scott2000
Well-known member
gyraf said:
Ok. I get it...Hazing....lol
Federal AM864 troubleshooting help
- Thread starter soundguy
- Start date
Help Support GroupDIY Audio Forum:
Ok. I get it...Hazing....lol
scott2000 said:
Not hazing you. The post you replied to is from *2005*! The author is no longer around here. You are very unlikely to get a reply.
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> Did you use (1) 10u for B and (1) 10u for C? I wasn't sure because of the 22u for A..
The original schematic (which did work) shows three 12uFd caps, two in parallel at "B+C".
12uFd is no longer a standard value.
While modern 10uFd will probably work (their tolerance is better), what WILL work is three 22uFd, two parallel at "B&C". You could instead go A=22uFd, B&C= one 47uFd; but you probably get a better price on a handful of 22uFd than on a mixed-values order.
The voltages in this thing are NOT critical. 187V is same-as 200V. All old schematics note that voltage may vary +/-20%.
Yep. And I'd add while antique cap values might be +/-20% or +100/-20%, just about every modern electrolytic cap I buy in reality tests 0 to -5% tolerance, very very rarely above value. With that old +100% being reality at one point, pick the 22mfd. Two of them will be fine to cover all three original, if chasing 'accuracy'.
scott2000
Well-known member
emrr said:
Thanks! I picked up (2) 10u and (2) 22u so I'll do (1) 22u at A and (1) 22u at B=C..... I didn't know if the whole parallel thing was used for any special reason...like lower esr or something.... Thanks Again....
> parallel thing was used for any special reason...like lower esr
3*12uFd was a standard "can cap" (three caps in one can). That used to be the cheapest way to go.
Ideally the "optimum" balance is with the total uFd equally divided among the nodes. Here 18uFd L 18uFd. However 2*18uFd may not have been near any standard part (3-cap and 4-cap cans were quite common).
There are also changes in "fashion". Cap-cans were moving to 40-40-20uFd as new designs favored larger caps. What happens is the cap-factory is caught with an over-supply of older values which are not selling well. A savvy designer will ask his distributors "what's cheap?" and work with that.
This isn't rocket-to-Mars stuff. More like propping-up the dog porch. Maybe a really big porch suggests two 18" beams. But when I go to buy lumber I learn I can buy three 12" beams for less than two 18" beams. And in the current market of low-price caps I can buy the equivalent of several 22" beams for very little money, and be sure the dogs won't bounce the floor.
FWIW, I never heard of ESR in those days. Caps were either good or they were open. This design is NOT ESR critical. It is the audio equivalent of a dog-porch.
3*12uFd was a standard "can cap" (three caps in one can). That used to be the cheapest way to go.
Ideally the "optimum" balance is with the total uFd equally divided among the nodes. Here 18uFd L 18uFd. However 2*18uFd may not have been near any standard part (3-cap and 4-cap cans were quite common).
There are also changes in "fashion". Cap-cans were moving to 40-40-20uFd as new designs favored larger caps. What happens is the cap-factory is caught with an over-supply of older values which are not selling well. A savvy designer will ask his distributors "what's cheap?" and work with that.
This isn't rocket-to-Mars stuff. More like propping-up the dog porch. Maybe a really big porch suggests two 18" beams. But when I go to buy lumber I learn I can buy three 12" beams for less than two 18" beams. And in the current market of low-price caps I can buy the equivalent of several 22" beams for very little money, and be sure the dogs won't bounce the floor.
FWIW, I never heard of ESR in those days. Caps were either good or they were open. This design is NOT ESR critical. It is the audio equivalent of a dog-porch.
scott2000
Well-known member
This isn't rocket-to-Mars stuff. More like propping-up the dog porch. Maybe a really big porch suggests two 18" beams. But when I go to buy lumber I learn I can buy three 12" beams for less than two 18" beams. And in the current market of low-price caps I can buy the equivalent of several 22" beams for very little money, and be sure the dogs won't bounce the floor.
FWIW, I never heard of ESR in those days. Caps were either good or they were open. This design is NOT ESR critical. It is the audio equivalent of a dog-porch.
[/quote]
Got it....Thanks So Much !
FWIW, I never heard of ESR in those days. Caps were either good or they were open. This design is NOT ESR critical. It is the audio equivalent of a dog-porch.
[/quote]
Got it....Thanks So Much !
