[klnglim]

Oh, right!

Not sure how that circuit works on switch on. There is a diode near the fuses in that area, I don't know if you've checked that. Anyway good luck!!

The Diodes u mention about show 0.245 V under diodes read in DMM, this one seem like unnormal?
I also just found one of the bridge rectifier has an issue so as j fet n channel

 

[baronbeehive]

The Diodes u mention about show 0.245 V under diodes read in DMM, this one seem like unnormal?
I also just found one of the bridge rectifier has an issue so as j fet n channel

Yes, that sounds off, it's a 100v diode, same as the others.

 

[klnglim]

Yes, that sounds off, it's a 100v diode, same as the others.

There is something I dont understand, when i took off those diodes from PCB, the DMM reading normal and no error, then I put it back, the DMM show 0.245V, that makes me confuse?
Do you know why ?

 

[klnglim]

There is something I dont understand, when i took off those zener diodes from PCB, the DMM reading normal and no error, then I put it back and checked again, the diode near fuse DMM show 0.245V, right side UV meter diode show 0.15V, both diodees become no polarity, that makes me confuse?
Do you know why ?

 

[baronbeehive]

There is something I dont understand, when i took off those diodes from PCB, the DMM reading normal and no error, then I put it back, the DMM show 0.245V, that makes me confuse?
Do you know why ?

I don't know, I hope somebody here can help with that.

Just to recap to before you had your latest problem:

1 - Your amp was working fine after your mods then...
2 - After a while the burning to the 2k2 resistor started again - did you do anything before this happened, I think you changed the layout. Also you found a broken wire at the back
3 - Since then you had more burning and have then replaced the transistors and diodes and fixed the carbonization issue and your traces are back to normal.

Is all that true?

You seem to be saying that all the connections and wires are good, but there must be something wrong, it is easy to miss something. Are you sure you have fixed the grounding issue, I feel something like this is still affecting your amp, you could begin by checking the output XLR's to see if anything at that end of the amp is grounded that shouldn't be.

Also check the traces going to and from the 2k2 resistor to see what could be causing the burning.

It's difficult to advise because we don't know exactly what's been happening.

 

[baronbeehive]

Might be a problem here?

 

[bloodhawk]

So stuff happened, my friend spilled beer on his amp xD
Tripped breaker and a full disassembly later, he ended up buying my amp minus my parts and we ended up salvaging most of the high end upgrades from his board and i installed those on my board. All in all after about 8 hours of work and a bunch of cash in my pocket later, i bought another MK VI+ from the HeadFi market for $722

Another 8 hours later and this is the result - https://imgur.com/gallery/hO0rZ9X

Now this kinda threw a wrench into my plans of adding the CCS tail and bias switch . But was a blessing in disguise as i was thinking about things, and realized that i like use 2 x 6AS7G's / 6080's along wtih 2 x 5998/7236's most of the time. Here is a question for @baronbeehive @SonicTrance @Maxx134 , how bad of an idea is it to have individual switches for each of the power tubes? I can easily tuck 2 switches to the far left end (left tubes) , next to the power button with drilled holes out front and the other 2 for the right side tubes on the far right next to the headphone jack. Making them super symmetrical and might actually look cool.
This will give me the freedom of choosing which sockets i plug the 5998's/7236's in.

 

[baronbeehive]

So stuff happened, my friend spilled beer on his amp xD

Careless!!

Now this kinda threw a wrench into my plans of adding the CCS tail and bias switch . But was a blessing in disguise as i was thinking about things, and realized that i like use 2 x 6AS7G's / 6080's along wtih 2 x 5998/7236's most of the time. Here is a question for @baronbeehive @SonicTrance @Maxx134 , how bad of an idea is it to have individual switches for each of the power tubes? I can easily tuck 2 switches to the far left end (left tubes) , next to the power button with drilled holes out front and the other 2 for the right side tubes on the far right next to the headphone jack. Making them super symmetrical and might actually look cool.
This will give me the freedom of choosing which sockets i plug the 5998's/7236's in.

Goddamit, bloodhawk, you like your music LOUD!

I'm not sure of the fine detail of the circuitry so you will have to wait to see what Sonic says but I don't think you could do that. ATM the tube mix is on uniform power from the amp and the different tubes make the best of it, but if you change each tube's power requirement that will feed back into the circuit giving effectively 2 different power requirements in the same circuit which I don't think would work.

 

[SonicTrance]

how bad of an idea is it to have individual switches for each of the power tubes?

If you think that mixing tubes sounds better than running same tube types its not a bad idea. Nothing bad is going to happen. I think its unnecessary with four switches though. Why not settle for one / channel?

 

[baronbeehive]

Nothing bad is going to happen.

Of course, the 5998 setting just doubles the current to the tubes but doesn't affect the circuitry thereafter.

 

[klnglim]

Might be a problem here?

Make me no choice so I have to take out the board and check all the broken traces, take off all the burning area components, clean out with alcohol, put some flux then refill the eyelets every single hole.
It needs some times to finish all the process, I also repaint the front display as dislike the Little Dot logo.

 

[klnglim]

Make me no choice so I have to take out the board and check all the broken traces, take off all the burning area components, clean out with alcohol, put some flux then refill the eyelets every single hole.
It needs some times to finish all the process, I also repaint the front display as dislike the Little Dot logo.

 

[baronbeehive]

Make me no choice so I have to take out the board and check all the broken traces, take off all the burning area components, clean out with alcohol, put some flux then refill the eyelets every single hole.
It needs some times to finish all the process, I also repaint the front display as dislike the Little Dot logo.

Yes, I can clearly see your problem now with your close ups!


Looks like your PC has been in the wars LOL.

Don't worry I don't know anyone here who hasn't lifted a pad or two. I was in your situation but I decided to get an engineer to check my mods before switching it on because I wasn't confident. Lucky for me he fixed all dodgy areas before sending it back.

Got to hand it to you for sticking at it. Good luck, those eyelets should help you to do a professional job which I'm sure you will. Keep us informed of progress.

 

[bloodhawk]

Goddamit, bloodhawk, you like your music LOUD!

I'm not sure of the fine detail of the circuitry so you will have to wait to see what Sonic says but I don't think you could do that. ATM the tube mix is on uniform power from the amp and the different tubes make the best of it, but if you change each tube's power requirement that will feed back into the circuit giving effectively 2 different power requirements in the same circuit which I don't think would work.

LOL That 0 dB is because the DX7s is in DAC mode. And my Music players are all set to 50% volume with windows being set to 75%.

But yeah really careless on his part. There is a reason why i never let people drink around my electronics or even let anyone into the room if there is a party at my place.

If you think that mixing tubes sounds better than running same tube types its not a bad idea. Nothing bad is going to happen. I think its unnecessary with four switches though. Why not settle for one / channel?

Wanted to do 4 just for the freedom of tube positioning. Because for example, this order of tubes - 6AS7G/5998/6AS7G/5998 does not sound as good as 5998/6AS7G/5998/6AS7G. Same with the 7236's.

Yes, I can clearly see your problem now with your close ups!


Looks like your PC has been in the wars LOL.

Don't worry I don't know anyone here who hasn't lifted a pad or two. I was in your situation but I decided to get an engineer to check my mods before switching it on because I wasn't confident. Lucky for me he fixed all dodgy areas before sending it back.

Got to hand it to you for sticking at it. Good luck, those eyelets should help you to do a professional job which I'm sure you will. Keep us informed of progress.

Yeap definitely lifted pads. The black boards actually have suuper stury traces and via, this older board has much more brittle traces. I lifted 2 pads even after being super careful.

@klnglim if the traces are super messed up, then i would definitely run 20 AWG solid core wire from one side of the board to the other, to make sure the continuity is perfect. This might be a little bit overkill. But it will ensure a perfect connection.

 

[Maxx134]

how bad of an idea is it to have individual switches for each of the power tubes?

Use four double throw switches.
Each switch to switch bias setting for each tube.

Then you will have ultimate freedom of mixing tubes in amp.

Just make sure your in correct switched position...

Double check switch with Sonic as we went over looking for high current switches in past.

I believe the switches should also be double throw, if you are only changing the cathode resisitor (bias mod).
I forget as I have an MK8 and did not need this bias mod.

I only adjusted bias for one tube type.

Wow that's a big project now.
Will be a big sense of accomplishment once done.