of the BGoD all over the PCB and components. There is absolutely no reason that crap should be where it is. It's not holding any thing down. It's not preventing vibration of tall components. What a horrible mess of "craftsmanship!" Conspiracy theorists could suspect planned failure/obsolescence of the entire board so the speakers would require repair and/or replacement. Complete joke!

Quote:
...but the most interesting thing I found is I can make the speaker operate normally by bending the PCB towards the bottom side. Works 100% of the time. And if I bend it up upwards towards the component side it creates the noise again.

Czech my vids: Video 1 and Video 2
Good information and a clue! This is a classic symptom of a cold-solder joint and/or or a broken trace.

Quote:
I'm afraid that i've shorted some components somehow because the last time i started it up only the tweeter works. I'll source some acetone then for now.
From my experience, this is actually a symptom of The Black Goop. I thought both of my amplifiers were smoked, but upon cleaning the goop, replacing a few capacitors, the speakers came back to life and have remained strong and problem free ever since.
____________________________________________________

Additional photos and attachments below, depicting the sheer destruction and corrosion caused by the BGoD, courtesy of piss-poor craftsmanship!
Attached Thumbnails
Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-additional_bgod_photo1.jpg   Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-additional_bgod_photo2.jpg   Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-replaced_caps1.png   Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-replaced_caps2.png  
Old 2nd December 2017
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(Reserved for future information...)
Old 8th December 2017
  #7
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was over at cake...

Add me to the list of poor souls who bought these awful KRKs. I should've known better when the first pair of KRK6s I brought home back in '13 had issues and I exchanged for a pair of 8s a few days later. Anyways, both mine are acting up now.

I really haven't used them much to be honest. Im curious if my black goo looks a whole lot 'cleaner' because of the light use or if the black goo issue is a problem that is isolated to a particular batch of black goo they used in manufacturer.

Nevertheless, one of my speakers has no amplification after opening the thing up (had the with weird volume changes for a while) and the other one is just starting to develop pops and very slight volume changes.


'The' resistor is the only thing that I can see that actually looks suspect (see pictures). No bulging caps that I can see.

How did you get the black goo off without taking of the components? I want to use a solvent, but I have read that epoxy removing solvents can also affect traces on the board. However, it looks like there are no traces? Only jumpers???**Edit, looks like the green could be traces?

Can I just dip this thing in a tub of epoxy remover solvent?

Also, the fact that both my LF and HF drivers are not working, this must rule out or narrow down the area where I need to target. Any ideas?


EDIT** So I've been messing around with this some more.
1. I do get sound out of the speakers but it is not amplified at all.
2. I only have 2.5V on red wires at the amplifier board (from both black and earth ground). I couldn't get any voltage from yellow wire.

EDIT***
UGH I was measuring DC voltage... I'm getting more or less appropriate AC voltages, back to the drawing board.

That black goo got in the pin connector for the main power. I think I almost snapped the board trying to get the pin connectors off...

Start testing components i guess... still looking for additional cleaning advice and ways to narrow down components. Everything looks fine and seems to be giving resistances...

-Chris
Attached Thumbnails
Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-20171207_113255.jpg   Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-20171207_113216.jpg  
Old 9th December 2017
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Quote:
Originally Posted by dahleylama View Post
was over at cake...
Welcome!

Quote:
Originally Posted by dahleylama View Post
Im curious if my black goo looks a whole lot 'cleaner' because of the light use or if the black goo issue is a problem that is isolated to a particular batch of black goo they used in manufacturer.
I noticed that as well. It could very well be a better batch of the BGOD.

Quote:
Originally Posted by dahleylama View Post
The resistor is the only thing that I can see that actually looks suspect (see pictures). No bulging caps that I can see.
Which resistor? The one in the center near the red wire? Yes, that one looks like it could be cracked? Do you measure 2k ohms?

Oh wait, I see the one you're talking about! Yes, that dude is scorched, but it can also just be the external appearance. The internal carbon, resistive element may be okay. Looks like it should also be a 2k ohm resistor.

Quote:
Originally Posted by dahleylama View Post
How did you get the black goo off without taking of the components? I want to use a solvent, but I have read that epoxy removing solvents can also affect traces on the board. However, it looks like there are no traces? Only jumpers???**Edit, looks like the green could be traces?
Yes, the dark green lines are the traces. PCB manufacturers coat copper-clad boards, which are typically fiberglass, with a conformal coating which stops corrosion, oxidation, and also doubles as a solder mask.

And the BGOD is only destructive (as it is conductive where it shouldn't be) where it coats exposed electrical connections such as jumpers, between solder joints, or across leads of a component.

Quote:
Originally Posted by dahleylama View Post
Can I just dip this thing in a tub of epoxy remover solvent?
I wouldn't do that. You risk just making a mess out the entire board. I would single out areas that could be problematic, as mentioned above. Then take an X-Acto blade and carve it out. You can also do the old-school hot flat-tip screwdriver (or hot X-Acto blade) technique, i.e. heat the screwdriver over a flame. I've found that heat was the most effective. You honestly don't need to get rid of it all, just the areas where it could conduct electricity used in the power rails and low-level audio signals.

Quote:
Originally Posted by dahleylama View Post
Also, the fact that both my LF and HF drivers are not working, this must rule out or narrow down the area where I need to target. Any ideas?
I don't like the looks of the goop near pin 1 of the HF amplifier (the left IC) where the black wire connects. Looks like the goop could be spanning over a few components.

Also near BOTH suspect resistors. The goop is spanning across the leads of the center resistor and the jumper. This is a big problem area. And the scorched-resistor-area needs to be cleaned up.

Don't worry about the area under the capacitors. Most likely, if the goop has a "lip" to it, then it did not flood underneath the caps. Knowing PCB manufacturing processes, the goop should have been added after board population.
Old 27th February 2018
  #9
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KRK tweeter squeal

Hi all

I have a Rokit that has a LOUD tweeter oscillation So loud, one has to shut the amp down immediately for fear of the driver blowing.

I have recapped the main caps and cleaned the Gob off with Acetone, but I am still getting a 3.4 volt DC offset from the HF amp. I also replaced the 2k2 resistor that had blown.

My next step is to get the PCB washed in an Ultrasonic bath, but it is a quite a hassle to get this done.

Any ideas? Anyone have the KRK schems from the old forum, the links are dead

Many thanks
Peter
Old 1st March 2018
  #10
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Krk volume fade out after few seconds

Hello I'm max and i'm cleaning the board and removing the glue and replacing capacitors since two weeks and the problem still remains the same. actually i'm pretty surprised that they're still working (nothings changed) after my treatment.

but i can not say that they're really working, the problem since i got them used from a friend is: When I turn the power on, everything is alright in sound and volume for about 2-3 seconds. then the volume is fading out quickly to a point where I can turn up the volume knob to max and the speakers are playing as loud as my cellphones ringtone.

one phenomen is that when i turn them off and on again, the speakers volume remains on the normal level longer if I keep them turned off for longer time, but its only a few second difference.

At this point Im quiet desperate and dont have any idea. maybe some of you got one.

max
Old 8th March 2018
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Quote:
Originally Posted by funkymax View Post
Hello I'm max and i'm cleaning the board and removing the glue and replacing capacitors since two weeks and the problem still remains the same. actually i'm pretty surprised that they're still working (nothings changed) after my treatment.

but i can not say that they're really working, the problem since i got them used from a friend is: When I turn the power on, everything is alright in sound and volume for about 2-3 seconds. then the volume is fading out quickly to a point where I can turn up the volume knob to max and the speakers are playing as loud as my cellphones ringtone.

one phenomen is that when i turn them off and on again, the speakers volume remains on the normal level longer if I keep them turned off for longer time, but its only a few second difference.

At this point Im quiet desperate and dont have any idea. maybe some of you got one.

max
Off the top of my head, this sounds like a capacitor and/or power supply failure. The capacitors may be failing and causing the "rails" of the amplifier circuit to shrink, thereby causing a quieter and quieter output over time. By turning the speakers off and allowing the capacitors to discharge before powering the speakers up again allows the caps to start from "zero" again. The funny thing is that you replaced the caps, so this is puzzling for sure.

Can you double-check that the capacitors are connected in the correct polarity? Did you only replace the big, power-supply caps?
Old 13th March 2018
  #12
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First of all thanks @ M.Retra for answering. And youre right i only changed the big power caps, cause i dont have an electric supply shop in my town and i first thought after a few readings that they have to cause the problem. so you think its worth to change all possible capacitators? or is there a smooth possibility to check them with a multimeter?
Old 15th March 2018
  #13
Gear Head
 

I had a 'ghost' repair on this unit.

I cleaned the PCB a second time with Acetone, no fix, still had a 3.4v DC offset on the tweeter.

Got the schematics and I could see exactly where to look, turned on the unit to check the voltages and voila!, no DC offset!

Burnt in for 24 hours and all good, thanks to everyone for their help.

Peter
Old 22nd March 2018
  #14
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Krk volume fade out after few seconds

So again,I changed all the caps on the amp board now and nothing changed, volumes still fading out. could it be a bad resistor. i mean its like that for some reason the amount of energy the amp board is getting from the transistor decreases more and more after a few seconds and then remains on a certain very low level. this f**** speaker is driving me

Does somebody have any guess??? How could I check the tranformator?

sincerly the desperate max
Old 11th April 2018
  #15
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KRK Black sh***t

Hey folks check it out

YouTube
YouTube

This is a channel on YouTube, Australian guy, it wort to watch if you have one of those or experiencing something similar.

Cheers

P.S: Let me know if is not allowed post Youtube Links. Thanks.
Old 11th April 2018
  #16
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Quote:
Originally Posted by funkymax View Post
So again,I changed all the caps on the amp board now and nothing changed, volumes still fading out. could it be a bad resistor. i mean its like that for some reason the amount of energy the amp board is getting from the transistor decreases more and more after a few seconds and then remains on a certain very low level. this f**** speaker is driving me

Does somebody have any guess??? How could I check the tranformator?

sincerly the desperate max



Still looks like capacitors problems, actually, reverse polarity like the other guy said. if not could be related with temperature, that will open a different approach, you should consider the transistors as well the tdas, and I recommend a oscilloscope to check the wave forms

Last edited by danielwotan; 11th April 2018 at 04:55 PM.. Reason: forget to quote
Old 11th April 2018
  #17
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One of my Rokit 8's decided to make a very strange scream, before losing all the high frequencies altogether, last weekend. A quick search brought me here and made me want to fix this myself. As you'd expect, there's the black goo all over the board.

I've managed to scrape away most of the goo and noticed that the same resistor, that M. Retra had changed, was looking a bit burnt and corroded. The capacitors looked fine but I thought it best to replace them anyway.

After replacing the resistor and capacitors, I then went about putting the thing back together. Unfortunately, I still didn't have any high frequencies.

Next I took out the amp from my working monitor and tried it with the broken one and still no high frequencies. So, I now know that I need a replacement tweeter.

As I had already taken out the working amp, I thought it best to get the goo off that one too.

Here's my problem though, one of the resistors next to the HF- cable was that badly corroded that it didn't take much pressure for me to remove it from the board. I've worked out that it's a 10k ohm resistor but I'm not sure on the wattage. Can someone, with some knowledge, please help? It's the resistor that's labelled RL105 on the board.
Old 14th April 2018
  #18
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Dave Jones at EEVblog recently did a couple of videos .....



Old 18th April 2018
  #19
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One of my Daughter's Rokit 5's, started to malfunction, a few weeks ago, the speaker took 30 seconds to produce audio but then was fine, until today, there's a distortion/buzzing in the low end and mid range, and the volume pot on the back of the speaker doesn't work, volume remains the same.
I've just started to relearn electronics after 35 years, so I have a soldering/hot air station and a multi-meter, so I am going to attempt a repair,does this sound like bad caps to you guys?

so I opened it up and had a good look, but could see nothing obvious, not to much gunk, no bulging caps,no corroded resistors
anybody have any thoughts?
Attached Thumbnails
Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-photo-18-04-2018-20-09-36.jpg   Shade-Tree Repair Guide: Fixing the Crackling/Static in KRK Rokit peakers-photo-18-04-2018-20-12-33.jpg  

Last edited by Lorez22; 18th April 2018 at 08:33 PM.. Reason: update
Old 18th April 2018
  #20
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Recent discoveries have shown that KRK used some nasty "glue" on the PC boards of their products. See the recent videos and other information from several sources. The "glue" apparently becomes semi-conductive as it ages and causes many (most?) of the problems that are reported by Rockit users. It seems MUCH more likely that the aging "glue" on the PC boards causing problems than the relatively young capacitors.
Old 3rd May 2018
  #21
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Quote:
Originally Posted by Lorez22 View Post
One of my Daughter's Rokit 5's, started to malfunction, a few weeks ago, the speaker took 30 seconds to produce audio but then was fine, until today, there's a distortion/buzzing in the low end and mid range, and the volume pot on the back of the speaker doesn't work, volume remains the same.
I've just started to relearn electronics after 35 years, so I have a soldering/hot air station and a multi-meter, so I am going to attempt a repair,does this sound like bad caps to you guys?

so I opened it up and had a good look, but could see nothing obvious, not to much gunk, no bulging caps,no corroded resistors
anybody have any thoughts?

Hey Lorez22,

you should definitely try replacing the two capacitors in the middle of the bigger board (should be 1000uF 35V) and while you're at it, measure the resistor between the two big capacitors on the same board. Does it still measure with 2.2k? If not, replace that too.

That's what I did yesterday and it completely fixed my static/crackling noise.
(I live in the Germany and my noise was at 100Hz)

For the faulty volume pot, I have to quote Stephen Scutt from EEVblogs comment section on YouTube:

Quote:
Originally Posted by Stephen Scutt
G2's are also notorious for the volume pot failing. To fix that you desolder it and tighten the lugs with a pair of pliers and bingo, its fixed. Resolder it and your pot is as good as new!!!"
Old 3rd May 2018
  #22
Here for the gear
Thanks, I'll try this weekend
Old 22nd May 2018
  #23
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Howdy, gave this whole thing a shot with my dead KRK (Woofer stopped working) and even after replacing the caps I can't seem to get any sound. Any thoughts on the next thing to replace/investigate? The tweeter is totally fine it's just the woofer.
Old 22nd May 2018
  #24
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Richard Crowley's Avatar
Have you established whether it is the driver or the amplifier?
Do you have another one (like a stereo pair)?
Can you swap the woofer speaker with the other one?

Shotgun replacement of capacitors, especially in newer gear, is vastly overrated as a cure for anything.
Old 20th July 2018
  #25
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Hello,

Thank you for the guidance and clear instructions. 8 year old speakers sound like new! One of my capacitors had a completely rotted pin.
Old 26th July 2018
  #26
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Hey guys my entire circuit board is covered in "battery acid" looking debree and some of the components are melted entirely its looking pretty bad and I was wondering if I can find a way to just replace the entire part as I am not very efficient in repairing individual components (not very tech savvy), I have narrowed the part name down to " RoHS PCBK00022-A " however I cant find this component anywhere and was wondering if anyone had any information or If there was no way to replace it without buying a new speaker, or individually replacing each component on it. Any help is appreciated (:
Old 26th July 2018
  #27
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Richard Crowley's Avatar
Your only option would be to get a replacement board from KRK.*
Companies who make high-volume, mass-market products like those speakers rarely sell internal replacement parts like that.
Their lawyers have convinced them that their liability is too high because they don't know how competent you are to handle the repair.
Plus, since they have apparently gone through many generations, it is unlikely that they keep spares for down-rev versions.

To be sure, there are SOME enlightened companies who are very good at supplying parts and service information.
But they seem to be few and far-between, and KRK has never been known to be very repair-friendly.

So this repair appears to be limited to those who can do component-level diagnosis and repair.
All of the individual components on the PC board are commonly available parts, but the PC board itself is proprietary to KRK.

* Another option might be to get a broken speaker from someone who blew one of the drivers and hope that the board is OK.
Old 27th July 2018
  #28
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I appreciate your quick response, I will look into contacting KRK. I have a local technician who may be able to help me (with older blown speaker parts). I guess I will try him first, Thank you very much!!!
Old 7th September 2018
  #29
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My board is COVERED in this stuff. Is it even worth dealing with? Or should I just focus on the filter cap area?

http://i66.tinypic.com/1dyjgg.jpg
Old 8th September 2018
  #30
Gear Addict
 
M.Retra's Avatar
Quote:
Originally Posted by freewillyb View Post
My board is COVERED in this stuff. Is it even worth dealing with? Or should I just focus on the filter cap area?

http://i66.tinypic.com/1dyjgg.jpg
If you want your speakers to work properly and/or prevent future failure, then YES, you must take care of the goop coating the board. Focus on where it covers a component with exposed leads/wires. For example, the goop that's slathered all over the jumpers and the big resistor (located between the two, big caps--bottom, middle circled area). Focus on areas like that. Don't worry about the stuff that's on top of the caps.
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