RARE CAPACITORS, HELP!

[Wizard]

So my B-18 blew up this one resistor in the circuit with one of the 7027a's, thus ultimately causing the 7027a to burn out and my amp to not work.

actually there are three caps i need to replace.

they're a fuckin' doozy to find.

30mfd @ 600vdc
.047mfd @ 1000vdc

i also need a fuse holder for it.

where do i find these things?!

[smallsnd/bigsnd]

ebay?
or
http://www.leedsradio.com/ i guarantee you could find them here, even if they aren't listed on the site.

where are the caps located? and you only listed 2 but said you needed 3...

helpful math:
2 capacitors connected in series will lessen the capacitance and charge storage, but raise the working voltage.
so for example - you could use 2 80mfd/450vdc and you'll end up with a 40mf/900v cap
for the .047 1000v, you could easily use 2 .1mf/500v to get a .05mf/1000v

if the larger caps are for the power section, you could almost definitely raise the caps ratings a little and it probably won't make a difference. using .05 instead of .047 will most likely be inaudible or so close that it won't matter...

[Scruffie]

You can get them here rated to that from the U.K they aren't cheap though by Mundorf http://www.hificollective.co.uk/catalog ... tml?page=1

Sprague Atom Electrolytics get close (500v rating) and are cheaper... probably be ok.

[metalmariachi]

From the values, a B-18 N I presume.

You can use a single Sprague Atom 20uf 600v in place of the 30uf, or 2 in parallel for 40uf. Either would work. I’d go with the 2 in parallel for a tiny bit more filtering.
You can get every thing from Mouser or Mojo Musical supply.

I’m guessing it took out one of the coupling caps from the phase inverter.
There is 360v (+ or -) on the plate of the cathodine pi and 100 on the cathode so any .047 630 v cap would work out fine. Get a pair of Mallory 150s and replace them both.
The reason being is that the remaining one will have drifted in value over the years.

Check the bias circuit especially the 100uf 100v cap. If the coupling cap opened you should be fine but if it shorted first it will have also taken out that cap.

Have fun

MM

[Wizard]

AWESOME YOU GUYS ARE THE BEST I WILL BEGIN MY SEARCH!

ebay?
nd you only listed 2 but said you needed 3...

Check the bias circuit especially the 100uf 100v cap. If the coupling cap opened you should be fine but if it shorted first it will have also taken out that cap.

Have fun

MM

That my friends would be the third cap. Which i actually have a spare of. Which is great.

so yeah. I'm gonna be on the lookout! and i know you don't want no vintage or NOS caps, cuz they've deteriorated even if they;re in packaging.

I'm stoked!

YES

[smallsnd/bigsnd]

good luck!

[Nychthemeron]

Woah, Smallsnd/bigsnd is back! Are you gonna bring back the TAFM? That thing lived up to its name.

[Wizard]

There is 360v (+ or -) on the plate of the cathodine pi and 100 on the cathode so any .047 630 v cap would work out fine. Get a pair of Mallory 150s and replace them both.
The reason being is that the remaining one will have drifted in value over the years.

WAIT

there's two?

is there one on the underside of the board?

[metalmariachi]

No, It’s actually about a ½ inch or so away, should be the next cap closest to the blown one.
Nice mustard (Dijon) yellow cap.
It’s not connected to the other one, it goes to the grid of the unblown tube.
Replacing it will just keep the pair more closely balanced.

MM

[smallsnd/bigsnd]

Woah, Smallsnd/bigsnd is back! Are you gonna bring back the TAFM? That thing lived up to its name.

yeah, been on tour for a month... a newer more fun! version is back! hopefully some will be out before i leave for tour again in november...