Hello all ,
First post 🙂
I have 2 KRK Rokit 5 3rd gen , got them from a friend, he said they both stopped working the same time .
Was Hoping it's the old black conductive gunk and a cleanup, cap replacement and some resistors would do the job but these don't have the black gunk they have clear glue on some parts of the board .
Power supply is testing fine , speakers and working, replaced 2 caps 2200uf 35v but still no audio at all .
Is there any bypass I can check to make sure the TDA chips are working ?
When I touch the leads with my finger while they are connected I do hear some feedback in the speaker.
Was wondering if anyone has any leads where I can start testing.
It has 2 tda7294 , was thinking worse case I'll just rewire the board and use RCA only for input as that is what I use anyway.
Any thoughts?
Thank you all .
First post 🙂
I have 2 KRK Rokit 5 3rd gen , got them from a friend, he said they both stopped working the same time .
Was Hoping it's the old black conductive gunk and a cleanup, cap replacement and some resistors would do the job but these don't have the black gunk they have clear glue on some parts of the board .
Power supply is testing fine , speakers and working, replaced 2 caps 2200uf 35v but still no audio at all .
Is there any bypass I can check to make sure the TDA chips are working ?
When I touch the leads with my finger while they are connected I do hear some feedback in the speaker.
Was wondering if anyone has any leads where I can start testing.
It has 2 tda7294 , was thinking worse case I'll just rewire the board and use RCA only for input as that is what I use anyway.
Any thoughts?
Thank you all .
Attachments
I was able to find online the points on the board I can bridge to get the apm out of standby mode and when I do so I hear a hum and when I put my finger on either of the TDA's I can hear some feedback.
Or alternatively if anyone can recommend a replacement amplifier that I can modify and retrofit into the krk monitor.
I ordered this amp from Amazon SZHFJCTH Audio Amplifier Board with 15W×2+30W 2.1 Channel Subwoofer Amplifier Board, DC12-19V Audio Component amplifiers for Store Solicitation Home Theater Square DIY Speakers and it works fine but just not enough bass .
I ordered this amp from Amazon SZHFJCTH Audio Amplifier Board with 15W×2+30W 2.1 Channel Subwoofer Amplifier Board, DC12-19V Audio Component amplifiers for Store Solicitation Home Theater Square DIY Speakers and it works fine but just not enough bass .
Sorry, I thought I have spotted a crack that would lead to an easy fix: IC replacement.
Anyway, you will need to troubleshoot the board, eye inspection is the first step and you already did it, so now is time to get the schematics and a multi-meter to verify the voltages.
Tonight I will check if I have the schematics in my "collection", you may try Google to find them.
Good luck
Anyway, you will need to troubleshoot the board, eye inspection is the first step and you already did it, so now is time to get the schematics and a multi-meter to verify the voltages.
Tonight I will check if I have the schematics in my "collection", you may try Google to find them.
Good luck
The original board for sure includes some equalization and dedicated frequency/slope for the crossover, using a generic board will not give you good results.
I suggest you to troubleshoot the original board, if you want to try something without debugging you may replace the power ICs which are the most likely part to fail.
A more complicated fix is using just the new power amps you already bought together with the filters/crossover of the original board, again you need to get the schematics to do it.
Thank you so much for your help, Iv been looking around for says now and was not able to find schematics at all .
I also prefer to fix the original board it's sounds better.
So I have 2 of these speakers, each has 2 power amps , what are the chances that they are all bad ?
I was thinking of trying to get them out of standby mode and try to feed audio input directly to the power amp via pins 7 and 8 ?
Do you think that a good idea to test the power chip ?
Is pin 7 and 8 the correct pins to Input audio signal?
I also prefer to fix the original board it's sounds better.
So I have 2 of these speakers, each has 2 power amps , what are the chances that they are all bad ?
I was thinking of trying to get them out of standby mode and try to feed audio input directly to the power amp via pins 7 and 8 ?
Do you think that a good idea to test the power chip ?
Is pin 7 and 8 the correct pins to Input audio signal?
Sorry, I have no experience with those power amps; but you can get their spec-sheet online to verify the pinout.
I will look tonight for the schematics, I think I have some from KRK but I am not sure if they belong to this model.
I will look tonight for the schematics, I think I have some from KRK but I am not sure if they belong to this model.
I'm fairly new to this power amps as well and audio in general, I have attached the schematics for the chip any chance they could take a quick peek and tell me if you think what I mentioned above would work?
And if I could get the krk schematics that would be absolutely amazing.
Thank you again for all your input and feedback.
And if I could get the krk schematics that would be absolutely amazing.
Thank you again for all your input and feedback.
I checked the KRK schematics I have, but they belong to older speaker systems with LM3886 as power amplifiers.
It is hard to repair these devices without the schematics or service manuals, did you try to ask KRK for them?
You did not mention if you have an oscilloscope and other equipment to troubleshoot it. If you do not have it, it will be like a "blind" try.
If that is the case, I will suggest you to measure first the voltage values at the main power supply rails and then at lower regulated rails for the operational amplifiers (the DIL 14 pins ICs are marked TL074 which are quadruple operational amplifiers).
If these two sets of voltage look reasonable (approximately +/- 25V to +/- 35V for the power IC's and +/- 12V to +/-15V for the op-amps), then I will take the risk of replacing the TDA7294's.
It will be very rare that other part has failed besides the power supply or the power amps.
Good luck!
It is hard to repair these devices without the schematics or service manuals, did you try to ask KRK for them?
You did not mention if you have an oscilloscope and other equipment to troubleshoot it. If you do not have it, it will be like a "blind" try.
If that is the case, I will suggest you to measure first the voltage values at the main power supply rails and then at lower regulated rails for the operational amplifiers (the DIL 14 pins ICs are marked TL074 which are quadruple operational amplifiers).
If these two sets of voltage look reasonable (approximately +/- 25V to +/- 35V for the power IC's and +/- 12V to +/-15V for the op-amps), then I will take the risk of replacing the TDA7294's.
It will be very rare that other part has failed besides the power supply or the power amps.
Good luck!
No oscilloscope, I only have a multi meter.
I tested the voltages for the PS , AC and DC they seems to be good.
I also have a working set or KRK 2nd Gen that are working and use the same PS and tired that . Same result.
I'll try to call KRK and see if they will help but they don't even sell the parts for it and the authorized parts seller doesn't have the parts in stock.
I'll try my luck and replace the TDAs 7294 .
If you happen to think of a replacement amplifier you recommend that I can retrofit please let me know .
As a last resort of I can't fix / replace the amps I'll just buy some crossovers and make them passive speakers.
Thank you for your advice.
I think there is a good chance that replacing the power IC's will make it work again.
Good luck!
Good luck!
Did you fixed it? Or not yet? I think your motherboard model is the one without stanby because "CN5" already connected, see pink circle. And I suggest you check another pink circle part "Q5" see if it got 5v power. If not then replace it, the model is "HF" transistor.
