D-EF47 Tribute To Oliver Archut U47 Build Thread.

[wimmy7986]

Shot with volt meter.

 

[trans4funks1]

Take a look at this:

http://groupdiy.com/index.php?topic=51308.msg652017#msg652017

 

[tubestation]

Hello,
Wimmy, are You living in a 230 or 115 Volt Mainvoltagecountry ?
If You have 230 ( or 115 ) Volt AC at the Primary  of Your Powertransformer and the Secondary reads 270 VAC  when 230 VAC  are rated for the Transformer, there Must be something  wrong with him. Could be shorted Windings on the Primaries or a wrong Windingpattern from the Factory. I would check the Tranny first, unconnected  from the Powersupply.
To meassure Voltages without a Load ( Tube or Replacementresistors )  don t shows You the Voltagedrop of Your RC Network because If no Current flows, no Voltagedrop. If You  " Activate " Your passive Powersupply without the Mic connected and than plug the Mic, the  Filamentwire of the Tube melts, the Tube is destroyed., because of the much too high  Heatervoltage You have without the Load of the Filamentwire . If You ever  activate  a passive  Powersupply without a Mic plugged, make sure all  Heater Capitors are discharged ! ! !  before You plug the Mic otherwise You may need a new Tube. I discharge Capitors with a Lightbulb  in a Socket with  isolated Cables  a 100 Ohm  5 Watt Seriesresistor and Crocodileclamps ( to Plus and Minus of the Capitor ) I don t know If the Capitors like this fast Discharge very much but it works and a few Seconds later the Capitor is discharged.. You can also use only a Bleederresistor ( I would say 500-1k Ohm but not sure, maybee Somebody could confirm, please ) from Plus to Ground to discharge  but I prefer  to  let  the Lightbulb  to " consume"  the  Charge. Just to Off the Powersupply and waiting won t help because a good Capitor can hold the Charge  ( the high Voltage that kills Your Heater ) for Hours .
Hope I didn t answer Questions Nobody asked.
Greatings
Lothar

 

[Spencerleehorton]

i had a similar problem once, i wired the transformer the wrong way round!!, maybe you've done the same?

looking at your picture your IEC doesnt look right!!!!! is that two wires coming off it and one going to the txf and one going to the pcb?
you should be putting the fuse on the live (brown) wire side i thought?
from your IEC there should only be blue(neutral) and brown(live) coming off to the txf, but obviously the brown(live) going to the fuse before then going to the txf.
i would unsolder and start again or put some more detailed photos of the IEC.

regards

Spence.

 

[wimmy7986]

Right now I have the primary wired in parallel for 120V.  Brown and grey going to the cold terminal of the IEC, and blue and purple going to one side of the switch.  That should be correct, right?  The other wire i think you are seeing is the wire to the primary of the other xformer. 

Also, with the secondary unhooked from the PCB, I'm still getting 270 VAC.  I think I'm just going to order a new one and report back.

Thanks so much for your help!

 

[Spencerleehorton]

Ah, I didn't realise you are on 110v, one other thing is normally I would use a DPDT switch, I think your using a SPST?
Are you testing the txf without it being plugged into the pcb? If not I would try this, try and keep it as simple as possible so it can only be the transformer at fault.
Sounds like you have it connected right but I can't see the wiring guide for it?

Spence.

 

[trans4funks1]

Thanks guys for the quick replies!!

I snapped some pics to show whats going on. 

When  comparing your photo to this data sheet: http://www.mouser.com/ds/2/410/VPT230-110-224265.pdf it appears that you have wired the secondary in series when it seems it should be in parallel just as you have connected the primary.

If the transformer secondary is wired in series it is specified in the data sheet to output 230 volts. It seems to makes sense that you are measuring 268+/-aAC as you have shown in the second picture.

Try wiring the secondary in parallel to see if that gets you in the proper range.

After you have done that try connecting a load, as suggested in the link I posted earlier today, to see how close you are you the operating voltage.

 

[trans4funks1]

...according to the diagram on pg 3...

The diagram on page 3 does not apply your project for one obvious reason and one other small detail.

The obvious detail is that the diagram is describing a primary connection to a 230vAC mains supply and a step down to 115vAC on the secondary.

The other small detail is that the color code for the transformer displays the primary and secondary in the opposite orientation from the products data sheet. In other words, the BLACK, ORANGE, RED and YELLOW wires shown on that diagram as the primaries are shown as secondaries on the data sheet. Swapping the orientation may or may not matter with a toroidial transformer. If I recall correctly, swapping primaries and secondaries in traditional E core transformers can lead to slightly more hum. In any event, it seems like it would be less confusing to follow the conventions described by the data sheet.

I hope this helps.

 

[wimmy7986]

Hey trans4funk1,

I think i'm a bit confused...  Doesn't the data sheet indicate that grey brown blue and violet are the primary side?  Thats what I have wired up now to my IEC and switch, and the data sheet indicates that is the primary side. 

When I wire the secondary in series, I only get 135 VAC.  I've got another transformer in mail, maybe this is just a case of a bad transformer.

 

[tonzauber]

[...] one other thing is normally I would use a DPDT switch, I think your using a SPST?

Hi Spence, wouldn't a DPST make more sense?

Best, Georg

 

[trans4funks1]

Hey trans4funk1,

I think i'm a bit confused...  Doesn't the data sheet indicate that grey brown blue and violet are the primary side?  Thats what I have wired up now to my IEC and switch, and the data sheet indicates that is the primary side. 

It was the diagram on page 3 that has the colors of the primaries and the secondaries swapped. Yes, your photo of your build looks like you are following the color code suggestion of the data sheet.

When I wire the secondary in series, I only get 135 VAC.  I've got another transformer in mail, maybe this is just a case of a bad transformer.

Maybe I am confused.

Your photo of your build shows that your secondary is wired up in series. The second photo shows that you are measuring 268vAC. That makes sense and agrees with the dadt sheet specs. The 230vAC output catalog spec for that transformer is assuming there is a load on the circuit which is pulling the voltage down... down to the 230vAC spec.

Have you tried wiring the secondary in parallel? I would expect you will see about 135vAC when you do. 135vAC seems like the proper output of an unloaded transformer in this circuit. The bridge rectifier will crank it up 1.4x to 190vDC and the filtering, the trimmer and the load should bring it back down to desired 105vDC B+.

 

[tonzauber]

Regarding the 230V on the rectifier input:

it is not a typo,
when designing tis one I had long Chat with Oliver , and regarding the power that is what I have been recommended for B+ in this setup ,  the EF800 configuration operates better with a nice upstream potential, like having a waterfall just before the river so it make the tube stable and quiet ,  so don't worry , I have one working here and do know that this is done for a reason ,
Hope this helps,
Best,
Dan,

 

[wimmy7986]

Hey Tans4funks1,

For a dummy load, I calculated a 12 Ohm 2 W resistor for the H+.  With the load, it brought the voltage down to around 5 or 6 volts DC, so it should be good there. 

For B+, i tried a 550k 1/4 W resistor which didn't change anything on the VAC input.  I also tried a 120k and that didn't change the VAC input either.  AND, I'm still getting about a 100VDC jump when I switch polarity patterns...  Is that just because there is no capsule in the circuit?

Thanks!

 

[trans4funks1]

Edit to explain: I wrote this before the last  reply was posted but I had trouble uploading it, so some of it may seem as if I didn't read the previous post.

Regarding the 230V on the rectifier input:

it is not a typo, ...
Best,
Dan,

Ah yes, now I  recall that Dany wrote about this previously.

I should back out and defer to Dany and I suggest you ask him again for clarification about this.

Never the less I think that wimmy's existing transformer is acting exactly as it should be expected to act. I didn't understand the context of the concern with trying to match the 220v note on Dany's schematic.

Having said that I just ran a simulation of the circuit shown on the schematic and without a load it appears to me that the voltage at R7, with the trimmer set at 8Kohm and without a load from the mic circuit, will be somewhere in the vicinity of 250vDC. I can't imagine the load of the mic pulling that down to 105vDC. Using a 150kOhm 1/2 watt load resistor will provide an idea of what plugging the mic will do to the B+.

I've been trying to be helpful, but now I regret adding to confusion when it seems that only Dany can confirm what we should expect to see in his circuit design.

Good luck.

 

[tubestation]

Hello,
Do You have also no DC Voltagedrop with the 150k Dummyload, installed ( from B+ to 0 Volt ) ? that would be strange.
The Relay inside the Mic just  switch the Reardiagramm. It only connects the Reardiagramm with the Frontdiagramm in Omni Mode. In Cardioid the Reardiagramm  Isn t in the Signal at all. The Capsule doesn t pull any Current. How can You have a 100 Volt Jump of B + when switching ?  It doesn t Matter for Your Voltages If the ( correctly operating ) Capsule is installed  or not. If You have any Short  or a  bad Isolation inside the Capsule , If Current flows to 0 Volt than You can have a  big Voltage Jump. ( Drop ) .
When does it happen ? In Ommni or in Cardioid Mode ? I am pretty sure You find the Problem in the Powersupply. Maybee a wiring Error or  a cut or shorted Trace, Maybee in the Relayswitching Part,? because You obviously have a Problem  when switching .
Like Trans 4 Funk suggested use a 150k Dummyload  for B+ and Your calculated 12 Ohm for  H + and check Everything  for Isolation and Continuty before You plug the Mic. I hope You didn t blow  more than 80 Volts to  the Capsule. If so , maybee the Diaphgram got sucked into the Backplate . Do You have a cheap Spearcapsule for Your Testings?  ( after beeing 100% sure that Your Powersupply works like it should )
Good Luck,
Lothar

 

[wimmy7986]

So i did some more testing tonight with the dummy load, and feel good about my H+.  The B+, however, is a complete mess.

In Cardoid, with a dummy load, i get 70VDC.  In Omni, with a dummy load, it climbs up to about 170VDC (until i turn it off, it just keeps rising.)  I've checked and rechecked everything to make sure there is no solder bridging or shorts.  Could it be my switch wired improperly?  I've got COM going to the inner lug (pole) of the C&K switch, and OM and CAR going to the outer lugs (2pos).  Am I missing something? 

 

[Matt Nolan]

I think I may have a clue as to what is going on here.

The relay coil, if you're using the one specified, takes about 4mA - the rest of the mic probably draws about 1mA and the bleeder 160k draws about 0.65mA - about 5.7mA total draw on the B+ supply from the node at C9, R8, R7. If you are not using a mic, but using a dummy load for the B+, you also need a dummy load of around 12k for the relay connection, otherwise when you flip the pattern switch to energise the relay, the draw on the overall B+ will drop by 4mA and the voltage will shoot up.

When the pattern switch is set such that the relay is not energised, the 4mA goes through R9 instead, keeping the static current draw on B+ constant.

 

[trans4funks1]

FWIW, I added a "load" in parallel to R7 in a simulation and see that the B+ does indeed drop right down town 105vDC.

:-S

This is the second time I  tried to help and goofed up  this thread. My apologies.

 

[Matt Nolan]

Sorry, I mis-typed in my post above - corrected it now. 12k, not 12 ohms for the relay coil resistance.

 

[geebeeVIE]

Forgive my stupid question,
but: How do I hook up the capsule in this build?