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Topic: Old Lap Steel Question |
Colby Tipton
From:
Crosby, Texas, USA
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Posted 17 Nov 2006 4:47 pm |
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I have an old OAHU lap steel that I was thinking about restoring and I am curious as to why a capasitor would be inline with the volume pot on it. It looks like this was added by a previous owner of the guitar because the routed out wire channel in the body for the wire has been cut out rather ruffly with a drill bit or something.
Colby |
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Blake Hawkins
From:
Florida
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Posted 17 Nov 2006 9:07 pm
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If it is in series with the volume pot,
That is, between the pickup hot lead and the top terminal of the pot, or from the center terminal to the output jack, the cap will serve to decrease the bass output.
Can you read the value of the cap? |
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Colby Tipton
From:
Crosby, Texas, USA
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Posted 18 Nov 2006 6:51 am
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Blake,
This is a Sealdtite paper capacitor.
Capacity D.C. working Mfg. Voltage .05 400.
The number on it is R 8028 and it has a little diode or something that in line on the same wire that is red,green,yellow,black and silver.
The big Sealdtite cap. is 1-9/16" long and 1/2" diam.
Colby |
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Blake Hawkins
From:
Florida
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Posted 18 Nov 2006 7:05 am
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Colby,
That looks like it is an original "tone" cap.
.05 mfd @400 volts D.C. is a common value
for that application. Usually you have
a separate switch or pot for tone control which places the cap across (in parallel)
the signal from the pickup. Connected that way, it will bleed the treble frequencies to ground.
The physical size of the cap indicates that it is very old. Probably '40's or early '50's.
Most all of these caps are defective in some way.
From your description, I gather that the guitar has only a volume control.
A previous owner may have fashioned his own
tone shaping network (EQ) using a fixed resistor and the cap.
Probably removing it will and wiring the pot as a regular volume control will restore the original sound.
Blake |
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Colby Tipton
From:
Crosby, Texas, USA
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Posted 18 Nov 2006 7:56 am
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Blake,
It has a tone control and a selector switch on the back of it. It is very old and the thing puts out a real weak signal but works. The guitar is like a Diana Model with out any fancy art work on it. A friend of mine had seen it out by the road in someones trash and he scavinged it. He said some guys clothes and stuff was out with it. Sounds like somebody got ran out of the house. I have hung on to it for close to 5 years to see if anyone mentioned it around town so I could give it back to them. I think I'm going to sell the whole harness with pick up and all.
Colby |
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Jim Sliff
From:
Lawndale California, USA
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Posted 20 Nov 2006 6:16 am
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| If it sounds weak the pickup may have lost some magnetism over the years, or have a bad coil. I'd have the pickup checked out byJerry Wallace or someone like that, and made usable. Those old Oahus are nice guitars when they work right, and have a full, round tone. |
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Marty Smith
From:
California
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Posted 20 Nov 2006 4:36 pm
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| Is there a switch on the underside of the steel? I have one and there is 2 way tone switch undeer there. |
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Colby Tipton
From:
Crosby, Texas, USA
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Posted 22 Nov 2006 10:33 pm
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Jim,
Yes, i think the magnet post seem real weak.
Marty, yes, it has a tone switch on the underside.[This message was edited by Colby Tipton on 24 November 2006 at 05:19 AM.] |
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Klaus Caprani
From:
Copenhagen, Denmark
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Posted 30 Nov 2006 4:13 am
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The capacitor is probably added to compensate for the apparant loss of tops when rolling back a passive volume pot.
The capacitor is supposed to let the highs bypass the pot. to some degree, it's ideal capacitance being subject to pick-up impedance and the resistance of the pot.
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Klaus Caprani
MCI RangeXpander S-10 3x4
www.klauscaprani.com
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