Repairing a KRK V8 Series 1 Monitor

[jasonallen19]

Hi All,

First, I know that KRK was sold and no longer supports these speakers. I have no chance of sourcing help/parts from them. So I need figure out how repairable this speaker is.

A close friend of mine (Tim) inherited two KRK V8 Series 1 monitors. We got them setup, and after a while he noticed one of them was a bit more noisy than the other one.

A few weeks later he said the noise had gotten worse, the speaker was super hot and he was concerned. So I came by and checked things out. One thing I noticed was that the sensitivity setting was at +6db, and they got very loud, very quick. Very touchy. I figured since he had a good strong input signal we should adjust the sensitivity so they were less jumpy and we could spread the signal to noise ratio out a bit and get rid of the noise. This worked great for the speaker that was ok. Set the sensitivity to 0. It was less jumpy, but still sounded amazing once it was turned up.

When I went to adjust the sensitivity on the noisy speaker, the actual dial bent in (the pins bent and the dial folded in), the speaker freaked out and cut out. Other than a popping sound from toggling the tweeter’s crossover switch, nothing. And the backplate started getting super hot, really quick.

I took the speaker home with me to try and diagnose it further.

Here’s what I found so far.

Pic of amp assembly.

Tweeter is blown. I think it blew when things shorted out. Shows 0ohms on meter, where as the woofer, and several other speakers I tested showed an appropriate impedance. Looks like I can source a replacement from here for $50.

Event Electronics 1099 / KRK V8 *AM Tweeter Replacement Option* #50321 - Speaker Exchange

It seems when the sensitivity dial folded over, it shorted out, likely breaking contact somewhere. If I hold down on it to make contact, I can get the woofer to play, but only with a LOT of pressure. That said, if I flip the board over and look at the back, I can jump that dial (see pic) which activates the woofer and it plays fine. I haven’t be able to find a source for the replacement dial, and I don’t think this is something I could solder on myself. If I can’t source the dial nor find a comparable replacement (even if it means having to leave dial inside of cabinet), could I possibly just bypass the dial (like soldering the back to make a direct connection?) I’m guessing it’d just default to the +6db setting which we could at least match with the other speaker.

Here's a pic with a circle around the contacts I can jump to active the woofer.

The tweeter switch is also dead/shorted. Whenever you flip it, it creates a crazy popping noise, and I’m assuming this is what lead to the tweeter blowing. I can source this switch for about $15 (exact model), but again something I don’t think I can solder personally.



High pass switch
KRK SWTK00009 LF Switch for V88 V6 Series 2 and HF Switch for V8 Series 1 | Full Compass

The back gets hot, quick. I’m assuming it’s because of the short. Could it be a bad cap somewhere? I can’t find any bad caps. None look swollen or burnt.

What are my reasonable options here? I don’t want to buy the $50 tweeter until I’m sure the electronics won’t ruin it. If I can’t find a replacement dial for the sensitivity dial. Can I bypass it?  I’d be willing to buy a cheap tweeter to test it with.

At minimum, say we can’t really do much else, wondering if we could turn these into powered subs. If I could at least get the woofer working in the problematic one, could we disable the tweeter in the other and just have a pair of 8” subs? We were able to plug the good one into the subwoofer port of his receiver and get it to work as a sub, and it actually sounded pretty nice.


Manual
http://www.krksys.com/documents/V-series_V8manual.pdf

Schematic

http://www.krksys.com/documents/V-series_V-8SchematicRev-1.pdf