Bigbottle Phonostage Builders thread.

[Scotty38]

the jumper on the board is to enable valve type change, the load (L & R) is for resistance or capacitance as needed for MC/MM.

 

[Scotty38]

My board arrived today, case in progress and transformer ordered... So it begins....

 

[Bigman80]

Just in case anyone is interested, I'm selling off some very closely matched BF862, Whichbwere ordered from Farnel a few years ago when this project started.

£10 a pair, delivered in the UK

 

[nielsek]

In that photo a number of the solder joints look "cold" and/or starved to me.

For instance:

D6P

HS2P (middle)
HS1P (right)
R6P (bottom)
C4P

Maybe these are good from the other side. I'm just seeing what I can see. Worth checking?

Today resoldered all the joints and no change, HT is still 218-220V when measuring from C4P.

 

[nielsek]

On the red wires you should have around 175V AC.
Check D5,6,7 and 8 for polarity.

Polarity is correct and on the red wires I have 175V AC.

 

[nielsek]

I guess there is some CRC filtering , you could play with resistance to bring voltage to required level but I'd investigate current draw beforehand

Thanks, how can I investigate current draw?

 

[slav]

Thanks, how can I investigate current draw?

You need to ask designer to see if I'm correct about CRC filtering and check if the voltage drop on said resistor is as required , if not there might be a culprit elsewhere on your board .
I didn't follow this thread lately , what's the difference between measured and designed voltage ?

 

[Bigman80]

Just in case anyone is interested, I'm selling off some very closely matched BF862, Whichbwere ordered from Farnel a few years ago when this project started.

£10 a pair, delivered in the UK

View attachment 841625

Gonna have to pull these from sale after receiving a report of a noisy Fet.

I have had them a long time so best to leave them here.

 

[Vivant]

HT should be around 240V DC, with about 10V drop across R9P, 390 ohms.

So total operating current is around 25mA.

 

[slav]

Thanks, how can I investigate current draw?

as per Alan's post check voltage drop on that resistor , check unloaded secondary voltage , what is transformer regulation- at what current your transformer achieves rated voltage?

 

[sebmeb]

Just in case anyone is interested, I'm selling off some very closely matched BF862, Whichbwere ordered from Farnel a few years ago when this project started.

£10 a pair, delivered in the UK

View attachment 841625

Would you deliver to Denmark ??

 

[nielsek]

HT should be around 240V DC, with about 10V drop across R9P, 390 ohms.

So total operating current is around 25mA.

There is 10V drop on R9P, but from 212V to 202V.

 

[nielsek]

as per Alan's post check voltage drop on that resistor , check unloaded secondary voltage , what is transformer regulation- at what current your transformer achieves rated voltage?

I checked transformer's voltages, while unloaded and disconnected from phonostage:
secondary: 10,3V
primary: 180V
Which current should I measure, before transformer or after? If latter, then which one, secondary or primary?

 

[Marra]

Would you deliver to Denmark ??

See post 228.

 

[slav]

I checked transformer's voltages, while unloaded and disconnected from phonostage:
secondary: 10,3V
primary: 180V
Which current should I measure, before transformer or after? If latter, then which one, secondary or primary?

When you remove valves from the sockets what's the voltage on first capacitor?

 

[slav]

Check also voltage on that resistor

 

[nielsek]

232V, measured from the capactior C4P and also from the resistor R9P. No 10V drop there though.
Are this voltages normal and my problem might be tube related?

 

[slav]

Sorry ,due to Alan’s certain activity towards myself elsewhere I cease my interest in building this phono stage and posting in this thread so don’t be offended if I won’t reply when quoted anymore , please direct all your questions to the designing team .

 

[Vivant]

232V, measured from the capactior C4P and also from the resistor R9P. No 10V drop there though.
Are this voltages normal and my problem might be tube related?

232V seems OK but it shouldn't drop much under load, when the valves are in.

 

[nielsek]

232V seems OK but it shouldn't drop much under load, when the valves are in.

Thanks for helping out.
Should I get some other tubes and test with them? ECC83 instead of 6N2P maybe?. V1 voltages are OK, V2 and V3 are off.
You mentioned also to measure current, but from where?