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riz
Got Rhythm
Joined: 19 Apr 2005
Posts: 73
Location: Bolzano, Italy
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 Posted: Thu Jul 07, 2005 3:24 pm Post subject: I'm back! |
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Don't know if anyone cares though.
Anyway, I wanted to tel 1bassleft that after this long period my bandmaster is ok again, even if sonn I'll have to change the capacitors because they're still original (I'm talking about 41 years old).
The problem was a resistor gone mad, and being that resistor part of the vibrato thing, it affercted the bias circuit as well. Or something like this.
Anyway, it works now.
BUT, I've got a couple of questions.
1) how do you wire 4/5 lightbulbs in series???
this I'm asking because I've got an old electric organ, and my tech (yes I've got one now) told me that switching it on now, after many years, could mess up the capacitors, and to avoid all the tension going into the organ he suggested me to put some bulbs before the organ's power cable, linked in series, wait a bit, take a bulb off and wait, and so one; doing this the tension should go up gradually or at least in steps and allow the caps to charge better, on the mans opinion.
2) ouch, I don't remember the other question now... will do some day.
Thanks for help!!! |
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1bassleft
Lowdown Cack-hander
Joined: 16 Feb 2005
Posts: 3863
Location: "Hit The North"
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| Posted: Sun Jul 10, 2005 12:48 am Post subject: |
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Hello and welcome back, Riz. Sorry for the delay in replying - things have been happening over here.
OK, I understand what your tech's saying. If capacitors have been left "on the shelf" for a while, they appreciate being brought up slowly. The lightbulbs seem an oddly "homegrown" way of doing it. The Variac is more straightforward. Anyhow, to wire up four lightbulbs (or anything else) in series, it goes like this:
The power supply +ve is wired to bulb #1's +ve. Bulb #1's -ve is wired to bulb #2's +ve. Bulb #2's -ve is wired to bulb #3's +ve and so on, until bulb #4's -ve is wired to the power supply's -ve. That is serial.
For parallel, the PSU +ve is wired to bulb #1's +ve, which is then daisy chained to the +ve of the other three bulbs. Bulb #1's -ve is daisy chained to all the other bulb's -ves and the -ve of bulb #4 is wired to the PSU -ve.
To tell the difference, take out a bulb. In parallel, the remaining three bulbs will stil light up. In series, the whole lot go dead (the circuit is broken) until the +ve to -ve loop to the PSU is re-established. |
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riz
Got Rhythm
Joined: 19 Apr 2005
Posts: 73
Location: Bolzano, Italy
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| Posted: Thu Jul 14, 2005 7:54 pm Post subject: |
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uhm, thanks bass, as usual your help ... well, it helps me.
I now understand how things go but the only thing that it is not clear yet is were to put the socket where to plug the amp's powercord into.
and: considering the whole strange thing would be between the wall and the amp, what you've said works for AC as well right?
so: last bulb's -ve would be wired to socket, and the other end of the socket -let's say it's the negative, to continue the circle-has to be linked to the plug's (where we started) free end----I'm getting confused...
just wish this forum had a "drawing tool"...
I know a variac would make things easier but I think it would be way too expensive for my shrinking pockets.
Thanks again, have a nice evening!!! |
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1bassleft
Lowdown Cack-hander
Joined: 16 Feb 2005
Posts: 3863
Location: "Hit The North"
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| Posted: Fri Jul 15, 2005 1:10 am Post subject: |
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Riz, my mistake  . I didn't read properly your crucial phrase:
| Quote: | | he suggested me to put some bulbs before the organ's power cable, linked in series |
I'm sorry - my previous post didn't make much sense. I must tell you that I don't fully understand how to do this properly. I am not qualified in electronics and I've never heard of this procedure. I only pass on what I have understood from techs with better knowledge. If you would like, I can ask for opinions and explanation from friends with theory and experience. Let me know if you would like this information. Myself, I would not attempt the task but perhaps it will be more straightforward if explained properly by the real solder-sniffers  . |
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1bassleft
Lowdown Cack-hander
Joined: 16 Feb 2005
Posts: 3863
Location: "Hit The North"
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| Posted: Mon Jul 18, 2005 12:49 am Post subject: |
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Riz, as I expected, a lot of people I asked said "  " about the idea. Still, there's a guy I know called Rich M and he's given me some useful information.
The basic idea could be better than a Variac for old capacitors, because the Variac doesn't alter the AC much. However, he thinks that lightbulbs don't offer anywhere like enough resistance. A 1Mohm resistor in series is a better bet, and still cheap.
As Rich pointed out to me, it may not be necessary to have lots of bulbs, or lots of resistors. Just as a 25W bulb can be replaced with a 40W, then 60W, then 100W (this is similar to removing one bulb at a time), so a 1M resistor could be replaced by a 500k, then 250k and so on. Even this may be unnecessary; the resistor simply allows the cap to charge up at its own rate, decreasing the initial 'shock'.
As soon as I get more info, I'll pass it on. |
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