... do yourself and the synth a favor and put the value of the cap face up, and make sure the lead isn't smushed up against the positive side of the cap. That way you look like you know what you're doing. ;-)
Changed some resistors today, too. That always takes me back to my early days with Synthfool, when I helped assemble Polyfusion modules. :)
Showing posts with label capacitors. Show all posts
Showing posts with label capacitors. Show all posts
Tuesday, March 17, 2009
Wednesday, February 11, 2009
Wednesday, January 28, 2009
Work pics
I put a few pics on my Facebook account of what I've been doing lately. (Check the labels of this post for hints!)
Wednesday, January 14, 2009
Been doin' the assistant thing lately...
My kitchen table has been my workbench lately. It's perfect for replacing caps on circuit boards and working on keyboard actions. Over New Year's we used said table to assemble the last of the Taurus 1 replacement boards. Lotsa stripping and crimping on my part. :)
I used solder wick for the first time in ages earlier this week. Reminded me of a dozen years ago when I was first learning this stuff. :) I used the power de-solderer today and burned my finger when my hand slipped. Ow!
Never in my wildest dreams did I think I'd do this kind of work *and* enjoy it, but it beats a whole lot of other jobs I've had! ;-)
I used solder wick for the first time in ages earlier this week. Reminded me of a dozen years ago when I was first learning this stuff. :) I used the power de-solderer today and burned my finger when my hand slipped. Ow!
Never in my wildest dreams did I think I'd do this kind of work *and* enjoy it, but it beats a whole lot of other jobs I've had! ;-)
Thursday, August 21, 2008
Thoughts on Capacitors
For today's post, I'm turning over my blog to my husband, 'cause he knows more about this subject than I do.
I recently read a bunch of posts on AH about recapping.
After the laughs and tears subsided, I thought I'd write a few comments.
"I don't get this whole recapping thing"
Obviously you don't. Electrolytic caps have a wet paste in them like a battery.
Like a battery, they can lose their ability to hold a charge or can leak.
They can corrode their conductors from the inside out.
Much like a rusty pail of water, they can appear fine one day and leak the next.
It's well known and accepted that electrolytics do not perform as well over long lengths of time. To not seek that knowledge first before offering a dumb opinion, is itself quite dumb. I've never actually seen a person die from cancer, but thousands do every day.
Btw, how clean do you think that water remains in a rusty pail? ;-)
"You can test the cap in the circuit."
Wrong. Most old caps will read just fine if tested in a circuit or out.
This is because most people are checking them in a static way and are using a capacitance meter. However aged caps can change in how they react to high frequencies and can develop lower resistance than desired.
A cap may measure fine with a meter and fail horribly when actually in a circuit.
Even old polystyrene caps can work 90% fine, but then work poorly at high freqs.
Their "dissipation factor" may not be as good as new and this can affect *just* high freq tracking.
"Replace the tantalums"
On Arps, I wholly recommend this.
But on many other synths, failures just haven't been observed as often.
I've had to replace only one tantalum in Moogs in 15 years.
Replace them if you like, but remember that tants have even more specs to adhere to than electrolytics and they're very expensive.
"Anybody that can solder can replace caps."
What an ignorant statement.
Quite like "anyone that can cut flesh can do surgery."
It's always what someone doesn't know that bites them.
I've seen people replace caps on some synths (Sonic six for example) and not know the holes are not plated through and thus the component required soldering on both sides of the boards.
I've seen people install caps in synths where the leads were left so long, the caps shorted out upon shipping.
I've seen caps installed backwards.
I've even seen full recapping jobs done correctly, but where the synth died because the "tech" screwed up on assembling it correctly afterwards.
"Discharge the caps!"
How ridiculous!
Low voltage caps in low impedance circuits don't need to be discharged.
What little voltage they have will be quickly drained.
Besides not having any voltage left in them about 5 seconds after being powered down, the most they'd have is 20-30 volts on them anyways.
Discharging caps is necessary when working on high voltage devices such as video monitors and TVs. It is not necessary in synths.
A cap in a synth won't kill you. A cap in video monitor with 50KV, might.
"How do we learn if we can't try?"
Try all you want. That's how I learned.
But very few amatuer techs write a followup post how they screwed up their instruments afterwards, so the thought left to many people is that the job is easy.
The fact is, you cannot just decide to do something right. You must practice.
Dentistry, law, medicine, martial arts.. they all look easy from the outside.
But only an idiot tries doing these jobs themselves unless they don't value the outcome.
Most home medical remedies don't work.
Most legal self-defenses fail in court.
Most DIY jobs I've received in are done poorly.
Most people who think they can fight get their butts kicked if the opponent is trained.
It should be mentioned that (imho) Tony at Oakley sound got it right and so did the guy who mentioned lifting traces despite good tools and experience.
I have 34 years of synth experience and still make mistakes now and then.
But the difference with people like Tony and I is that we know how to fix our own mistakes and don't cause as many to begin with.
I recently read a bunch of posts on AH about recapping.
After the laughs and tears subsided, I thought I'd write a few comments.
"I don't get this whole recapping thing"
Obviously you don't. Electrolytic caps have a wet paste in them like a battery.
Like a battery, they can lose their ability to hold a charge or can leak.
They can corrode their conductors from the inside out.
Much like a rusty pail of water, they can appear fine one day and leak the next.
It's well known and accepted that electrolytics do not perform as well over long lengths of time. To not seek that knowledge first before offering a dumb opinion, is itself quite dumb. I've never actually seen a person die from cancer, but thousands do every day.
Btw, how clean do you think that water remains in a rusty pail? ;-)
"You can test the cap in the circuit."
Wrong. Most old caps will read just fine if tested in a circuit or out.
This is because most people are checking them in a static way and are using a capacitance meter. However aged caps can change in how they react to high frequencies and can develop lower resistance than desired.
A cap may measure fine with a meter and fail horribly when actually in a circuit.
Even old polystyrene caps can work 90% fine, but then work poorly at high freqs.
Their "dissipation factor" may not be as good as new and this can affect *just* high freq tracking.
"Replace the tantalums"
On Arps, I wholly recommend this.
But on many other synths, failures just haven't been observed as often.
I've had to replace only one tantalum in Moogs in 15 years.
Replace them if you like, but remember that tants have even more specs to adhere to than electrolytics and they're very expensive.
"Anybody that can solder can replace caps."
What an ignorant statement.
Quite like "anyone that can cut flesh can do surgery."
It's always what someone doesn't know that bites them.
I've seen people replace caps on some synths (Sonic six for example) and not know the holes are not plated through and thus the component required soldering on both sides of the boards.
I've seen people install caps in synths where the leads were left so long, the caps shorted out upon shipping.
I've seen caps installed backwards.
I've even seen full recapping jobs done correctly, but where the synth died because the "tech" screwed up on assembling it correctly afterwards.
"Discharge the caps!"
How ridiculous!
Low voltage caps in low impedance circuits don't need to be discharged.
What little voltage they have will be quickly drained.
Besides not having any voltage left in them about 5 seconds after being powered down, the most they'd have is 20-30 volts on them anyways.
Discharging caps is necessary when working on high voltage devices such as video monitors and TVs. It is not necessary in synths.
A cap in a synth won't kill you. A cap in video monitor with 50KV, might.
"How do we learn if we can't try?"
Try all you want. That's how I learned.
But very few amatuer techs write a followup post how they screwed up their instruments afterwards, so the thought left to many people is that the job is easy.
The fact is, you cannot just decide to do something right. You must practice.
Dentistry, law, medicine, martial arts.. they all look easy from the outside.
But only an idiot tries doing these jobs themselves unless they don't value the outcome.
Most home medical remedies don't work.
Most legal self-defenses fail in court.
Most DIY jobs I've received in are done poorly.
Most people who think they can fight get their butts kicked if the opponent is trained.
It should be mentioned that (imho) Tony at Oakley sound got it right and so did the guy who mentioned lifting traces despite good tools and experience.
I have 34 years of synth experience and still make mistakes now and then.
But the difference with people like Tony and I is that we know how to fix our own mistakes and don't cause as many to begin with.
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