You're welcome...
uf and MFD mean the same thing.
MFD = Microfarads
Here's a handy chart that you might find useful down the road:
http://www.justradios.com/uFnFpF.html
uf and MFD mean the same thing.
MFD = Microfarads
Here's a handy chart that you might find useful down the road:
http://www.justradios.com/uFnFpF.html
Hi Apogee,
I wouldn't go to 68,000 uF from 33,000 uF. That's a big jump in capacitance. I do tend on the side of being cautious though. The rectifiers may need to be replaced with a higher current model. My feeling is that the peak current spikes are already pretty high at 33,000 uF and so is the inductance. For sure a 68,000 uF cap will have to be bypassed.
Also, how do the can sizes compare between the originals and the new ones? It's always better if they fit.
-Chris
I wouldn't go to 68,000 uF from 33,000 uF. That's a big jump in capacitance. I do tend on the side of being cautious though. The rectifiers may need to be replaced with a higher current model. My feeling is that the peak current spikes are already pretty high at 33,000 uF and so is the inductance. For sure a 68,000 uF cap will have to be bypassed.
Also, how do the can sizes compare between the originals and the new ones? It's always better if they fit.
-Chris
anatech said:
While increasing the size of the capacitor would seem to be a good idea, I am going to have to agree with Chris on this one. Those caps are already very big at 36,000uF and the amplifier has been designed with those filter cap sizes, so how much more could I benefit from doubling the size of the filter caps while risking a potentially violent reaction when installed? In addition, those caps, (although I could modify the amplifer and squeeze them in) are 3" in diameter, NOT the 2.5" diameter of the stock caps.
I placed an order for the 68,000uF 100V 3" diameter caps from apexjr, then cancelled it because I really think it is pushing things into a gray area, and I just want my amplifier to function with NO problems and no reservations.
I contacted JEA Capacitors and they found a 100V 36,000uF 2.5" diameter x 4 1/8" electrolytic for me. That is nearly identical in specifications to the original ADCOM discontinued 100V/35,000uF capacitors in the GFA-565. I have no idea about ESR or inductance values but I am going the safe route on this one. I want a stable amp and I can't afford to blow it up now.
Maybe if I get these two fixed, in the future I'll buy a broken one and mess around with it. I am also interested in the future possibility of modifying the power supply with either dual rectifiers or one larger rectifier if possible, and a better quality parallel circuit of filter capacitors.
JEA told me to call back and place the order tomorrow morning, so I will do so. I'm going to order Aluminum Electrolytic capacitors, 100V 36,000uF / 2.5"x4 1/8" dimensions, so it WILL fit.
Capacitor questions:
The smaller capacitors on the AC input soft start board as well as the lytics on the audio input stage....are those capacitors polarized? non-polarized? bi-polar? If I were to replace them, what type of capacitors would I want?
Trying to make sense of all the different types of lytics: http://encyclobeamia.solarbotics.net/articles/capacitor.html
The smaller capacitors on the AC input soft start board as well as the lytics on the audio input stage....are those capacitors polarized? non-polarized? bi-polar? If I were to replace them, what type of capacitors would I want?
Trying to make sense of all the different types of lytics: http://encyclobeamia.solarbotics.net/articles/capacitor.html
Hi mjraudio,
The capacitors on the input boards should be replaced. I have not yet had to replace caps on the soft start board. Most are checking just fine, but you never know. It might be safer for you to simply replace those too rather than wonder about them.
-Chris
Bi-polar and non-polarized capacitors are the same thing. To the best of my knowledge, all those electrolytic caps are polarized.
The capacitors on the input boards should be replaced. I have not yet had to replace caps on the soft start board. Most are checking just fine, but you never know. It might be safer for you to simply replace those too rather than wonder about them.
-Chris
Hi guys,
I figured that larger caps were a jump but also figured we wouldn't have any problems due to the unit already having a soft start circuit.
If it hadn't had the soft start, there'd be no way I would have recommended them.
That having been said, I'm glad MJR was able to find the originals.
I just felt he was moving in the wrong direction buying the smaller ones.
I figured that larger caps were a jump but also figured we wouldn't have any problems due to the unit already having a soft start circuit.
If it hadn't had the soft start, there'd be no way I would have recommended them.
That having been said, I'm glad MJR was able to find the originals.
I just felt he was moving in the wrong direction buying the smaller ones.
Hi Steve,
I have noticed from time to time a performance improvement in the area of 120 Hz residuals once overly large caps are reduced in value. The charging spikes in normal run are lower in level. There are preamp transformers that run warm and buzz in tube amps that settle down once you get rid of the 1,000 uF + supply filter caps.
I am firmly in the camp that there is some optimal cap sizes for different amps. It's a feel thing that I've never bothered to figure out a relationship for.
-Chris
That's fair.
I have noticed from time to time a performance improvement in the area of 120 Hz residuals once overly large caps are reduced in value. The charging spikes in normal run are lower in level. There are preamp transformers that run warm and buzz in tube amps that settle down once you get rid of the 1,000 uF + supply filter caps.
I am firmly in the camp that there is some optimal cap sizes for different amps. It's a feel thing that I've never bothered to figure out a relationship for.
-Chris
Thanks to Apogee and anatech.
I ordered more than enough Cornell Dubilier small electrolytic capacitors (with double-checked & correct values!) to replace the caps on the soft start board. I figure that they are probably far beyond their maximum time usage for a 20 year old amp. Most electrolytic caps are rated to be good for 10 years in optimal temperature settings within the boundaries of their ratings, however, the previous owner stacked components on top of the GFA-565 (a disrespectful and abusive thing to do to a power amplifier) and so I suspect that internal temps may have been responsible for the bridge rectifier and the filter capacitor's failure.
By replacing all electrolytic capacitors in the unit, it should (hopefully) run stably and solidly.
I just took some alcohol swabs and cleaned off all the dust and grime from the inside bottom of the unit, disgusting.
Wish me luck on the rebuild, I just hope that THIS doesn't happen with my 36,000uF @ 100V filter capacitors!
"Okay! Ready to launch!"
"Oh yeah it's like on fire!"
...idiots
I ordered more than enough Cornell Dubilier small electrolytic capacitors (with double-checked & correct values!) to replace the caps on the soft start board. I figure that they are probably far beyond their maximum time usage for a 20 year old amp. Most electrolytic caps are rated to be good for 10 years in optimal temperature settings within the boundaries of their ratings, however, the previous owner stacked components on top of the GFA-565 (a disrespectful and abusive thing to do to a power amplifier) and so I suspect that internal temps may have been responsible for the bridge rectifier and the filter capacitor's failure.
By replacing all electrolytic capacitors in the unit, it should (hopefully) run stably and solidly.
I just took some alcohol swabs and cleaned off all the dust and grime from the inside bottom of the unit, disgusting.
Wish me luck on the rebuild, I just hope that THIS doesn't happen with my 36,000uF @ 100V filter capacitors!
"Okay! Ready to launch!"
"Oh yeah it's like on fire!"
...idiots
Hi mjraudio,
Check things more than twice then. It helps to run a low AC voltage into the amp and measure the polarities across your filter caps. Say about 6.3 VAC or use a variac. Yes, short the softstart resistor.
Yes, you should be fine. One trick I use these days is to take pictures of component locations before I strip the caps out. Digital cameras are great!
-Chris
Check things more than twice then. It helps to run a low AC voltage into the amp and measure the polarities across your filter caps. Say about 6.3 VAC or use a variac. Yes, short the softstart resistor.
Yes, you should be fine. One trick I use these days is to take pictures of component locations before I strip the caps out. Digital cameras are great!
-Chris
A quick little story...
I have this buddy who lives in Southern California. For background, he's a gun nut and also a bit of a redneck. Our conversations always range all topics, and one never knows what will be next. He's a great friend.
This particular night the conversation involved him trying to kill the moles in his backyard with home-made pipe bombs and the fact that his answering machine had died and he wanted to try to fix it.
So, we're on the phone chatting while he was attempting to fix the old answering machine. Long story short, the venture was unsuccessful. He ended up with the circuit board in his hand wondering what he could do with it.
Me, being a good sport, told him to cut the power wire and spread the wire a little bit and plug it in. (understand that I know this guy well, and also how he'd react)
I then had him hold the board facing away from himself and touch the wires to the bottom of a small cap on the board...
I don't think I've EVER heard anyone jump so high laugh so hard. The thing blew up and shot that cap across the room. Well that was it, he was hooked...
We spent the better part of the next hour blowing most of the components off of that board...
Ah, the things one does when one is young...
So about a week later I receive this roughly 12" square box in the mail with no return address. I noticed the lack of return address when I picked it up but opened it anyway wondering what in the heck it was...
As I open the flaps of the box, there was loud pop and a bunch of confetti blew upwards - LOL! He had engineered two levers that had thumb tacks on the end of them that had strings attached to the box flaps. When the flaps were lifted, the levers on the bottom of the box popped the balloon inside...
Sitting under the balloon was the circuit board with a real pipe bomb laying next to it (for me to "try out").
This was sent through the US Mail no less... VERY NICE!!!
I think he had the last laugh on that one...
Now the disclaimer:
And for those of you that are thinking "wow, that would be fun" please just don't even consider going there. I'm now older and wiser and wouldn't recommend anyone else be dumb enough to do this. I actually would ask that you don't even consider it...
Also please note this was sent through the mail many years ago when things were mellow. If someone tried that today, they'd be labeled a terrorist and sent to prison. It was illegal then but now you'd definitely get caught. Be warned!!!!
I have this buddy who lives in Southern California. For background, he's a gun nut and also a bit of a redneck. Our conversations always range all topics, and one never knows what will be next. He's a great friend.
This particular night the conversation involved him trying to kill the moles in his backyard with home-made pipe bombs and the fact that his answering machine had died and he wanted to try to fix it.
So, we're on the phone chatting while he was attempting to fix the old answering machine. Long story short, the venture was unsuccessful. He ended up with the circuit board in his hand wondering what he could do with it.
Me, being a good sport, told him to cut the power wire and spread the wire a little bit and plug it in. (understand that I know this guy well, and also how he'd react)
I then had him hold the board facing away from himself and touch the wires to the bottom of a small cap on the board...
I don't think I've EVER heard anyone jump so high laugh so hard. The thing blew up and shot that cap across the room. Well that was it, he was hooked...
We spent the better part of the next hour blowing most of the components off of that board...
Ah, the things one does when one is young...
So about a week later I receive this roughly 12" square box in the mail with no return address. I noticed the lack of return address when I picked it up but opened it anyway wondering what in the heck it was...
As I open the flaps of the box, there was loud pop and a bunch of confetti blew upwards - LOL! He had engineered two levers that had thumb tacks on the end of them that had strings attached to the box flaps. When the flaps were lifted, the levers on the bottom of the box popped the balloon inside...
Sitting under the balloon was the circuit board with a real pipe bomb laying next to it (for me to "try out").
This was sent through the US Mail no less... VERY NICE!!!
I think he had the last laugh on that one...
Now the disclaimer:
And for those of you that are thinking "wow, that would be fun" please just don't even consider going there. I'm now older and wiser and wouldn't recommend anyone else be dumb enough to do this. I actually would ask that you don't even consider it...
Also please note this was sent through the mail many years ago when things were mellow. If someone tried that today, they'd be labeled a terrorist and sent to prison. It was illegal then but now you'd definitely get caught. Be warned!!!!
I've been doing some even more in-depth reading on electrolytic capacitors. anatech is right in that all of the electrolytic capacitors used in the 565 are polarized. The models used in my particular amp are made by SHOEI, and I cannot find any information on them.
Now, the AC INPUT/BIAS TIME-DELAY PCB (soft start circuit) has live AC leads from the power cord mains voltage coming in and it has little electrolytic capacitors on it (PIC ). Those electrolytic caps have got to be passing AC voltage through them. So don't I have to make damn sure that I replace them with AC RATED electrolytic capacitors? Most electrolytic caps are only DC rated, however, some, for example the Black Gate AC series are AC-rated caps (however they only produce them in 50V varieties). Another note of interest here is that Black Gate manufacturers another series of electrolytic capacitors to be used as "coupling capacitors." How are the capacitors used in the soft start circuit of the 565? Are they used as coupling capacitors? Filtering capacitors?
Okay, the capacitors I ordered to replace those caps on the AC INPUT soft start board are the following:
50V / 220uF
25V / 220uF
100V / 1uF
*A note on Allied Electronics: their ordering system, speed, and service is exceptional. The website lists the manufacturer of these caps as Cornell Dubilier, however, the spec sheets and product pictures show a product made by Mallory. Both products by both companies, I suspect, provide the exact same function as radial polarized electrolytic capacitors, so I don't think it will be a problem and of course I will triple-check each one before soldering them into the board.
1. These are the same values of the original caps (as noted in the service manual and as matched by visual identification of the current caps on the board).
2. They are radial / polarized / electrolytic capacitors just like the originals (I can confirm that the originals are polarized due to the arrow stripe on the PVC jacket indicating the negative lead)
BUT, are the originals passing AC current? Are the originals AC rated? Are my replacements AC rated? Or will they blow up like in the video?
Thanks!
BTW: Apogee, next time make a video of it!
Now, the AC INPUT/BIAS TIME-DELAY PCB (soft start circuit) has live AC leads from the power cord mains voltage coming in and it has little electrolytic capacitors on it (PIC ). Those electrolytic caps have got to be passing AC voltage through them. So don't I have to make damn sure that I replace them with AC RATED electrolytic capacitors? Most electrolytic caps are only DC rated, however, some, for example the Black Gate AC series are AC-rated caps (however they only produce them in 50V varieties). Another note of interest here is that Black Gate manufacturers another series of electrolytic capacitors to be used as "coupling capacitors." How are the capacitors used in the soft start circuit of the 565? Are they used as coupling capacitors? Filtering capacitors?
Okay, the capacitors I ordered to replace those caps on the AC INPUT soft start board are the following:
50V / 220uF
25V / 220uF
100V / 1uF
*A note on Allied Electronics: their ordering system, speed, and service is exceptional. The website lists the manufacturer of these caps as Cornell Dubilier, however, the spec sheets and product pictures show a product made by Mallory. Both products by both companies, I suspect, provide the exact same function as radial polarized electrolytic capacitors, so I don't think it will be a problem and of course I will triple-check each one before soldering them into the board.
1. These are the same values of the original caps (as noted in the service manual and as matched by visual identification of the current caps on the board).
2. They are radial / polarized / electrolytic capacitors just like the originals (I can confirm that the originals are polarized due to the arrow stripe on the PVC jacket indicating the negative lead)
BUT, are the originals passing AC current? Are the originals AC rated? Are my replacements AC rated? Or will they blow up like in the video?
Thanks!
BTW: Apogee, next time make a video of it!
I'm happy! (See?)
I'm intentionally overanalyzing this because, before a few days ago, I didn't know the difference between a diode, resistor, electrolytic versus film capacitor, etc...And I'm messing around with potentially lethal voltages in a very expensive amp. I want this to work so much and try to make sure that the amp does not turn into a
Ahhhh I see! I did notice those diodes on the ac board and after looking at different pictures of diodes on the wikipedia article, I see that some do rectification discretely and that a "bridge rectifier" is not the only type of rectifier.
I just ordered two 100V 36,000uF 2.5" diameter filter caps from JEA Capacitors in NY, which should hopefully work.
Before you were saying that a 68,000uF set of filter caps is a big jump is capacitance and may cause problems in the amplifier. What are the benefits and disadvantages of choosing such a high value capacitor? And also, what could any potential problems be? Would the bridge rectifier not be able to handle them? Could I upgrade it to a higher-rated one?
Thanks in advance.
(See?) I'm intentionally overanalyzing this because, before a few days ago, I didn't know the difference between a diode, resistor, electrolytic versus film capacitor, etc...And I'm messing around with potentially lethal voltages in a very expensive amp. I want this to work so much and try to make sure that the amp does not turn into a
Ahhhh I see! I did notice those diodes on the ac board and after looking at different pictures of diodes on the wikipedia article, I see that some do rectification discretely and that a "bridge rectifier" is not the only type of rectifier.
I just ordered two 100V 36,000uF 2.5" diameter filter caps from JEA Capacitors in NY, which should hopefully work.
Before you were saying that a 68,000uF set of filter caps is a big jump is capacitance and may cause problems in the amplifier. What are the benefits and disadvantages of choosing such a high value capacitor? And also, what could any potential problems be? Would the bridge rectifier not be able to handle them? Could I upgrade it to a higher-rated one?
Thanks in advance.
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