TC Electronic Studio Konnekt 48 revival

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

There are no pull up/down resistors on this clock signal, it's not like I2C. And yes, i did think about a buffer being useful, but the signal looked quite pristine on the scope, and it's "just" at the sampling frequency (44.1KHz up to 192KHz)

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Re-scoped the signal after reinstalling the line-out daughterboard - LRCK signal's as clean and as square as without it Score!!!

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Well, i "finally" swapped my Saffire out for the Konnekt last night, after the bodg... *ahem* repair, fiddled with the bass management, but... No sound out of my subwoofer, despite the meters in its control panel being active, and the sub being fine.

Today, took the case off again, and went straight for the clocks for the 8ch DAC that handles line outputs 5-12, and wouldn't you know it... MCLK and BCLK missing >_<

Resistance to ground for those signals, on the chip side, about 2.7 and 1.2 ohms, respectively. Scrape / cut / kapton / resistor-leg time again...

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Nothing a few bodge-wires can't fix...

Lowest / "bottom layer" one was the LRCK from last night; the other two are the MCLK and the BCLK

After this, i re-scoped ALL the clock signals going to ALL the converters - all fine, and what one would expect

[SteveNielsen]

Re: TC Electronic Studio Konnekt 48 revival

The "bodge-wires" look pretty good, much better than I can do.

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Tweezers, good light, plenty of flux, leaded solder and a half-decent iron with a proper tip

[SteveNielsen]

Re: TC Electronic Studio Konnekt 48 revival

I have and use all that, just not a steady enough hand. I get into trouble with too much heat as well. I'm still figuring out what temp is best for what job. Takes experience I know.

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Well, temperature's only one side of the issue

A few months ago i got myself an Ersa i-Con Nano (60w or 80w, can't recall). What i can say for sure is, it works way better set for 250-280C, than my chinese Hakko 936 ripoff set to 300-320C

Quality tips = a whooooole different story...

[SteveNielsen]

Re: TC Electronic Studio Konnekt 48 revival

I've got what I think are good set of tips, Hakko 900. My solder station is ok, a RS Pro-Line 70w (bought on sale for $50) and I calibrate it for different tips. I use home made liquid rosin flux (from high quality violin rosin), kester 60/40 rosin-core solder, and tips are in excellent condition. It really boils down to me needing more experience and practice with all of it. With a 2mm chisel tip I usually have to get it up to 360-370c for general soldering.

[dryo]

Re: TC Electronic Studio Konnekt 48 revival

Hi all, i see there are specialists of the SK48 here! Would you accept to help me with my dead interface? It does not boot :-(
The main power supply seems to works fine (+14v, -14v, +7v OK) but i noticed a problem on the 3,3v: it shows 1,6v (but sometimes increases slowly few minutes after powering the board, up to 3,2v but no boot).
1,8v is provided using the 3,3v via a 1117-18 regulator (witch works well, tested)
I tested the board using external 3,3v power supply (800mAh required) and it started correctly and i could connect it to my computer without toubles.
I looked carefully at the motherboard and the shematics, but i am not able to find how is this 3,3v provided? I found no 3,3v regulator.
Thanks!

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

The 3.3v rail comes straight out of one of the transformers, it's the regulated rail (where the feedback is taken from).

A few months after reviving this one, i grabbed another faulty one off ebay, and the exact and only issue it had was a crapped-out main filter cap, precisely on the 3.3v rail. Stuck a 1000u/6.3v Rubycon YXG in there, and she started right up

You'll want to look on page 20 in the service manual, right at the top edge - it's VERY likely C489 kicked the bucket (crappy Hitano :puke: ).

[dryo]

Re: TC Electronic Studio Konnekt 48 revival

I changed both C489 and C488, and it works!! Thank you very much Khron!! Now i feel a bit stupid, it was easy...^^
I will now have to check all I/O sound but it should work :-)
I have a second SK48 that not boot, but all voltages are OK, spent a lot of time on it and my opinion is that the main DICE chip is dead...

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Assuming you have access to an oscilloscope, it might be worth probing the clock signal lines, starting with the 24.576MHz crystal next to the Firewire chip. Then move on to the I2S clocks (easiest to probe on the various ADC's and DAC's).

Does "no boot" mean the front panel LED animation doesn't even play?

[dryo]

Re: TC Electronic Studio Konnekt 48 revival

I have a UT81B digital scope/multimeter, it is limited to 10Mhz, but i will try to check the crystal anyway.
Yes, "no boot" does means no LED animation on front panel at startup. Only the blue ring around power switch. (no led on motherbord as well)
Repairing theses SK48 was a bit a challenge for me as it is a bit beyond my skills, but it helps me to improve ;-)
Thank you again for your assistance, it is great to share your knowmedge!

[dryo]

Re: TC Electronic Studio Konnekt 48 revival

Today i had time to spend on my second faulty SK48.
I checked the 3,3v rail again, but this time i set my multimeter before starting the board.
And guess what?^^ 1,7v during the first few second, then 3,29v!
I changed C489 and C488 and here we go, "TC" logo
I guess the 3,3v was too long to come and it prevented the board from booting normally. Or maybe the faulty capacitors were draining too much current to the GND.
It was quite vicious because only few seconds after powering the board the 3,3v rail was looking good...
I cant believe this fu...ing caps were faulty on this second SK48 as well. They had no visual marks of swelling, they just looked as new!
Everything works great now, i am sooo happy!
THANKS A LOT!

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

Oh, that's great to hear then Congrats on this one too

[solozabal]

Re: TC Electronic Studio Konnekt 48 revival

Finally I found someone on internet with same problem... My SK48 don't won't to boot up, no TC logo, and no fw connection.
I had problems with TC from the start when I bought it, for example, problem with first time booting, but it would always boot correctly after second boot, so I did not bother...

Current status is that it won't boot properly, maybe after 10-15 tries, than after 20min it lose fw connection.
So I decided to opened it and found out that this guy C489 is hot like hell... so I put another one 1000u 10V from some old MB.

Turn on, nothing..., than second time, it boot up with TC logo, connect to fw but for not long.. it loses connection after few seconds. So current situation;
power supply is ok I suppose?! +14V -14.5V +8.5V and +2.6V, and when it's turned off everything is same just no voltage on green wire (+2.6V).

Any ideas what will be my next step, maybe C488, I don't know..

[solozabal]

Re: TC Electronic Studio Konnekt 48 revival

..tested voltage on C489 and C488, it's 2,7v, needs to be 3,3.. is that problem or Im just focusing on wrong thing?

Q1 with heat sink on power supply board near 220V input is so hot, I can't even touch it, is this normal?

What bother me most is that when it boots up properly (1:30 times) it WORKS, and than after half an hour of playing music lose FW connection without any reason...

[dryo]

Re: TC Electronic Studio Konnekt 48 revival

You are right, you should get 3,3V here. Replace both C488 and C489.
Concerning Q1 on the psu i can't tell you, i never paid attention to it's temperature...

[Khron]

Re: TC Electronic Studio Konnekt 48 revival

The whole unit works quite warm (if not even hot), under normal circumstances.

But yes, if you're getting anything less than around 3.2v on the 3.3v rail, THAT is where you should focus your attention. That supplies ALL the digital chips, so if that's not right, "of course" it won't boot or anything

PS: In switchmode power supplies, NOT any random caps will work - especially some unknown ones from old mainboards. HINT: look at the photos on the main www.badcaps.net page Yep, you guessed it, old mainboards...

EDIT: On second thought, i just checked, and the green wire is "just" the "power good" from the mains-powered power supply. It's a bit low, but... Well, as a first step, just make sure the "main" 3.3v rail (which is on the SECONDARY of transformer TR5) is ok. You should be able to easily measure that on pin 1 of IC46 (optocoupler, square pad, white dot next to it), right next to TR5.

PS2: You do *** NOT *** wanna go around touching stuff on the MAINS side of the power supply. You should count yourself lucky that (i think) they went with an isolated-package MOSFET there. Otherwise, your temperature finger-probing would've provided you with a real nasty surprise