Light Bulb Cap Formers

From cign–(at)–lato.phy.OhioU.Edu Mon Aug 28 20:06:36 CDT 1995
Newsgroups: alt.guitar
From: cign–(at)–lato.phy.OhioU.Edu (Dave Cigna)
Subject: Re: Tube amp question…filter caps
X-Nntp-Posting-Host: plato.phy.ohiou.edu
Sender: postmaste–(at)–lato.phy.ohiou.edu
X-Nntp-Posting-Date: Mon Aug 28 14:12:31 1995
Date: Mon, 28 Aug 1995 18:12:33 GMT

In article <41sk9l$k7--(at)--alph.vnet.net>,
Computer Digest Limited wrote:
>Putman wrote:
>: Hi , i ‘m about to replace the filter capacitors in my Hiwatt
>
>: Also, i remember a post long long time ago about connecting
>: incandescant lights in series with the amp in order to “soften”
>: the blow to the new caps…is this right? if so could someone
>: post the exact procedure.
>
> The series connection you speak of is to reduce the voltage
> seen by the new filter caps. Electrolytic caps need to be
> brought up (the first time) at reduced voltage, so the
> electrolyte inside the cap will form correctly.

The problem with this method is that the resistance of a cold
light bulb is low and increases only after the filament heats up,
but by then it’s too late!

If you don’t have a variac and want to use this method to form
caps, then use bulbs with as low a wattage as you can find.
15 or 20 watt chandelier type would be good, or maybe those big old
Christmas tree lights that nobody uses any more, or even a whole
string of new Christmas tree lights. Wire the bulbs in series with
the power cord on your amp. Remove all tubes except rectifiers from
the amp and turn it on. Monitor the DC voltage across the caps to
make sure that you don’t exceed their ratings.

Leave it on for half an hour or so and measure the AC voltage at
the primary of the power transformer (The ‘auxiliary AC outlet’
is a good place to do this). If it’s no more than about 1/3 of
the wall voltage (40VAC in the US) then you can remove half of
the light bulbs and do it again for another half hour.

Note that if your amp has an international voltage selector switch
(110/220/240 VAC mains) and you’re in the US, then you might be able
to start with the switch in the 220/240 VAC position for lower
voltage on the caps, but I’ve never tried this.

— Dave Cigna

 

Buy the Book!

I cleaned up my tab for Sonny Boy's Help Me and made it into a short book. There's a Kindle version for 99 cents, and if you buy the paperback you get the Kindle free.

Playing "Help-Me" In the Style of Sonny Boy Williamson II: A step by step, note for note analysis of some of Sonny Boy's Signature Riffs

I also write Science Fiction, so you can sample some of my best stories. Also available in Kindle format.


Error Message Eyes: A Programmer's Guide to the Digital Soul
 

A NICE REMAKE OF A FENDER TWEED BASSMAN AMP Logo/Badge

$39.00
End Date: Thursday Mar-21-2019 18:16:21 PDT
Buy It Now for only: $39.00
Buy It Now |
VINTAGE FENDER TWEED TV FRONT DELUXE GUITAR AMPLIFIER

$2,200.00
End Date: Thursday Mar-21-2019 18:30:34 PDT
Buy It Now for only: $2,200.00
Buy It Now |
5 watt tube guitar amp head/ Tweed Princeton 5f2a

$400.00 (0 Bids)
End Date: Thursday Mar-21-2019 18:38:22 PDT
Bid now |
Gibson Ranger GA-20T Tweed Guitar 6V6 Tube Amp Amplifier 1962 (Ben Harper)

$1,875.00
End Date: Thursday Mar-21-2019 18:49:24 PDT
Buy It Now for only: $1,875.00
Buy It Now |
A NICE REMAKE OF A FENDER TWEED SUPER AMP Logo/Badge

$39.00
End Date: Thursday Mar-21-2019 18:56:47 PDT
Buy It Now for only: $39.00
Buy It Now |

 

The JT30 Page Popular links

I began collecting data about the microphones used by blue harp players before there was an internet. I began organizing it into JT30.com in the late 1990s. I accumulated more stuff than I remember. This is some of it.

Street Theory

A Harp Player’s Guide to Music Theory

Learning Harp

Picking Up Blues Harp

A guide to learning to play Blues Harp

Microphone Information

Usenet Articles


Harp Amps

I've been collecting Harp Amps for a while. This is the old Harpamps.com website. There is lots of information here. Here a coupld of links.


Harp Tab

A collection of songs and riffs that I’ve worked out over the years, plus some libraries of stuff I’ve converted to tablature. I’ve included most of the notes and instructions that helped me when I was learning to play blues harmonica.

Basic Riffs Simple harp tabs for songs Blues riffs and phrases.

Harp-L Archives 1992 to 2002


1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003

Harp Frequently Asked Questions