What does everyone think/know of these caps?
http://www.ebay.com/itm/190623580064...84.m1423.l2649
(Item # 190623580064)
They are 39,000uf 80 volt Nippon Chemi-Con
I've already contacted the seller and he doen't know more about them than is printed on the outside.
Thoughts??
http://www.ebay.com/itm/190623580064...84.m1423.l2649
(Item # 190623580064)
They are 39,000uf 80 volt Nippon Chemi-Con
I've already contacted the seller and he doen't know more about them than is printed on the outside.
Thoughts??
one more thing...
I forgot to mention in my original OP;
I have a creative way to mount them and I will post pictures once I get them (assuming everyone here says they are a good idea.
Regarding inrush. Yes I have an external current limiter, but may also add the thermistor everyone talks about if I go with this big of caps.
I will write about the diy external current limiter in a separate post soon.
I forgot to mention in my original OP;
I have a creative way to mount them and I will post pictures once I get them (assuming everyone here says they are a good idea.
Regarding inrush. Yes I have an external current limiter, but may also add the thermistor everyone talks about if I go with this big of caps.
I will write about the diy external current limiter in a separate post soon.
Replace the caps with something no bigger than about 10% over what is in there. A pair of 39,000 mfd seems high to me and would probably require a soft start circuit. Trying to replace the stock size caps with something much larger will play hell with the rectifier.
I just put in 22,000 caps from an ebay seller into my DH-120 replacing the original 6600's. Besides being much larger, they have lower ESR. So, I replaced the bridge with a 30A hexfred to take the inrush and added 6800 5W bleeder resistors. The result was a 5 dB drop in LF residual noise and 8 to 13 dB lower 60 Hz harmonics. They fit exactly as the originals.
How much can I attribute to the rectifier, how much to modern caps and how much to just replacing 40 year old dried out caps I can't say. 38,000 do seem large.
How much can I attribute to the rectifier, how much to modern caps and how much to just replacing 40 year old dried out caps I can't say. 38,000 do seem large.
It doesn't seem to be a low ESR unit. Will they physically fit inside the chassis w/o shorting out when you put the top back on?
They sell stuff; volume is their business - not information. Just a fact of surplus electronics.
You seem aware of the current inrush problem. The power switch is usually the first thing to die when you do a big cap upgrade to the power supply. A 35Amp or greater diode bridge is a good idea. HexFRED bridges are usually better, like tvrgeek said, as well as bleeder resistors.
Quite frankly I think you'd do better w/two sets of two or two sets of four 10,000uF 80V "audio" (low ESR) capacitors, two HexFRED diode bridges, and set up a quasi-dual mono power system.
Oh yes, remember to replace that garbage input cap (C1) with a good quality film cap. That's half the battle right there in a DH-200.
Film Cap
per lanchilli and darthbubba's comments above...
"replace that garbage input cap (C1) with a good quality film cap"
I went to digikey and tried to find a film cap of the value spec'd for C1. I plug in 10uF and get lots of choices - all very different and I have no idea which one.
Can someone help me understand which film cap (or features) I want?
Thanks.
per lanchilli and darthbubba's comments above...
"replace that garbage input cap (C1) with a good quality film cap"
I went to digikey and tried to find a film cap of the value spec'd for C1. I plug in 10uF and get lots of choices - all very different and I have no idea which one.
Can someone help me understand which film cap (or features) I want?
Thanks.
Still need to understand better
I am not an electronics person. Sonicap 10uF and what? Honestly I have no idea what to pick from the choices on digikey. And they don't appear to sell Sonicap.
Can you help me with a Digikey part number?
Thanks in advance.
I am not an electronics person. Sonicap 10uF and what? Honestly I have no idea what to pick from the choices on digikey. And they don't appear to sell Sonicap.
Can you help me with a Digikey part number?
Thanks in advance.
Digikey does not have them.
just replace the old 10uf np capacitor with one of these http://www.google.com/url?sa=t&rct=...y_yuCw&usg=AFQjCNET_7YaB4J7FDL3moCmkzrMIFCQbg
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Hey, I don't mean to hijack your thread bigbargain but I am in the same position as you. I have a Crown Comtech 400 that still has its original filter capacitors from 1996. These capacitors are rated for 6300uf @ 200 volts (one per 220 watt channel!!), but this voltage is only necessary if you use the 70v mode on the amplifier (takes 120 volts). Since I will be sticking with 4/8 ohm mode, I'll be dealing with 60 volts instead.
Could I throw a 10,000uf, 100v capacitor in each channel? My 2 rectifiers are rated for 35 amps at 400 volts so I believe that they will be good enough.
What do you think about these Kemet capacitors?
ALS40A103KF100 Kemet Aluminum Electrolytic Capacitors - Screw Terminal
I could also get the cheaper 85c capacitors:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtZ1n0r9vR22WsHOALhvbhWGPa0bfZLODo=
Here is the schematic:
http://www.crownaudio.com/pdf/legacy/ct400_main.pdf
Could I get better performance from upgraded rectifiers by the way?
Thanks!
On topic: Why does your amplifier use such large capacitors? Shouldn't something like 5000uf per 100 watts be sufficient for smoothing?
Could I throw a 10,000uf, 100v capacitor in each channel? My 2 rectifiers are rated for 35 amps at 400 volts so I believe that they will be good enough.
What do you think about these Kemet capacitors?
ALS40A103KF100 Kemet Aluminum Electrolytic Capacitors - Screw Terminal
I could also get the cheaper 85c capacitors:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtZ1n0r9vR22WsHOALhvbhWGPa0bfZLODo=
Here is the schematic:
http://www.crownaudio.com/pdf/legacy/ct400_main.pdf
Could I get better performance from upgraded rectifiers by the way?
Thanks!
On topic: Why does your amplifier use such large capacitors? Shouldn't something like 5000uf per 100 watts be sufficient for smoothing?
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Read here, (love him or hate him, he has an opinion) think about it, form an opinion, then hit eBay. A search for "polypropylene capacitor" turned up 157 hits just now. YMMV.
BTW, you can reduce the cap size to 2uF 50V w/o any problem; that's the size of the DH-220 input cap.
Have fun... 😉
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techbiker, I would use the 105c!. There is not an specific capacitance value for a power supply. it all depends on the design and type of amp (class).
Techbiker.
I don't want you to think I'm ignoring you. However, I may be one of the last people you should ask as there are LOTS of more knowledgeable people on this board (which is why I let your question "bake" a little).
So here is my version of an answer.
First, I am not familiar with alot of different amp designs, so I will only answer from the perspective of what I know (or think I know).
The power supply caps are more appropriately called filter caps. Think of them as very fast acting rechargeable batteries. They discharge into your speakers when the preamp tells them to and are constantly being charged by the power coming from your wall outlet.
Continuing that analogy, the wall outlet does not provide enough current to keep up with the demands of what the pre-amp says to deliver at times, but because a music signal is a sine wave and there are times when the signal to the speakers is lower the capacitor has a chance to charge back up.
However, when the pre-amp instructs the capacitor to dump a lot of current into the speakers, the voltage available from the capacitor begins to drop and that represents distortion (also called "ripple") on the power rails.
Hence, the best way to avoid ripple is to have a bigger rechargeable battery (aka Power Supply Filter Capacitor). Bigger is better.
However, the risk you run as the capacitor gets bigger is from the that very short time when the amp is first turned on and the capacitors must be quickly charged from fully discharged to fully charged. This is called "inrush current" - good name right? That inrush current is the highest amount of current your amp will see. If all the electrical components between the wall outlet and your capacitors survive the inrush of current, your amp will enjoy a good long life (at least that part). Hence the reason why people here talk about the power switch and possibly other protection components failing from inrush.
So, what you are balancing is having a lot of available current to avoid distortion vs. burning up the power switch and a few other components. You can do things to reduce the risk from inrush, but that depends upon how much modification you want to do.
Why are mine so much bigger than yours? I don't know. But I do know lots of folks say to make them bigger.
Probably a good idea to do some google searches and find out what people are doing for capacitor upgrades to your specific amp. And have some fun.
P.S. Be very careful around capacitors. That current charge I talked about can just as easily be dumped into your body and stop your heart! If your going to touch them, be sure to discharge them with a resistor and confirm they're discharged with a meter. When I work on my amp, I clip a volt meter across the caps the whole time, so I can tell at a glance if they're charged.
I don't want you to think I'm ignoring you. However, I may be one of the last people you should ask as there are LOTS of more knowledgeable people on this board (which is why I let your question "bake" a little).
So here is my version of an answer.
First, I am not familiar with alot of different amp designs, so I will only answer from the perspective of what I know (or think I know).
The power supply caps are more appropriately called filter caps. Think of them as very fast acting rechargeable batteries. They discharge into your speakers when the preamp tells them to and are constantly being charged by the power coming from your wall outlet.
Continuing that analogy, the wall outlet does not provide enough current to keep up with the demands of what the pre-amp says to deliver at times, but because a music signal is a sine wave and there are times when the signal to the speakers is lower the capacitor has a chance to charge back up.
However, when the pre-amp instructs the capacitor to dump a lot of current into the speakers, the voltage available from the capacitor begins to drop and that represents distortion (also called "ripple") on the power rails.
Hence, the best way to avoid ripple is to have a bigger rechargeable battery (aka Power Supply Filter Capacitor). Bigger is better.
However, the risk you run as the capacitor gets bigger is from the that very short time when the amp is first turned on and the capacitors must be quickly charged from fully discharged to fully charged. This is called "inrush current" - good name right? That inrush current is the highest amount of current your amp will see. If all the electrical components between the wall outlet and your capacitors survive the inrush of current, your amp will enjoy a good long life (at least that part). Hence the reason why people here talk about the power switch and possibly other protection components failing from inrush.
So, what you are balancing is having a lot of available current to avoid distortion vs. burning up the power switch and a few other components. You can do things to reduce the risk from inrush, but that depends upon how much modification you want to do.
Why are mine so much bigger than yours? I don't know. But I do know lots of folks say to make them bigger.
Probably a good idea to do some google searches and find out what people are doing for capacitor upgrades to your specific amp. And have some fun.
P.S. Be very careful around capacitors. That current charge I talked about can just as easily be dumped into your body and stop your heart! If your going to touch them, be sure to discharge them with a resistor and confirm they're discharged with a meter. When I work on my amp, I clip a volt meter across the caps the whole time, so I can tell at a glance if they're charged.
If you are not an electronics person, I would suggest you keep your hands out from inside an amp without some direct supervision. It is really easy to make mistakes. They go boom. If you don't understand why lower ESR main caps will blow out the bridge, stop now.
The 200 was a really good amp in it's day for it's price. It has some serious shortcomings Erno fixed in his later designs. Remember it is almost 40 years old and was a first generation MOSFET amp. Don't expect miracles.
I was quite pleased with the reduction of 120 Hz harmonics by putting a hexfred bridge in my DH 120. I used a 35A bridge instead of a soft start power up. Expencive part, about $18.
Older amps designs thought bigger caps were better. Designers have learned better. Modern amps have transformers that don't fall on their face so the caps are FILTERS, not energy storage banks as was once thought.
I prefer 600V PIV for rectifiers. It depends on the transformer.
Do you have copies of Erno's later fixes/new designs? He's apparently retired and his web site is gone.
As Sylvester Stallone said to Kurt Russell when Kurt asked the same question (in some otherwise forgettable movie), Sylvester replied: "Genetics" 😀
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