U67 Clone : D-U67 PSU problems....

[Lordward]

Sorry, i can't help you with that. I will have to investigate all the connections etc. and i really have no time currently.
With multipin cable, use multimeter beeper and check all pins for the shorts. One pin from one side and test all the pins from the other side, then another pin and exactly the same procedure.

Thanks for the tip, I had actually done that to begin with.  All is as should be.  I'll keep looking though.

 

[Lordward]

UPDATE:
I've had a bit of success now.  First of all I turned on the PSU and it made again another small stream of smoke but then stopped.  So I measured the thing.

I checked B+ and H- with resistors, 33ohm/2W(pin 3-4), 480kohm/0,6W (pin5-7), and I can get H- down to exactly - 6.33DC  but not any more.  B+ i can only get down to 225DC (should be 210).

I'm wondering if I need a transformer with less output?  Even though I'm using the one on the Mouser cart.....
I'll check if I get sound now...

 

[Lordward]

And final update:  After mailing with Dávid Fehér  from this forum he discovered that my mic was simply not drawing power. And I double and triple checked everything...again and again.  So, I thought, if the mic is not drawing any power than the tube won't light up.  And so was it of course.  8)

Long story short, I took out the tube and looked at the socket.  The gold grips that hold the tube pins looked relatively wide to me so I simply took a small screwdriver and bent them all in a bit more dense.  Lo and behold.....it worked and I got "normal" measurements.

Then I had to change, as suggested by Dávid, the 56K on the Plate trimmer to about 33K.  Then I could calibrate as expected.

Finally I did a sound check: Mic works, in Cardioid mode with low cut and –10db.  In Omni it’s very quiet, in Fig 8 I get nothing - no sound - at all.  More debugging to do.

One other odd thing I found is although it sounded pretty good in Cardioid mode I found it to sound better with -10db.  That's a first for me.  Must go hand in hand with the Omni and Fig 8 not working correctly..... :-X

 

[mrerdat]

Carefully go over your capsule/pattern/pad/hi-z connections again.  When I built my first 67 I experienced similar anomalies because I had neglected to solder the switch wire that connects to the same turret as the backplate wire and didn't realize it at first. 

 

[Lordward]

Carefully go over your capsule/pattern/pad/hi-z connections again.  When I built my first 67 I experienced similar anomalies because I had neglected to solder the switch wire that connects to the same turret as the backplate wire and didn't realize it at first.

Thanks, I'll do that!

Edit: I see that everything is wired as it should be.  I'll change front to back to see if there are any reverse issues.  Wouldn't be the first time I had issues with this brand of capsule.

 

[Spencerleehorton]

I can do a group buy of these transformers for £50 each for 30 units if anyone's interested?

Regards

Spence.

 

[TLRT]

I can do a group buy of these transformers for £50 each for 30 units if anyone's interested?

Regards

Spence.

Which transformer?

 

[Spencerleehorton]

sorry i meant the BV12, would be same specs but slightly different design, designed by best windings.

 

[TLRT]

sorry i meant the BV12, would be same specs but slightly different design, designed by best windings.

I have AMI BV12's to compare, it is really nailing the original very well(I'm using original neumann capsules too)
So I'd be interested!

 

[Spencerleehorton]

I have a capsule that was done by Eric and a sowter wound version to compare with so I'm interested in comparing the results as the sowter will be tested along side it as well.
And too be honest I've never really been happy with the sowter version, that's why I'm persuing this alternative.l