matt_uk said:
I would measure the +terminal of the caps to a ground line with a multimeter, set the voltage setting of the meter higher than the markings on the cap. If there is voltage then I will use my rig a few 5W/10W white coffin resistors in series with aligator clips and use one hand only clip the aligators to the terminals of the cab one at a time. Measure again, repeat discharge if need to, measure again.
Chris
matt_uk said:
I usually use the screw-driver method for caps less than 1000u and 50v. anything bigger, I use a 180ohmpower resistor to discharge it initially and then a 0.47ohm power resistor to finally discharge it.
I would think the huge amount of current when the cap is shorted can do some serious damage tot he cap as well as the screwer driver,
Some good, a novice like me would say, literature on power supplies:
http://sound.westhost.com/power-supplies.htm
http://www.tnt-audio.com/clinica/ssps1_e.html
http://sound.westhost.com/psu-wiring.htm
http://sound.westhost.com/power-supplies.htm
http://www.tnt-audio.com/clinica/ssps1_e.html
http://sound.westhost.com/psu-wiring.htm
Interesting information on selecting power supply capacitors:
www.stephenwmoore.com
(bottom of page under electronics)
www.stephenwmoore.com
(bottom of page under electronics)
"Bigger caps will generally improve the bass in an amplifier"
I really think this should be qualified to say that this is the case--
*IF AND ONLY IF*
the amp's power supply has inadequate capacity to start with.
I read of too many cases (on other forums mostly) where someone with minimal experience or knowlede wants to replace existing cap with bigger ones in amn amp that most likely won't benefit from it. It's a kind of mentailty that says bigger caps are always better. Apart from being a wast of time and money, it also encourages some people to butcher their amps. I have personal knowlege of at least one person that pretty thoroghly trashed a decent piece of equipment because a "friend" encouraged him undertake amplifier surgery armed with a screwdriver and a soldering iron but little experience.
Before just digging in and replacing components, be they cap, opamps or whatever, I suggest one as technically specific answer to the question "What's wrong with what's there now?" "i want better sound." a perfectly reasonable desire, but to do anything effective regarding it first one needs to have a pretty good idea about what the unit does not already "sound better".
This point of view comes in part from personal experiences of the past that led to turning highly acceptable situations into highly unaccceptable ones.
I really think this should be qualified to say that this is the case--
*IF AND ONLY IF*
the amp's power supply has inadequate capacity to start with.
I read of too many cases (on other forums mostly) where someone with minimal experience or knowlede wants to replace existing cap with bigger ones in amn amp that most likely won't benefit from it. It's a kind of mentailty that says bigger caps are always better. Apart from being a wast of time and money, it also encourages some people to butcher their amps. I have personal knowlege of at least one person that pretty thoroghly trashed a decent piece of equipment because a "friend" encouraged him undertake amplifier surgery armed with a screwdriver and a soldering iron but little experience.
Before just digging in and replacing components, be they cap, opamps or whatever, I suggest one as technically specific answer to the question "What's wrong with what's there now?" "i want better sound." a perfectly reasonable desire, but to do anything effective regarding it first one needs to have a pretty good idea about what the unit does not already "sound better".
This point of view comes in part from personal experiences of the past that led to turning highly acceptable situations into highly unaccceptable ones.
Discharging Damage?
I just accidentally let the screw terminals of two 22000uf 100v capacitors touch together, I got a got a big spark and it made me jump!
I bought them on ebay and they arrived by post today, I didn't expect them to be charged and carelessly let the terminals touch.
Am I likely to have damaged them? and if so how can I check?
I just accidentally let the screw terminals of two 22000uf 100v capacitors touch together, I got a got a big spark and it made me jump!
I bought them on ebay and they arrived by post today, I didn't expect them to be charged and carelessly let the terminals touch.
Am I likely to have damaged them? and if so how can I check?
I have a Soundcraftsmen PR-800 that has at least one dead power supply cap. The ones that are in there were made by EL CAP and they are 11000MFD 75VDC 80C. They measure 2"dia. X 3.625". I can't seem to find any 11000MFD and the other thing I'm concerned about is that, measuring the voltage of the good cap, it measures 92VDC. Seems like I should maybe be using a 100VDC cap instead of 75VDC. Panasonic make a cap that is the right size physically, but it is 15000uF, 100VDC, 105C. Do you think this will put too much of a strain on the bridge?
Also, does anyone know where I can buy these? They are listed here on Panasonics website, but I can't seem to locate a supplier for them.
Thanks, Terry
Also, does anyone know where I can buy these? They are listed here on Panasonics website, but I can't seem to locate a supplier for them.
Thanks, Terry
still4given said:
Digikey has a Panasonic cap, different type, 10000 uF 100 V, which fits your size requirement. Near the bottom of the page:
http://dkc3.digikey.com/PDF/T043/0827.pdf
Cheers,
Francois.
Capacitors generally have a tolerance rating of +- 20% so on a 10,000uF cap you could theoretically get anything from 8,000uF to 12,000uF so I wouldn't worry too much
If your other caps are only rated at 75V and you are putting 92 V across them, then I'd be looking to replace all of them anyway!!!
Is this 92V measured +ve to -ve rail, or +ve to zero volts rail, -ve to zero volts rail (assuming a + zero - supply)
Tony.
If your other caps are only rated at 75V and you are putting 92 V across them, then I'd be looking to replace all of them anyway!!!
Is this 92V measured +ve to -ve rail, or +ve to zero volts rail, -ve to zero volts rail (assuming a + zero - supply)
Tony.
This voltage is on the + cap. The - cap is not working from what I can tell It reads about 62VDC and 27 VAC. The + cap has no VAC, just VDC. This is measured with the amp turned on but with nothing connected to input or output.. I tried connecting speakers but just get a loud hum out of both sides. I am hoping this will be well after I get the PS straightened out but will cross that bridge once I get there.
Someone said that the Phase Control Regulation in these amps may be causing the voltage to go high because of the dead cap, i.e. the power transformer is being pushed up to full power because of it. I guess I'll see when I get some good caps in it.
Blessings, Terry
Someone said that the Phase Control Regulation in these amps may be causing the voltage to go high because of the dead cap, i.e. the power transformer is being pushed up to full power because of it. I guess I'll see when I get some good caps in it.
Blessings, Terry
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