Mcintosh mc-60 missing cap?

allhartfidelity

allhartfidelity

More gear than sense
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Pair of 60's, using 1858 amd up as well as 4496 and up schematics (the amps span both ) both chematics look the same.
Both have listed a capacitor c6 @470mmf no voltage given. This capacitor to straddle r11 a 1.3k resistor. The cap is not present in either amp.
Ive tried to find board layout like the sams photofact. The Sams, does not have mac designations listed so ive changed them to correspond to it. Sams call it c8, and shows it on the back side of the board.
Has anyone gone missing a c6 cap while rebuilding these amps? Any guidence appriciated.
 

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dshoaf said:
It better be there. That is the negative feedback loop!

Cheers,

David
Click to expand...
Just learned that it actually only LOOKS like a resistor. Little lighter in color than carbon comp resistor but is actually a cap. (One next to white wire) Strange to see a cap looking like a carbon resistor. Go figure.
 

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Also, having desired a power switch but not willing to add a hole, im thinking of an option.
As i cut the cord off one amp because it was frayed, i wanted to power it for testing after the rectifier change so i used a double ended cord and went in through the 3amp plug. It occured to me to keep using this cord to power, which is similar in fashion not to having a removable iec. Pull the plastic crimp out of the hole where the power cord was and instal a power switch there. Simple, reversible, very little work. Anyone want the old power cords?
 
allhartfidelity said:
Also, having desired a power switch but not willing to add a hole, im thinking of an option.
As i cut the cord off one amp because it was frayed, i wanted to power it for testing after the rectifier change so i used a double ended cord and went in through the 3amp plug. It occured to me to keep using this cord to power, which is similar in fashion not to having a removable iec. Pull the plastic crimp out of the hole where the power cord was and instal a power switch there. Simple, reversible, very little work. Anyone want the old power cords?
Click to expand...
No, definitely not! Major safety hazard!!
Replace cord and put the switch where the oem nonpolarized power socket resides.
 
Back in the day, it was not that uncommon to see some of the high stability caps use the color code system for identification. It only seems strange today since it is no longer used, or to those who arrived later to the original vacuum tube audio scene!

Great amps!

Dave
 
These tubular ceramic caps were common for small precise values, also used in the Marantz tube amps.
 
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Pio1980 said:
No, definitely not! Major safety hazard!!
Replace cord and put the switch where the oem nonpolarized power socket resides.
Click to expand...
So its safe to have power coming OUT of that socket through a cord, but not safe for power to go IN?
you do realize that the stock power cord is wired directly TO the back side of the socket yes? Just curiouse why its no safe?
 
allhartfidelity said:
So its safe to have power coming OUT of that socket through a cord, but not safe for power to go IN?
you do realize that the stock power cord is wired directly TO the back side of the socket yes? Just curiouse why its no safe?
Click to expand...
It is the double male ended power cord that is not safe. Definitely not recommended!
 
Pio1980 said:
It is the double male ended power cord that is not safe. Definitely not recommended!
Click to expand...
How about a male end in place of where the current female plug is?
Or! A female to female adapter of sorts that locks into the male side?
Thing is, i would have to drill the rivets on the other plug to install a switch there i think, a d the hole left would be huge.
Just kicking the ball around here, trying to learn stuff. Inline power switch was second option, but not sure on the amprage or quality of that type.
 
allhartfidelity said:
How about a male end in place of where the current female plug is?
Or! A female to female adapter of sorts that locks into the male side?
Thing is, i would have to drill the rivets on the other plug to install a switch there i think, a d the hole left would be huge.
Just kicking the ball around here, trying to learn stuff. Inline power switch was second option, but not sure on the amprage or quality of that type.
Click to expand...
There are in line switches up to the task, I'm using a nice one on my Marantz 8 that plugs into the outlet, the amp plugs into the switch. You could Daisy chain two amps to it.
https://www.walmart.com/ip/QVS-Sing...75035&wl11=online&wl12=34214830&wl13=&veh=sem
 
Pio1980 said:
There are in line switches up to the task, I'm using a nice one on my Marantz 8 that plugs into the outlet, the amp plugs into the switch. You could Daisy chain two amps to it.
https://www.walmart.com/ip/QVS-Sing...75035&wl11=online&wl12=34214830&wl13=&veh=sem
Click to expand...
Daisy chain, yes. Would be nice to have one switch for both amps.
Also, while we are here.. the two 12k resistors on the unit. 17 and 19 i think. These being cutrently carbon, and the only 2 i was thinking of metal film for. Mac wants them within 1% of each other, and i can get the films with 1% tolorance so they should drift a lot less yes?
I realize i want to stick primarily to carbon for sound characteristics, but how about just these 2?
Seems a shame to use 5 and 10% tolorance carbon when 1% may not drift as much.
 
Pio1980 said:
These tubular versmic caps were common for small precise values, also used in the Marantz tube amps.
Click to expand...
"Versmic" this equate to in todays terms as ceramic? Unable to locate the term directly, while trying to learn more. Thank you for your conformation that it is indeed a cap.
 
allhartfidelity said:
Daisy chain, yes. Would be nice to have one switch for both amps.
Also, while we are here.. the two 12k resistors on the unit. 17 and 19 i think. These being cutrently carbon, and the only 2 i was thinking of metal film for. Mac wants them within 1% of each other, and i can get the films with 1% tolorance so they should drift a lot less yes?
I realize i want to stick primarily to carbon for sound characteristics, but how about just these 2?
Seems a shame to use 5 and 10% tolorance carbon when 1% may not drift as much.
Click to expand...
Metal film resistors are preferable in any application that carries current, less critical for signal only portions.
 
Pio1980 said:
Ceramic, fat fingers.
Click to expand...
In googling the sprague, and Cornell part numbers of that cap, it was used in tons of Mac, Fisher, televisions ect. 10% 470pf but no voltage given yet. Suppose i can measure whats on it or its position in the circuit to deduce. One looks quite "iffy" so i think what the heck. Rest of the caps are going by by, may as well.
 
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