KRK Rokit 8 G2 extremely low volume output.....

[Soundfreak87]

Hi everyone!

I'm wondering if any of you knowledgeable people can help me.

I have a pair of KRK Rokit 8 Gen 2's.

One of the monitors has really low volume... I have to put my ear right up to the speaker cone to hear the audio and this is with the volume pot on full blast.

I have taken out the amplifier to look for bad caps and I have replaced all the electrolytic caps on the preamp board with audio grade Nichicon caps and tested all the rest of the caps on the board with an LCR meter and they check out within spec. (all caps were removed from circuit whilst testing).

I think I have narrowed the problem down to the pre amp board because when I was checking for voltages, I touched one of the legs on a JRP4580D operational amplifier (this is the 2nd op amp in circuit) and I had loud sound like I have touched the end of an RCA cable whilst plugged into the speaker jack. I then took an 3.5mm to twin RCA cable splitter and plugged it into my iPod. I grounded one side and touched the same pin on the JRP4850D (which I believe is the 'out' leg) with the other RCA and I had good, clean, loud, normal sound but with no volume control as I believe the problem lies between the RCA connector, volume pot and the op amps.

I have also checked all zener diodes on the board. I haven't paid much attention to the resistors though as none of them are burnt up.... should I be paying attention to them?

There's 6 of these JRP4580D op amps on the pre amp board.

Does anyone have any idea what could be causing or has had the same issue and has repaired it?

Could it be the 4580D's? I can get these for around 27p each from an electronic component distributor, however I'd rather know what exactly is causing this issue and replace that rather than replacing everything.....

I have attached a diagram with the pin out of the op amps on the board and the pin that gives me sound is (IN2+)

Any guidance will be appreciated!

Thanks in advance.

[Khron]

Re: KRK Rokit 8 G2 extremely low volume output.....

The easiest way would be with the schematic, and a signal tracer (ie. a sinewave on the input, and a probe going to a small amp & speaker; you follow the signal path with said probe).

So you're getting a strong signal at the "IN2+" of the suspected opamp, but not at "Out2"?

[Soundfreak87]

Re: KRK Rokit 8 G2 extremely low volume output.....

The easiest way would be with the schematic, and a signal tracer (ie. a sinewave on the input, and a probe going to a small amp & speaker; you follow the signal path with said probe).

So you're getting a strong signal at the "IN2+" of the suspected opamp, but not at "Out2"?

Thanks for your reply Khron,

I thought I was on my own for a little while......

So I took a small 5v usb set of speakers I have and attached my multimeter probe to the signal wire and grounded the earth and it worked well. I was able to trace the signal to the 4580D op amp, there was signal going in but nothing coming out (I think).

but....... as I was about to start to investigate into it further, the TDA2052 transistor which according to the schematic I have of the boards powers the tweeter, burst into 2 pieces with a loud bang . I didn't short anything, however I have noticed in the past that the TDA2052 gets reallly hot (real hot like I burnt my thumb on it once) and the TDA7294 which powers the woofer only gets warm.

The transistor for the woofer is working still intact.

I have placed an order for the 4850D op amps and also the TDA2052.

Is there any reason to why on earth that TDA2052 burst like that?

By the way, both the transistors were attached to the heatsink when this happened.