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Thread: Anyone know of a schematic for this?

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    Old Timer daz's Avatar
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    Anyone know of a schematic for this?

    I'm going nuts trying to find a schematic for this powered monitor by KRK called a "Rokit powered 5 RPG2". Trying to fix it w/o one is near impossible, so does anyone know of a schematic for it? Please !!! thanks.

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    Old Timer olddawg's Avatar
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    I don't have a schematic, but if it is the same KRK 5 powered speakers I have been seeing there are a few common problems. (KRK is Gibson I think) These problems are common to a lot of these powered speakers of several brands. The most common failure is the power supply filter caps opening up. They underrated the voltage spec because of size and space considerations. You have to be careful replacing them because of double sided boards and they use the cap leads for feed throughs. You also get bad connections because those boards can get rattled pretty good inside those cabs. Most of these monitors are bi amped. I have been able to source replacement speakers and tweeters for some via MCM, but if you do that you better do it in pairs. Working on them isn't really that difficult once you get past the globs of glue on the components, lol. They really aren't that complicated, just tedious and you have to dig in. Hope this helps.

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    Old Timer daz's Avatar
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    Quote Originally Posted by olddawg View Post
    I don't have a schematic, but if it is the same KRK 5 powered speakers I have been seeing there are a few common problems. (KRK is Gibson I think) These problems are common to a lot of these powered speakers of several brands. The most common failure is the power supply filter caps opening up. They underrated the voltage spec because of size and space considerations. You have to be careful replacing them because of double sided boards and they use the cap leads for feed throughs. You also get bad connections because those boards can get rattled pretty good inside those cabs. Most of these monitors are bi amped. I have been able to source replacement speakers and tweeters for some via MCM, but if you do that you better do it in pairs. Working on them isn't really that difficult once you get past the globs of glue on the components, lol. They really aren't that complicated, just tedious and you have to dig in. Hope this helps.
    Yep, gibson. But this one doesn't have double sided boards. (thank u lord !) It's speakers are both good and all the caps check out good as to the diodes. I suspected the ouput fro the low end but i replaced it and still no joy. Can't find any bad joints. But the killer is trying to isolate it when i have no schematic. I do have a 2nd good one tho and i narrowed it down to the output board by putting the other one's good out board in it and it worked. But having checked all diodes and even replaced the low end output i've gone about as far as i can go w/o really spending a ton of time. I suspect a bad joint but they all look really good. Guess i'll just have to set the 2 boards side by side and start checking for differences in readings i get. Just wish i could get my hands on a schismatic dammit !

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    Supporting Member Drewline's Avatar
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    Here is a similar one I have on file. Hope it helps.
    Attached Files Attached Files

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    Drewline

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    Quote Originally Posted by Drewline View Post
    Here is a similar one I have on file. Hope it helps.
    Hi daz.

    Here is the schematic of the RP5G2-A.
    Unfortunately, quality of the picture is bad, but one can
    see that the preamp is similar to the RP6G2.

    Besides this monitors that KRK sells as the RP5G2 model,
    may have different internal schematics (sub-types A, B, etc.).

    In any case, I hope that this information can help you.

    Good luck.
    Attached Files Attached Files

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    Old Timer daz's Avatar
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    Yes, thanks all! I'm busy at the moment but i'll check them out later. Appreciate it !!!!!

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    Old Timer daz's Avatar
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    Damn....the RPG6 one is clear, but it's a totally different circuit with a 15 pin chip in the LF section the 5 doesn't have. The other one is just too low quality to read anything. Maybe i can screen shoot it and do something in photoshop but not likely. This is just my luck ! Oh well, thanks for trying, appreciate it.

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    What seems to be the problem you're having? I get a lot of these for repairs.

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    Old Timer daz's Avatar
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    Quote Originally Posted by diydidi View Post
    What seems to be the problem you're having? I get a lot of these for repairs.
    Well, i seem to have found one issue which is no sound from the LF and that was the 18k resistor in the mute circuit was open. Once i replaced that and the diode and cap there to be safe, it then got signal. But theres still a hum when no signal is present so i shotgunned about 5 PSU caps and still no joy. The thing now works aside from that hum. Problem is, that schematic helps in some ways be with it being so impossible to read much of it and the goop on the board it's impossible to really target certain caps. So i shotgunned the big ones and one or 2 others. There are some non polarized small ones i have nothing to replace. But in any case thats the story at this point. If you have any thoughts i'd appriciate any suggestions.

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    Good on you!!
    For a start, remove all the goop where you can. These have been known to become semi- conductive, and can cause all kinds of shit.

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    Old Timer daz's Avatar
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    Quote Originally Posted by diydidi View Post
    Good on you!!
    For a start, remove all the goop where you can. These have been known to become semi- conductive, and can cause all kinds of shit.
    Done...at least the best i could. I know thats not it tho, but i cleaned much of it off anyways. I think that would only happen in a damp climate, but it's 90 here lately ! (so cal)

    EDIT: if anyone has a schematic i'm still in need, as i can't read much of the one posted. It does help but for example, the must circuit has a open resistor and when replaced it works but with a loud hum which makes me think i need to check the rest of the mute circuit. (aside for the parts i WAS able to find and replace) But i can't because i can't tell what the part numbers are and tracing them is hard to impossible on this board. Right now it hums loudly when i turn it on then gradually lowers till it's about 1/4 as loud. Gotta be some other component that caused that resistor to open up. But i can't check or shotgun parts in that circut w/o knowing what they are.

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    Last edited by daz; 04-29-2015 at 10:09 PM.

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    Old Timer daz's Avatar
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    Heres the schematic posted above, hard to read but at least the circuit configuration is viewable. http://music-electronics-forum.com/a...g2-scheme-.pdf

    I have a question. The LF side works to amplify a signal, but theres a loud hum like a bad PSU cap would make. Looking at that schematic, can anyone tell me what component might be most suspicious if the hum goes away when i hit the right (low freq side) output (TDA2052) with a freeze? I suspected the LF output right away snd changed it twice to brand new ones and now have the original back in and they all do it, plus they all read right. So i don't think it's the 2052. But when i freezwe it the hum stops 1 What would you look at? I have shotgunned every electrolytic, checked every component against a known good board on the other monitor so it's gotta be something thats changing under load.

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    Supporting Member Jazz P Bass's Avatar
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    Mute the TDA2052 input pin (Pin 5) through a 22K R to ground.

    If it still hums, then it's a power supply issue.
    That can be resolved by measuring the Vac ripple right on the power pins. (Pin 2 V+/ Pin 4 V-)

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    Old Timer daz's Avatar
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    Quote Originally Posted by Jazz P Bass View Post
    Mute the TDA2052 input pin (Pin 5) through a 22K R to ground.

    If it still hums, then it's a power supply issue.
    That can be resolved by measuring the Vac ripple right on the power pins. (Pin 2 V+/ Pin 4 V-)
    This is crazy ! I have been banging my head against the wall with this and then i see your post and think ok, that sounds like a great idea and finally i may be able to make some headway. i plug the thing in for the 8 millionth time and before i even go to try that, no hum. So i figure the speaker wire mst not be connected or came off. Nope. I plug everything else in and tested it and the friggin thing is working ! I have no idea why ! I have been screwing around checking things but i don't think i even hit a solder joint since last time it hummed. This would be great, but i fear it will start again. But if i can't coax it into it again i guess it's ok ! This is the kind of sheet that drive me eve nuttier ! I have literally checked every component, solder joint, cable connection, you name it.

    It gets crazier....now i see the good one has some crackling sound and is a lot louder. This crap will be the death of me.

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    Last edited by daz; 05-01-2015 at 05:16 PM.

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    Thanks , Drewline !

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