Aikido all in one with ps tube build

[Steve Morley]

Power-up procedure

The chassis should probably go to the house ground as well. The only thing I normally connect to the circuit grounds are the output jack grounds and ground wires from the volume attenuator (at their respective points on the board).

For a cautious start-up disconnect the trans HV leads from the board. Power it up (all tubes in place) and check that the filaments (pre tubes and rect.) are working OK.

Connect the trans HV connectors back to the board.

Connect the output jacks to the board and short the input connections at the board.

Power up the amp while monitoring the B+ voltage. If the B+ goes too high power down quickly. If everything goes OK check the B+ on the pre tubes to see that it's OK. If you know someone with a Variac you can power up gradually.

Measure the AC on the output jacks, it should be near zero.

See my Aikido build on Wall of Sound. It's a different board but might give you some grounding hints. Open the PDF instructions at the bottom of the page for pictures and text of the particulars

Battle of the Cheap Line Stages, Part 4 | Wall of Sound | Audio and Music Reviews

Cheers, Steve

 

[moez]

just hooked up 6.3vac and 5vac to the board only the rectifier lit up nothing on the pre tubes . quickly took some readings here what i got h+,h- pads =1.38 regulator pins input=15.43, output=1.73 adjust=.48

 

[Steve Morley]

Does the heat sink get hot? Check the resistors that set the reg voltage. Is the reg inserted in the correct holes (depends on the side of the board the heat sink is mounted to) buy the looks of the board on the tubecad site. Are the filament jumpers (J1 thru J6 correct for the tubes you are using?

Steve

 

[Steve Morley]

If it's like the other Broskie boards you'll be using J2 and J5 only for 6 volt tubes and a 12 volt heater supply.

 

[moez]

yes i have the jumpers at j2 and j5 ,and a 1.13k at r21 , i think it should be 1.07k there. But if you look at the parts baggie on the second image its the other way around.

 

[moez]

no the heat sink stays cold. this is trans i am using

 

[Steve Morley]

The fact that you have 15.4 volts on the input to the reg suggests that the voltage doubler ps might be working OK. But with that much drop 15.4 - 1.7 and no heat dissipated suggests that the reg is bad or the tube filaments aren't connected properly. You might not get a proper voltage reading on the output of the reg if no current is being drawn.

Where do you live? Send me a PM.

Steve

 

[moez]

so are r21 [1.13k] and r20 [124k] in the right place . in the user guide he mentions if the regulator fails to regulate ,try lowering the the heater voltage a tad from 12.6v to 12v, as the 0.6v might be enough to bring the regulator back into regulation. that would mean changing r21 from 1.13k to 1.07k but only if its in the right place.

 

[moez]

Should the pre tubes light up with only the 6.3v hooked up?

 

[moez]

Sorry ignore that last dumb question. So it ends up the parts bag are labeled correct , but the user guide info is wrong . I switched the 1.13k for 1.07k then put 1.07k in the r20 position and the 124ohm in the r21 spot and all is good. Next is the B+ voltage ,shooting for 220v does that sound about right for the tubes I am using.

 

[kodabmx]

It should work fine. If you don't like it raise the voltage to 250V.

I've built the circuit point to point several times.
I'm running 6N3P/6N6P at 340V and it's excellent but 340V is a little high for a 6N23P, though I've never had a failure but it exceeds the datasheet limits.

 

[moez]

Just measured the B+ at the center of the board and got 288vdc, then across c5 and c4 and got 228vdc , I think that should be good.

 

[moez]

well i finished everything up today and hooked it up to my amps , theirs a little scratchiness and pop in the left channel on start up and changing the volume. Also when i turn it off the sounds stop for a couple of seconds then come back on and slowly dies off ,wierd. Can anybody let me know if these measurements i took while it was running are good , trans is hammond 270ex 550v ct at 114ma 6.3v at 4A, 5v at 3A tubes are 5u4g rectififier 6cg7 input 6n23p-ev output

1. pins 4 and 5 readings are

V1=5.94v
V2=6.04v
V3=5.83v
V4=6.16v
H+ H- =12v
B+=296V
R12a,b=230v with a 3.9k
C5,C4=230v

 

[kodabmx]

The scratchiness could be a bad pot due to the wiper losing contact.

What happens when you turn it off is what I observe with Aikido or SRPP. The coupling cap starts to discharge effectively blocking. You hear a thump, right?


The voltages are close enough, in theory they should all be 6V but variations in the heaters etc. Well within spec.

 

[moez]

No i don,t get a thump when i turn it off , but the music stops immediately for a seconds then starts up again then fades off very slowly seems like almost a minute ,is this something i should be concerned about?

 

[stocktrader200]

do you have a loose heater connection as the 1 minute fade out alludes to?

 

[moez]

I don,t think so ,I checked the leads from the transformer and there all ok, is that what you mean by heater connection?

 

[kodabmx]

I don't hear it as much as see it in the form of a small DC bias, then it stabilizes. The fade out is a combination of the power in the power supply caps, and the signal caps. A minute is weird though, usually the tubes are well cold by then.

 

[moez]

should i be concerned about tube damage with no heater voltage, while a signal is still going thru for that time . i timed how long from the time i hit the power button to complete silence is 35 seconds

 

[Bigun]

no issues - the tubes will be fine. Nice build by the way.