DRIP Ultra British Problem

[kmozart]

Hi,
I'm not  super tech savvy, but I've done bunch of DIY ( 1176, Piltecs, CApi,... ) projects successfully. 
As Drip lacks the documentation and the building instructions, I'm struggling with this project,

  I'm trying to finish my two boards of Drip ultra British Mic Press.
I got them all stuffed, turned on, no explosion, but the voltages are not correct.

I got 298V by the regulated B+ one side gf the R7 51K. On the other side is says 205V, but I got 294V. Also Where it shows 73V I got 293V!  Bt the R10, where board show 138V I'm  getting  297V!

Any Idea what to check? All the values of the resistors are correct in that area. I've got diodes 1N4007 installed in the dedicated place on this board, instead of the tube rectifier.

Thank You!

 

[scott2000]

No schematic to look at??? Nothing??

I'd guess make sure of the values again and make sure none are faulty....

Doesn't sound right at R7....

 

[kmozart]

Just triple-checked everything, all seem fine as of the parts value.

I got basic schematic for redd 47 from Google following it, all seems good...

 

[ruffrecords]

If you can post the schematic you are actually using which shows where are the various resistors you have quoted, that will help us a lot.

Cheers

Ian

 

[ruffrecords]

Often, if you get a lot of high voltages in a tube circuit where you expect much lower ones it may indicate one or more tubes is not working. Do they light up?

Cheers

Ian

 

[TheJames]

It actually sounds like you don't have any tubes installed, thus no load anywhere.  All the voltages will be high.

 

[kmozart]

SORRY!  Being slammed with sessions last couple of days...
Yes I have tubes installed,  and they are lit. Power tubes are warm when I touch them but audio tubes are lit, but they barely worm up.
Thanks for the schematic Scott2000!  How can I download it? I don't have that one.

 

[ruffrecords]

SORRY!  Being slammed with sessions last couple of days...
Yes I have tubes installed,  and they are lit. Power tubes are warm when I touch them but audio tubes are lit, but they barely worm up.
Thanks for the schematic Scott2000!  How can I download it? I don't have that one.

Right click - save as

CHeers

Ian

 

[kmozart]

OK,... Chrome di it!  Safari, not,...    ;D

 

[kmozart]

This the schematic I was looking at. Pencil values is what is the mark of the resistors on the drip board. red values circled is what the voltage  supossed to be, and the pencil values is what I'm getting.

 

[PRR]

R11 R20/R27 are not returned to zero V.

Likely a missing wire back to the power supply.

 

[kmozart]

R11 R20/R27 are not returned to zero V.

Likely a missing wire back to the power supply.

You mean  R11 and R20/27 with the pencil or the stamped ones?  the schematic does not correspond with the Drip board in the markings,...

 

[PRR]

> You mean  R11 and R20/27 with the pencil or the stamped ones? 

If you don't know, then I sure don't know.

But where you should have 3.7V on one end of a 200 Ohm resistor, and zero V on the other end, you say you have 290V!! And I bet the same as the other end. Your zero V is not zero V. Same as fixing trailer lights. Find the break in the circuit.

 

[kmozart]

Update:

As PRR suggested, one side the R12 (3.7V) was not having connection to the ground.
When I jumped R12 (3.7V) to the power ground, and lift the HEATER GND, (If you are familiar with DRIP ULTRA BRITISH Board) I got voltages little higher from where they supposed to be, but just about right.

3.7V = 3.55 (R12)
1.65V = 1.67V  (R4)
138V = 142.7V (JUMP)
73V = 74.9V  (R8)
205V = 207.7V (R7) 
290V regulated B+  =  290V (R7)
380V = 353.6V !!! (resistor A)

Also, with no microphone on the input, I got a huge ground noise. When I plug SM58 Microphone, hum goes way down, but still there.

Any Idea where is the mistake here?

Thank You!

Kostadin Kamcev

 

[kmozart]

This picture shows how I temporary jumped the resistor to the ground.

 

[kmozart]

And there is one more picture, where is shown HEATER GND Lift. .

 

[My3gger]

Hum can be further grounding problems, check if phantom has correct voltages and works propery before trying condenser mics.
A few people told about problems with OA2, mostly hum and also other stranger things. There is no reason not to change them to zener diodes, pcb is big enough for such a simple circuit.
Check pin 1 grounding, there is lots of reading if you google "pin 1 problem". Bill Whitlock is one of good authors.
I would print traces and draw the circuit so you can be sure nothing escapes you when troubleshoting.
Drip 47 type sounds good, it just has many unneeded components and connections, all of this rises cost. It can easily be done with simple p2p layout many of us posted, needs no fancy parts.

 

[johnheath]

Update:

As PRR suggested, one side the R12 (3.7V) was not having connection to the ground.
When I jumped R12 (3.7V) to the power ground, and lift the HEATER GND, (If you are familiar with DRIP ULTRA BRITISH Board) I got voltages little higher from where they supposed to be, but just about right.

3.7V = 3.55 (R12)
1.65V = 1.67V  (R4)
138V = 142.7V (JUMP)
73V = 74.9V  (R8)
205V = 207.7V (R7) 
290V regulated B+  =  290V (R7)
380V = 353.6V !!! (resistor A)

Also, with no microphone on the input, I got a huge ground noise. When I plug SM58 Microphone, hum goes way down, but still there.

Any Idea where is the mistake here?

Thank You!

Kostadin Kamcev

Those voltages seems just fine... expect +/- 10% from schematic

Best regards

/John

 

[adrian]

kmozart  did you find a solution to remove the hum? 
 

 

[Raja]

Hi,
I'm not super tech savvy, but I've done bunch of DIY ( 1176, Piltecs, CApi,... ) projects successfully.
As Drip lacks the documentation and the building instructions, I'm struggling with this project,

I'm trying to finish my two boards of Drip ultra British Mic Press.
I got them all stuffed, turned on, no explosion, but the voltages are not correct.

I got 298V by the regulated B+ one side gf the R7 51K. On the other side is says 205V, but I got 294V. Also Where it shows 73V I got 293V! Bt the R10, where board show 138V I'm getting 297V!

Any Idea what to check? All the values of the resistors are correct in that area. I've got diodes 1N4007 installed in the dedicated place on this board, instead of the tube rectifier.

Thank You!

Hi,

Sorry to bother. Do you have the Drip PDF for these PCBs? I have two of them the same as yours, but unfortunately, the "manual" is no longer available on the Drip website.

-Raja