The Rude Tube Build / Support Thread (MAJ + PSU)

[bernbrue]

You're not alone... I finished the unit but it doesn't work yet ;(

So, what is wrong? It can´t be a big issue.
regards
Bernd

 

[baadc0de]

Regarding the power transformer, I'm a bit confused... the PCB has different number of inputs for various voltages than what I was expecting.

I'm about to order a transformer, I see for the 250V volt input that there are two 3 inputs, one of which goes to the ground plane. Then the 9V input and the 24V input both have only two connections..

So, should it be.. 250V CT and 24V no CT, 9V no CT?

Also, how is CT usually specified, is it two taps of 0-125 or two taps of 0-125, where one is inverted phase? Sorry, I'm very confused

 

[RATMNL]

I used this one

http://www.musikding.de/Passive-parts/Transformers/Toroidal-transfomer/Toroidal-transformer-230V-250V-9V-24V::1361.html

Though I am a bit confused, cause I am used to that secondaries have different colours in each pair, but this one has: 230V/0.1A: Brown x2, 24V/0.5A Green x2, 9V/2.5A Red. Shouldn't these be positive and negative and if so, how do I find out...

Mark

 

[bernbrue]

Mark,
I used the same transformer. Since we have AC coming from the transformers secondary there is no polarity. So 230V for B+, 9V for heater and 24V for thé relays. For reasons of safety have a close look to the picture attached!
regards
Bernd

 

[RATMNL]

Aaah. It's AC. That makes sense.
Sooo.. hooking up the primaries in series a plus to a minus to get 230V on the primaries, and then just wire...
I always read the data sheet, but this one comes from some german company which websites do not have data sheets, so a bit stuck, butr your explanation does it, as well as the pictures, (which I'm saving into my reference guide folder)

Thanks! now I don't have to drag it to the electronics shop in a couple of minutes... Thing is a bit chunky

M.

 

[bernbrue]

I'm about to order a transformer, I see for the 250V volt input that there are two 3 inputs, one of which goes to the ground plane. Then the 9V input and the 24V input both have only two connections..

Don´t use the middle pin of the 3pin connector for 250V. You must use pin1 and 3 for the high voltage. You don´t need a 250V centertapped secondary. I still don´t have any pcbs.
regards
Bernd

 

[RATMNL]

No I won't. pin 2 = Ground....
though I do have the CU-folienschirm gelb/grun wire, should I connect that to my star-ground, or could that be connected to that ground pin 2?

(thank god I understand German..)

EDIT: oops weren't talking to me

 

[baadc0de]

I'm about to order a transformer, I see for the 250V volt input that there are two 3 inputs, one of which goes to the ground plane. Then the 9V input and the 24V input both have only two connections..

Don´t use the middle pin of the 3pin connector for 250V. You must use pin1 and 3 for the high voltage. You don´t need a 250V centertapped secondary. I still don´t have any pcbs.
regards
Bernd

Makes sense now, thanks!

 

[bernbrue]

Before powering up a new built I always do a check for shorts. I take the multimeter and test if there is some kind of resistance between the inputs poles (PSU and mainboard).
regards
Bernd

 

[bernbrue]

CU-folienschirm gelb/grun wire, should I connect that to my star-ground, or could that be connected to that ground pin 2?

(thank god I understand German..)

EDIT: oops weren't talking to me

Connect it to star ground.
regards
Bernd

 

[JayDubrek]

Anyone completed this yet?
Cheers
Jay

 

[RATMNL]

DOn't think So...
Jandoste had wired it up, but his one didn't work (why is still unclear to me).
I have the PCB's Populated and are about to order the Edcor's, which are the last parts I need.
(excpet for a front panel and where the Hell do I tap power for a power lamp? and which lamp to use, haven't worked on the machine, and this is still unclear to me: It's a pretty dumbed-down question but I don't want to ruin it. My electronics experience has been so project-based that I know a lot about the things I've been working with, but kind of skipped the "basics", got to read a book!)

Mark

 

[bernbrue]

Where is Jerome?
regards
Bernd

 

[JayDubrek]

Didn't think so... waiting till January to order my Edcors then putting this together.
For power I just normally run a 240VAC mains indicator lamp after the power switch across the supply or 6.3v lamp across the heater supply- been a while since looking over the schematic but seems worthwhile checking over thoroughly against the PCB...

 

[baadc0de]

I've built mine, and it somewhat works, but I'm getting severely highpassed signal. Oh well, off to troubleshooting. Btw, the build manual is ... well it could be much better

here's the rundown:
-- I get distortion yay
-- I also get a looot of noise (not so yay) which seems to be at the input or distortion section, turning the output down makes the noise go away..
-- first two functions work, other functions are no signal
-- whole response looks like a low shelf, ~20dB, starting at 6.4Khz and goes flat at about 400Hz
-- engaging LPF kills most of the signal
-- my output knob is wired around (but it's wired like in the manual)
-- one one channel, heater comes to V2 socket pins but the tube doesn't glow. Swapping the tubes reveals that the tube will glow in the other channel. Bad socket? Other ideas?

questions:
-- what about PAD and SQUISH? I assume those can safely be let unpopulated
-- I have Carnhill VTB9071 on inputs, series wired primaries and secondaries for 10k:10k
-- I have Carnhill VTB2380 on outputs, series wired primaries and secondaries, which if I bought to be http://www.audiomaintenance.com/acatalog/CA-18-VTB2380_extended_info.html 15K:600. Colin said it is the same format electrically and physically as VTB1847, so I wired it in->yellow,brown, out->blue,violet and joining orange+red and green+black.

But looking at it, it "might" be that the idea is to use it inverted, so that the blue+violet is primary... we'll see.

 

[bernbrue]

Hi,
make shure that you bridge the two contacts for the squish switch. C7 (C9 in the schematic) must have contact to ground. Your noise issues is most likely caused by a wrong wiring of the overdrive switch. There are a few junctions (wire bridges) on the pcb for the heater. It seems that you forgot the one or the other. The function switch seem to be wired wrong as well. . The cap for the LPF is too big, choose another values according to your preference. I suppose that the transformer wiring/Di jacket wiring is wrong as well. I still haven´t got any pcb from Drask and I haven´t heard from him for longer time now. Neither do I feel responsible to troubleshoot his pcb nor to update his "manual".
regards
Bernd

 

[bernbrue]

-- first two functions work, other functions are no signal

You forgot to bridge the pin 2-6 on the Lorlin switch (SWa). I advise you to print out the schematic of my prototype, then it gets clear.
regards
Bernd

 

[baadc0de]

The way overdrive is written in the "manual" it will put ov-2 and ov-3 in parallel instead of just choosing ov-3, I'll fix that but it should be the same in ov-1 and ov-2 mode. The drive knob seems to make little or no difference. Also, regarding heater, all the jumpers are there and the juice does get to the pins below the tube socket, but not to the tube, so that's why I think it's mechanical failure of the socket. Too bad, those are a b*tch to desolder!

Ok, I'll link the 2..6 functions on SWA, I have found another schematic "CVfinal_tuning.jpg" which I didn't have before that shows more info like that clearly. Bridging "squish" makes mode #2 oscillate. I will check resistor values again and compare with the CVfinal schematic. The drive knob is having little to no effect for some reason, it must be wired wrong (1..3 = 1..2 or something). The build manual says to just connect 1 and 2 to ther PCB, but I see that in the schemo, it's wired with all 3 pins. Crud.

Bernd, thanks for helping and yes I understand that it's not your PCB and you don't need to, but thanks anyway!

 

[bernbrue]

Hi,
do the following test routine:

- insert a not too hot line signal (synth demo song or whatever) into the DI jacket of the RT.
- take an unbalanced  jack cable and connect it to your line mixer, put down the gain setting on the mixer to minimum
- at the other end of the jack cable connect a test prod or a crocodile clip to the tip of the jack
- test the signal at the spots, marked in the schematic
- settings: function to triode, bias about 0,4 mA, overdrive switch to "Normal", drive pot at about 10 o´clock, output pot at 8 o´clock

test point 1: there should be a hot but undistorted signal
test point 2: there should be a slightly less hot undistorted signal
test point 3: there should be a signal with significant less level
test point 4: there should be a signal that can be turned up and down with the drive pot
test point 5: there should be a signal that can be influenced by the Drive pot and the bias pot (concerning level and distortion). When turning the bias pot  the meter should move from 0-1mA

With this test you can at least isolate the problem. Report back your results. After that we are going to measure some voltages. Good luck!
regards
Bernd

 

[baadc0de]

Flipping the PCB reveals one culprit .. The "manual" wants you to wire the drive pot as a variable resistor between ground and input to 6as6, neglecting the output from the EF86 section entirely for some reason.. this takes care of both noise and low end. However, the drive and output controls are a bit "ineffective". I was expecting the drive control to be able to completely "cut off" the signal. So there could be some more culprits

EDIT: one of the drive pot pins was coldsoldered... resoldered it and hardwired overdrive to its lowest setting and now we're "kind of" in business, there is way too much distortion, will probe to see where it develops. Could it be that the output section distorts of a 15K:600 OT was wired vice versa?