Weird Capacitors! Need help determining replacement value

[waspclothes]

So I've never seen capacitors like this before, in fact I'm not even 100% sure they ARE caps. They're referenced as C on the circuit board along with some other known capacitors though, so I'm to believe they are capacitors. Unfortunately none of them measure any capacitance on my multimeter and I can't understand the markings to determine replacement values. I also can't find a schematic for this amp (Carlsboro solid state amp).

Here's a picture:



The values written on the capacitors are like "100 MN". Any ideas?

[mozz]

Do they measure any resistance? Model number? Problem you are encountering? If they are caps, I can't believe that many would be open, test known good caps with your meter, start at 100pf.

[waspclothes]

Do they measure any resistance? Model number? Problem you are encountering? If they are caps, I can't believe that many would be open, test known good caps with your meter, start at 100pf.

Known good caps measure accurately. These mystery "Caps" all measure OPEN for resistance. This amplifier was making a lot of noise (windy, popping, etc..) and I replaced all of the electrolytic capacitors - it's quieted down but I'm still getting some Popping. The popping isn't affected by the channel volumes or tone controls, but it does go away when the Master vol is turned down.

[Jazz P Bass]

Measuring a small value capacitor with your meter set to read resistance is pointless.

Most caps will read open circuit.
Electrolytic caps will show a reading as the meter voltage charges them up but this is not a valid test of the cap.

If nothing else, go out and purchase a cheap meter that has a capacitance tester.

[pdf64]

I recognise those as caps, though can't recall the technology.
The numbers are probably their value in pF

[Enzo]

They look like common ceramic caps to me. Common in a previous era, yes, but tube TV sets would be full of them. Numbers ought to be cap value in picofards.

[waspclothes]

Measuring a small value capacitor with your meter set to read resistance is pointless.

Most caps will read open circuit.
Electrolytic caps will show a reading as the meter voltage charges them up but this is not a valid test of the cap.

If nothing else, go out and purchase a cheap meter that has a capacitance tester.

Hey JPB, I was measuring them in the capacitance setting but was responding to mozz who asked what they measured in resistance (presumably to see if they're something other than capacitors).

[mozz]

I just mentioned resistance because he wasn't 100% sure they were actually a cap. If they are pf caps, why no meter reading? M could be tolerance 20% and then N stands for nano? Still doesn't answer why would they all be open. How old of a solid state amp? 1965? 1985?

Here are some tube schematics, other page shows some of those caps even on the tube amp models, schematics call them 3kpf, 47kpf.

Carlsbro Amplifier Vintage Wiring Diagrams
Servicing a Carlsbro CS100 Reverb PA Amplifier

[glebert]

Wonder if MN is milli-nano, which would be pico

[rjb]

Wonder if MN is milli-nano, which would be pico

Unless kpf is kilo-picofarad, which would be nanofarad.

[g1]

Does your meter cap setting normally measure down to small values like 50pF ?

[Enzo]

milli-nano??? Now I have heard everything.

[J M Fahey]

milli-nano??? Now I have heard everything.

No Sir, you still need to listen to milli-vanilli

enjoy specially from 0:52 on

[Justin Thomas]

MV... great, now my Master Volume knobs on my amps (built or bought) will be called the "Milli-Vanilli" knob. Because Milli-Vanilli and Master Volumes are equally criminal inventions foisted upon the world.

Juan, that was as horrible as it was 30 years ago when I had to hear it on the school bus. A pox on you for posting that! T-Boy, where's that "HULK SMASH!" button?

Justin

[J M Fahey]

Ok, here´s the antibiotics to cure that ear infection