D'lator DVD conversion

[angelodp]

Hi Martin, Tom turned me on to JB Weld. I backed the inside with some thin metal and super glued it. I roughed up the inside areas so it would bite. I then filled in the original cutouts with the weld stuff and sanded, then bored the holes. That JB Weld stuff is rock hard and sticks.

This unit works very well but my voltage readings are ??

Current work & My first Dlator

PT HV ( VAC ) 119 --- 120
PT HV secondary ( VAC ) 135 --- 135
PT filament winding ( VAC ) 3.2 --- 3.2

after doubler ( before 15k dropping resistor ) 365VDC --- 360
Node 1 ( after 15k dropping resistor ) 344VDC ---- 333
Node 2 ( after 100k dropping resistor ) 317VDC ---- 247

Cathode of driver stage ( pin 3 ) 243VDC ---- 24
Plate of Recovery stage ( pin 6 ) 230 VDC ---- 230
Cathode of recovery stage ( pin 8 ) 1.4 VDC ---- 1.5

It would seem that my dropping resistors are the problem on current build?

*Note - error in this layout - swap 1M & 27k - see below for correct layout.

[IMG:619:990]http://i260.photobucket.com/albums/ii9/ ... omcopy.jpg[/img]

[martin manning]

Pin 3 is obviously out of step, and the CF driver stage is not drawing much current. Only 0.27mA is flowing through the 100K dropper; should be ~4x that. What are the grid voltages (pins 2 and 7)? Do you have the right values for the CF's bias resistor (1.8K) and load resistor (27K) installed?

MPM

[angelodp]

Pin 3 is obviously out of step, and the CF driver stage is not drawing much current. Only 0.27mA is flowing through the 100K dropper; should be ~4x that. What are the grid voltages (pins 2 and 7)? Do you have the right values for the CF's bias resistor (1.8K) and load resistor (27K) installed?

MPM

Yes 1.8k CF is verified & 27k correct

pin 2 204VDC

PIN 7 - nothing ?? 0

[Structo]

Might seem a simple question but have you tried another tube?

[martin manning]

Zero volts on 7 is good. Your layout shows the 27K and the 1M swapped. That would do it, I think.

[Structo]

Yep

[angelodp]

Martin, yes I screwed up.... I'll swap and re-test.

Thanks eagle eyes

A

[angelodp]

readings with swap

PT HV ( VAC ) 120
PT HV secondary ( VAC ) 135
PT filament winding ( VAC ) 3.2

after doubler ( before 15k dropping resistor ) 365VDC
Node 1 ( after 15k dropping resistor ) 334VDC
Node 2 ( after 100k dropping resistor )248VDC

Cathode of driver stage ( pin 3 ) 24VDC
Plate of Recovery stage ( pin 6 ) 223VDC
Cathode of recovery stage ( pin 8 ) 1.4VDC
PIN 7 - 0 volts

What should pin 7&8 be

[martin manning]

Pin 7 should be zero, 1.4V on 8 looks like a pretty good bias point to me.

...so how's it sound now?

[angelodp]

I had better post a revised and corrected layout for this. Then go play it.

Thanks Martin and Tom much appreciated.

ange

Just cranked it up and its quite good, very 3D. Very lo hum at high volumes.
I have a new EH-12ax7 in there. I also used a 390pf in place of the 1000pf that the schematic calls for.

This particular dimension enclosure offers just the right amount of room for a small build, wish I could find these enclosures in the market place. This one was made as a DVD burner in Israel. The front panel comes off with 5 screws and the top slides on for a neat finish.


[IMG1080]http://i260.photobucket.com/albums/ii9/ ... ctcopy.jpg[/img]
[IMG:987:1220]http://i260.photobucket.com/albums/ii9/ ... alshot.jpg[/img]

[angelodp]

Thanks to Martin and Tom for helping me workout the bypass on the Dlator, works great.
[IMG:576:559]http://i260.photobucket.com/albums/ii9/ ... -small.jpg[/img]
[IMG687]http://i260.photobucket.com/albums/ii9/ ... pass-1.jpg[/img]
[IMG548]http://i260.photobucket.com/albums/ii9/ ... 2-rear.jpg[/img]img]

[Structo]

I see you did ground the unused switch terminal.

Did you try it without that?

[angelodp]

Hi Tom, no I did not. Its quiet as a mouse right now. Is there a problem with that leg being grounded? Seems to work fine.

a

[Structo]

No it puts the grid of the first stage to ground turning it off in a sense.
On the schematic that Claus drew that lug is not connected to anything.
I thought it would be better grounded so that is the way I drew my layout.