TC Electronic Studio Konnekt 48 revival

[jlascotty]

Re: TC Electronic Studio Konnekt 48 revival

Neither are visibly bloated - new ones should be (fingers crossed) arriving in the post tomorrow. I'll update people once I've done the change. Always good to show people there is hope! I hardly ever use the XLR/Jack inputs on the front, but I recall that CH1-2s pre-amps/gain seems to be much lower than 3-4, so I may as well try to fix those while I have the unit open. Any quick suggestions on how to fix those will also be more than welcome

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Is that on the XLR inputs 1-4, the jack inputs 1-4, or both sets? Might be worth double-checking, to narrow down the possibilities.

One other thing to consider would be to trace the signal, ideally with an oscilloscope if possible. Or if you're really determined, you could even use one of the line inputs on the back of the SK48 itself for that - cobbling together a probe might be a tad more "interesting", though.

[jlascotty]

Re: TC Electronic Studio Konnekt 48 revival

Not too sure when I'll have time to check everything on the inputs, but I've managed to fix the power cycle issue.

Changing the caps on C488 and C489 has fixed the issue! Thanks!

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Glad to hear that

[jlascotty]

Re: TC Electronic Studio Konnekt 48 revival

I did a quick plugin test to see what is working on the combo inputs.

Mic XLR input + Mic XLR input with phantom power is working fine on all 4 inputs.

I am however having an issue with CH1 + 2 instrument jack level. 3+4 are ok.

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Ok, at least we've narrowed down things. Can't be the ADC's or the preamp chips, if the mic inputs on the "bad" channels are ok (since they go through the same chips).

All that's left is to check the circuitry associated with the jack inputs on CH1/2 (an opamp each plus some passives) - page 13 of the schematics, top "half" of each channel.

So the issue is "only" lower (than expected) gain on those two jack inputs?

[jlascotty]

Re: TC Electronic Studio Konnekt 48 revival

Actually, I've done another test and it's an issue across the mic inputs as well now Wondering if it's not a consistent issue now.

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

And the same input signal is quieter on inputs 1 & 2, than on 3 & 4?

Do you happen to have access to an oscilloscope? Or, worst case, i suppose you could use another input on the K48 itself, to do some signal tracing...

[jlascotty]

Re: TC Electronic Studio Konnekt 48 revival

No access to an oscilloscope just yet. I was thinking about buying a cheap one for odd projects like this.

It's definitely just an issue with CH 1&2. I'd even say CH1 is a little bit lower than 2.

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Well, like i said, in a pinch, you could even use the K48 to probe around for signals.

Might i suggest going for an old-school CRT-based scope, though?
https://www.youtube.com/watch?v=Xh9FNRpta9s

[petehall347]

Re: TC Electronic Studio Konnekt 48 revival

you can build a simple signal tracer if you like to .. something like a .01uf capacitor . not hard and fast as to value but better being low its just to block DC from entering the input of your audio amplifier that you would use as a listening device . i am not going to explain how to wire it up . that depends on what you have laying around .

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Well, the instrument inputs 3/4 already have DC-blocking caps (as do all the other analog inputs anyway), and it's high-impedance, so shouldn't (excessively) disturb whatever circuitry's being probed

[petehall347]

Re: TC Electronic Studio Konnekt 48 revival

as you were .

[jlascotty]

Re: TC Electronic Studio Konnekt 48 revival

Thanks Chaps, going to take another look at it, in about 2 weeks when I've got some spare time

[mamm7215]

Re: TC Electronic Studio Konnekt 48 revival

Sorry to dredge up a dead thread but I just wanted to revive it to say a big THANK YOU to Khron and everyone here. My Konnekt48 died with the blue power light and I'd already had it repaired before for the same kind of issue. I replaced C488 and C489 as per this thread and it lives again! Full function too. Anyways, thanks guys. You rock!

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

No sweat, glad to hear one more unit got saved from the landfill

Mine's been starting to act up when starting up from cold though. I had to replace C489 some time ago (again). It takes a few minutes for things to warm up enough for it to progress past the "hiccup" stage, so i'm guessing that's the problem again. Fortunately that's only an issue when i get back from a weekend away, and that hasn't yet warranted the hassle of opening the thing up once more (dozens of screws and jack nuts and all that)...

Maybe someday i'll get around to it

[mamm7215]

Re: TC Electronic Studio Konnekt 48 revival

Yeah, like I said I had mine fixed a few years back for the same thing. This time I also noticed it would take longer and longer to post the startup screen. I suspected bad caps but didn't know where to begin looking. Again, thanks for this thread. When I opened it up they'd already done C489 but put in a 10V cap (although smaller than the original at C488). Oddly enough they'd also replaced C486 and C487 which tie into the 48V circuit so maybe that was the issue with the dying pres these things were known for years ago. In any case some Panasonic FMs 470u 35v went into 488 and 489 and all good. There's better converters nowdays but the Konnekt48 feature set and performance imho made this probably the best interface for the dollar and then some, hands down.

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

I don't know if the phantom power killed any pres - i've heard issues about the gain potentiometers going bad in some (early?) revisions of the entire Konnekt lineup. Mine's never had an issue with those, and neither did a Konnekt 8 i have (which i also got used, but i haven't even turned that on in years).

I still use mine standalone as a volume & speaker controller, and subwoofer crossover

[mamm7215]

Re: TC Electronic Studio Konnekt 48 revival

I don't know if the phantom power killed any pres - i've heard issues about the gain potentiometers going bad in some (early?) revisions of the entire Konnekt lineup. Mine's never had an issue with those, and neither did a Konnekt 8 i have (which i also got used, but i haven't even turned that on in years).

I still use mine standalone as a volume & speaker controller, and subwoofer crossover

Yeah, not sure why they'd replace those but they've clearly been replaced.

[solozabal]

Re: TC Electronic Studio Konnekt 48 revival

Hello everyone,
this is my second attempt to repair Konnekt 48. For several years now, the sound card has been out of order because I didn't have time to dedicate to the repair. And now at the time of the corona-virus there was a little more free time so I decided to try to fix it again.

Since there is obviously a problem on my Konnekt 48 with the 3.3V rail, I tried using a power supply to insert that voltage after removing the L65 and L64, in between which the TR5 is located. The board pulled the maximum limited current from the power supply so that apparently something was shorted on that rail.
I tested all the capacitors in the first section before the 1.8V rail and everything is fine. The only thing that heats up on the whole board when 3.3V is on, is the Dice II chip which heats up in a very short time to a very high temperature. In addition, all capacitors near the chip are short-circuited when measured using a continuity test directly on the board.
Is there any other way to test Dice II before I declare him dead?