Oh Dear...Replacement needed for Caiman big smoothing cap?

[Alex_UK]

Alex UK

When did Avatar start practising the Dark Arts ?
How many goats had she sacrificed when you caught her on camera ?

She does look a bit freaky, doesn't she!? Afraid no Bovidae were harmed in the making of my current avatar - a few pots of poster paint bit the dust, though!

[Gazjam]

Happy Ending Update...

Burst cap removed and PCB all cleaned up.
22uf 20V Os-Con cap soldered in to replace the big smoothing cap.

All working just fine


SOME PICS:

the burst cap - look at the sweat on that baby!



This was what I saw when I removed the damaged cap...corrosion setting in? Yuk!




All clean and shiney, new cap soldered in.




First bit of DIY, I soldered the cap in, working fine, no explosions or loud bangs..not bad for a first DIY job!
The Beresford's been off for over a week, so I'm leaving it "cooking" for a couple of hours then I'll have a proper listen.
Right away though...just firing it up to make sure its working ok, its sounding better than I remember it.
A proper listen with a glass of vino tonight.

Phew! So...the story comes to an end.
Panic thinking I'd buggered my Dac, a bit of support and help from the guys on here (Thanks Mark..and Mark!) and now I have a working upgraded Dac .

A few changes made at once, hard I guess to pin down what has made it better?
Smoothing cap removed replaced by a low ESR OsCon cap and a better linear supply with Mark Grant mains cable.
Whats made the most difference? Who knows....(who cares!)
Looking forward to a good listen later tonight.

Result.

Thanks guys for all the help on this one, saved my Dac and me a heart attack!

[MartinT]

Nice one, Gaz. Glad it's all sorted.

[Reid Malenfant]

The Os-Con really does look like a bit dropped off in that position, but in reality it's perfect for the job! Having too large a capacitance following a linear PSU can sometimes make things unstable due to the feedback around the PSU circuit itself.

As i mentioned in the PM Gary the cap will be a bit leaky current wise for a while but will settle in. You should notice a gradual improvement in audio quality as it does so

Have a pleasant weekend! biggrin.gif

[MartinT]

Great sounding caps, Os-Cons, but a bit sensitive to being run near their voltage rating. 20V should have a good margin, however.

[Puffin]

Good stuff Gaz. What's your next project?

[Gazjam]

Good question Rob!

Been looking at John Swensons design for a linear PSU for the Touch...remember you sent me the links for it?
hmnnn.

[Puffin]

Good question Rob!

Been looking at John Swensons design for a linear PSU for the Touch...remember you sent me the links for it?
hmnnn.

Ask Jerry if he still likes his.

[Gazjam]

Actually scratch that Rob, the next job is swapping out the Murata 12V reg for a non switching discreet type, probably one of the Dexa'a.

Theres a low high freq "whistle" in the background after fitting the Gator board, and after asking around it seems to be switching noise being picked up by the Gator board, as its not there with the original.
Any other potential reasons for this?

I had assumed the Gator board to be the culprit but as the whistle is there with two different units (and different psu's), I guess its just my Dac with all its modifications adding up to the noise.
Maybe a case of with the Gator board its a more open window letting more crap in?
Dunno...

Going to swap out the Reg anyway methinks.

Baby steps....before I take on a PSU build project!

[Puffin]

Gaz, you ought to make one of the super regulators with a 7805. Have a look on Pink Fish. I can send you the bits you need. Costs about £10. Mind you, you could be waiting a long time if my performance with the caps for the passive mod is anything to go by