Pumpkin preamp - ordered by Steen , official making thread

[Zen Mod]

I'm saying that you can't measure with DMM current in RF range

that's what is inducing excessive ripple

 

[KatieandDad]

That is outside my expertise. I've got a 100MHz scope and a DMM.

The DMM is showing that everything is OK. The scope is showing that it isn't. The results audibly are horrible.

 

[KatieandDad]

If there was serious oscillation occuring, I would expect the devices to get hot. Nothing is any warmer than expected.

Where is the 100Hz ripple coming from.

 

[KatieandDad]

Just waiting for components to arrive before building a solid PSU to see how the Pumpkins perform.

 

[Itsmee]

If you connect your scope across R7 of the Shunty, you will be able to see the current waveform as a voltage.

Just make sure the Shunty 0V is not connected to earth, because the scope probe ground connection is earthed.

 

[buzzforb]

After DCB1, i have appetite for shunty regs. How would you guess your shunty perform against salas' SSLV1 BiB? I now have great respect cor both opinions an ddesigns. Your regulator seems to do more on the eseries element of the regulator, adding to wonders of shunt portion. KatieandDad, your at fault, sorry, but i would bet money on it.

 

[KatieandDad]

I didn't manufacture the faulty PCBs. Everyone of them had a multitude of copper whiskers.

 

[KatieandDad]

I've started a thread "Pumpkin Problems".

This is not intended as a slanging match but to get these potentially lovely boards to work as intended.

 

[Russellc]

I've started a thread "Pumpkin Problems".

This is not intended as a slanging match but to get these potentially lovely boards to work as intended.

Where is this thread?

Russellc

 

[KatieandDad]

http://www.diyaudio.com/forums/analogue-source/203215-pumpkin-problems.html

 

[10y]

Hi,

I have finished my four shunty and pumpkin boards.

The shuntys work perfectly.

The pumkins have this problem: releved at the output of three of output cap DC wandering under 100 mV. Removed one of the 4,7 uF MKC and with the bypassed little MKC cap DC at output wander around 2 mV.
Tryed other plastic cap and always DC rises proportionally at cap value.

Only one C4 output shows DC zero value

What do you think about that?

Thank you.

Ciao,
Anto

 

[KatieandDad]

I've got a thread going - Pumpkin Problems - you might like to add your comments there.

My faults have ALL been down to faulty PCBs. Look VERY VERY carefully for minute whiskers of copper.

 

[10y]

Hi,

I have finished my four shunty and pumpkin boards.

The shuntys work perfectly.

The pumkins have this problem: releved at the output of three of output cap DC wandering under 100 mV. Removed one of the 4,7 uF MKC and with the bypassed little MKC cap DC at output wander around 2 mV.
Tryed other plastic cap and always DC rises proportionally at cap value.

Only one C4 output shows DC zero value

What do you think about that?

Thank you.

Ciao,
Anto

 

[10y]

sorry for the reposting !

For KatieandDad,

I do not thing that my problem is quality pcb related.

Ciao,
Anto

 

[KatieandDad]

Mine looked perfect too. How different they looked whan looked at under a stong magnifying glass.

 

[KatieandDad]

I've still got a strange "Whooshing" noise that I can't track down.

 

[10y]

Hi,

Discovered a little shortie at one r29 so relative output was shorted to ground.
Now all four cap output shows DC.
Anto

 

[KatieandDad]

See what I mean !!!

 

[10y]

yes, but why this DC at output ?

 

[KatieandDad]

It depends on what R49 was actually shorted to.