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67.100.209.21
anyone know where to get a McIntosh MC-60 power supply B+ choke? Also does anyone know the value of the the plate chokes on each 6550? I vaguely remember them being 7uH on one 6550 plate and 8uH on the other 6550 plate.
Follow Ups:
Look in the Allied Electronics Catalog Under " IHD High Current Axial Lead Inductors ". That is the widest value selection I've ever seen. They have 6.8 and 8.2 uHYs, good for 3A., at about $2.00 each. IHD is a Vishay company.Cheers.
Jeff Medwin
Eric
Steve is correct on the choke values but what I did was go to radio shack and got a 2mh choke and it works well...If you dont have the chokes on the plates,the amp will oscillate and motorboat like all get out.
The big choke is 8hy I belive and hammond would be a good bet..I have 4 mac mc60s and one was born without the big PS choke but it has the holes to mount one in it..The unit also has a pair of neon bulbs on the chasis.You dont need the choke persay but its nice to have..Now some companies built it into the power trans.
Mike:Surely you meant to type 2uH and not 2mH. 2mH is pushing 1000X the value of the original chokes. 2mH would be excessive don't you think esp since this effectively adds to OPT primary leakage inductance, the very parameter the Mac bifilar winding is designed to reduce. Also, FWIW, SAMS lists the PS choke @ 1.8H/37ohm. My own meas pretty much verify this value.
Yes steve
I meant 2uh..Im still reeling from the experience with the 29 dollar cd player on the reference system lol.
Steve 1.8 makes more sense and the citation 2 is .7h and Im thinking of another amp thats 8h and maybe w5m..I have too many amps.
Yes steve
I meant 2uh..Im still reeling from the experience with the 29 dollar cd player on the reference system lol.
Stock plate chokes are 1.5 & 2.7uH. As you know, these are of molded construction. The only readily avail replacements I'm aware of are open type by JW Miller and avail from Mouser last I looked. Std values avail are 1.5 & 2.5uH.Easiest/cheapest source for PS choke will probably be Hammond. Choose one close in value and ratings with exact mounting dimensions so you don't destroy the value of the amp by drilling non-stock holes in the chassis. You could also have one custom wound but this will be expensive.
IHD ( Allied catalog ) makes a dandy, exact value 1.5 and 2.7 uHY high current axial lead inductor, low DCR and sweet, $2.00 each.Cheers.
Jeff Medwin
Jeff:I checked out the chokes you reference. Although they might work OK, they're not really a good choice IMO.
Being circuit savy, you know that we're not speaking of PS chokes here but something that might be considered an extension of the OPT primary windings. Theses chokes are in series with the OPT primary windings and are somewhat lossy, apparently by design. AMOF, the Mac originals have a DC resistance of quite a few ohms. The IHD chokes you suggest are wound on ferrite cores and possess a very low DC resistance plus relatively high "Q". The Miller chokes I suggest are wound on phenolic cores, have moderate DC resistance (although lower than original) and possess a lower Q. Also, FWIW, the Miller chokes are what SAMS specifies as a replacements and what the Mac service dept supplied as replacements when they were still supporting these things. This is a case where vanishingly low DC resistsnce is probably not a good thing.
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