I have some switching rectifiers, numbers are u20d20a and u20d20c. I had to take them off the amp board because they were damaged by the previous person. Is there any offhand substitutes anyone can recommend? Everything I found so far is almost spot on except for 1 spec is off. I just don't know how much of a tolerance any change can have on the board. Any advice would be appreciated.
No one wants to help you get into trouble but if these are power supply rectifiers then it is unlikely that an exact part match is required.
Thinki Semiconductor Product Showcase
Power supply rectifiers are often much better than the circuit requires because diodes are robust and cheap. The diode voltage and current capability must be higher than the circuit operation but does not have to be an exact match of the original part. Being fast switching diodes implies they are used in a switch mode power supply and therefore the replacement must also be a fast diode.
A service manual with schematics is required for a definitive answer. Note that the "A" and "C" parts are reverse polarity and it is critical that they are not interchanged.
The need for the "A" part is something a good engineer would avoid, which is usually not a problem, and raises a lot of question. Again, better information would clear up the situation.
Thinki Semiconductor Product Showcase
Power supply rectifiers are often much better than the circuit requires because diodes are robust and cheap. The diode voltage and current capability must be higher than the circuit operation but does not have to be an exact match of the original part. Being fast switching diodes implies they are used in a switch mode power supply and therefore the replacement must also be a fast diode.
A service manual with schematics is required for a definitive answer. Note that the "A" and "C" parts are reverse polarity and it is critical that they are not interchanged.
The need for the "A" part is something a good engineer would avoid, which is usually not a problem, and raises a lot of question. Again, better information would clear up the situation.
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You need to tell us more about the amplifier, for all we know it might even be a Class G or Class D.
I read this recently and decided to give it a try in an old Valve pre amp.
A Guest Article from Mr. Shirokazu Yazaki: “My Adventure With My Old Marantz Model 7” Part 2. - Jeff's Place
This may or may not be your choice matrix, but I am interested in sound quality above all else, so when I replaced 30 year old electrolytic caps I changed like for like, but when it came to the diodes - I thought well this is expensive, completely unnecessary specification in real terms.. BUT I wonder if they sound as good as described.
Well I am certainly not changing them and they take a while to settle in, but are better sounding than the old ones - and no I never tried like for like new so a biased test perhaps.
They are BIG, EXPENSIVE and over specified, but they do sound nice 🙂
A Guest Article from Mr. Shirokazu Yazaki: “My Adventure With My Old Marantz Model 7” Part 2. - Jeff's Place
This may or may not be your choice matrix, but I am interested in sound quality above all else, so when I replaced 30 year old electrolytic caps I changed like for like, but when it came to the diodes - I thought well this is expensive, completely unnecessary specification in real terms.. BUT I wonder if they sound as good as described.
Well I am certainly not changing them and they take a while to settle in, but are better sounding than the old ones - and no I never tried like for like new so a biased test perhaps.
They are BIG, EXPENSIVE and over specified, but they do sound nice 🙂
I apologize. The amplifier is a class d. The specific brand and model is skar skv1500.
The part u20d20c is common cathode fast switching rectifier.
U20d20a is common anode fast switching rectifier.
Power supply mosfets are irf3205. Output side is irf640n.
Not sure on what other info is needed. I'm just unsure on what tolerances or other parts can be used. I found a set of rectifiers that are 30 amp instead of 20 total per diode. But I'm not exactly sure on how much more amperage the board circuitry can handle. I attached a picture of the amp board in question.
The part u20d20c is common cathode fast switching rectifier.
U20d20a is common anode fast switching rectifier.
Power supply mosfets are irf3205. Output side is irf640n.
Not sure on what other info is needed. I'm just unsure on what tolerances or other parts can be used. I found a set of rectifiers that are 30 amp instead of 20 total per diode. But I'm not exactly sure on how much more amperage the board circuitry can handle. I attached a picture of the amp board in question.
Attachments
V8 overheating
"big lazy V8" engines are notorious for overheating because they do not come with big enough radiators and electric water pump and fan. There is a long hill on highway 5 in BC where muscle cars and RVs die while better designed 4-bangers scoot past.
"big lazy V8" engines are notorious for overheating because they do not come with big enough radiators and electric water pump and fan. There is a long hill on highway 5 in BC where muscle cars and RVs die while better designed 4-bangers scoot past.
operating current
There is about zero chance that the diodes will effect the operating current of the board. Higher current diodes can withstand higher currents but they do nothing to set the current.
There is about zero chance that the diodes will effect the operating current of the board. Higher current diodes can withstand higher currents but they do nothing to set the current.
That was just an example, the bigger part will not be run close to its limit.
And rectifiers are cheap, even the good quality ones are not so costly in terms of price, so I would put the biggest that would fit.
As for V8s, they are mostly out of production.
Talk to an old timer who had to tune a V8 with dual contact breaker points and four Holley carburetors....that would make most youngsters break into a sweat. Tedious is a mild description.
I thought they had belt driven fans and water pumps.
Never did one myself, the old Impalas were scrapped after being converted to diesel for life extension.
Have not seen one since 1992 here.
Gasoline engines were scrapped, as worn out, and truck diesels put, as they were mostly show cars for wedding processions and the like, walking pace.
Then newer cars came, and the cars were also scrapped.
Saw a TV program, Cuba had some interesting old American cars, they were casting the emblems and so on in small workshops if needed.
And rectifiers are cheap, even the good quality ones are not so costly in terms of price, so I would put the biggest that would fit.
As for V8s, they are mostly out of production.
Talk to an old timer who had to tune a V8 with dual contact breaker points and four Holley carburetors....that would make most youngsters break into a sweat. Tedious is a mild description.
I thought they had belt driven fans and water pumps.
Never did one myself, the old Impalas were scrapped after being converted to diesel for life extension.
Have not seen one since 1992 here.
Gasoline engines were scrapped, as worn out, and truck diesels put, as they were mostly show cars for wedding processions and the like, walking pace.
Then newer cars came, and the cars were also scrapped.
Saw a TV program, Cuba had some interesting old American cars, they were casting the emblems and so on in small workshops if needed.
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So if I do go with the slightly higher amperage, i should be fine? Both original rectifier and the closest one I found are identical except for the amperage capacity. They both have a 200v peak, 35ns switch rate, etc. Just the total amperage peak is 10 amps higher. Thanks for the advice. I think this solved my question/concern.
It's impossible to know what other problems you have. But higher rated diodes are very unlikely to be your problem. As I said before, no one wants to help you get into trouble.
If the diodes test out okay in reverse and forward, not the culprit, your fault is elsewhere.
You mentioned damaged by another person.
Then a thorough tracing of the fault, which caused the original repair, is needed.
It can happen that parts are installed backwards or exchanged by a tired or inexperienced person, components may be damaged.
Proceed with care.
You mentioned damaged by another person.
Then a thorough tracing of the fault, which caused the original repair, is needed.
It can happen that parts are installed backwards or exchanged by a tired or inexperienced person, components may be damaged.
Proceed with care.
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