looking for original 1960s style resistors and WIMA capacitors

[soapfoot]

I doubt think there's a massive reason to suspect counterfeiting efforts.

Probably more likely that the OP is among those who are interested in historical preservation/accuracy (or is among those who attribute--dubiously, in my view--the sound of vintage gear to "magic parts")

 

[soapfoot]

I'm with you on this. Here's a couple of pics of some AB's that needing replacing in a Gates SA38. The 3k3 is nearly 50% out.

On the other hand, I recently bought several A-B carbon composition resistors from a surplus retailer in the US.

Even among the 10% tolerance parts, the vast majority were very close to bogey value... often within 2% or so.

I don't normally use carbon composition resistors anymore (these were for some experiments I'm doing to see whether the voltage coefficient behavior contributes enough low-order harmonic distortion to become significant/audible to me in vacuum tube plate load applications), but I was pretty pleased/surprised by this.

I wonder whether environmental pressures are/can be contributory to carbon resistor drift over time.

 

[zamproject]

I wonder whether environmental pressures are/can be contributory to carbon resistor drift over time.

To me that's the main factor, mostly moisture, carbon substrate resistor is more hydrophilic than other.
The substrate inflate and lower molecules contact, thus increase the electrical resistance.

Recently I had to replace all resistor in a 70 years old tube syth, all of them where out of spec, some with +100% value !

 

[Rob Flinn]

On the other hand, I recently bought several A-B carbon composition resistors from a surplus retailer in the US.

Even among the 10% tolerance parts, the vast majority were very close to bogey value... often within 2% or so.

I don't normally use carbon composition resistors anymore (these were for some experiments I'm doing to see whether the voltage coefficient behavior contributes enough low-order harmonic distortion to become significant/audible to me in vacuum tube plate load applications), but I was pretty pleased/surprised by this.

I wonder whether environmental pressures are/can be contributory to carbon resistor drift over time.

I don't doubt you but on the other hand I think most of the stuff I have had in for repair that uses CC's that is vintage 50's or 60's has needed at the least 1 resistor replaced and often a lot more.

 

[soapfoot]

I’ve experienced similar things! I just find it interesting that new old-stock parts don’t always suffer the same fate

 

[zamproject]

I just find it interesting that new old-stock parts don’t always suffer the same fate

It's probably relative to the storage conditions, especially when we talk about parts manufactured decades ago

 

[gorgon53]

Anyone got any old components lying around?! Specifically, I'm after silver, WIMA capacitors with values 6.8µF, 4.7µF, 1µF, 0.47µF; and resistors of various values. Picture attached gives an idea of what they need to look like. Ideally UK-based.

Thanks!

 

[gorgon53]

are you sure those WIMA caps are film capacitors and not electrolytic caps?

 

[Loetinator]

Hey there
According to old capacitors …
Anyone got an idea what the marking 1k8My might mean ?
( see picture )
Thanx in advance

 

[sr1200]

1.8K or 1800 ohms?

 

[AnalogPackrat]

On the other hand, I recently bought several A-B carbon composition resistors from a surplus retailer in the US.

In CA, AZ, CO, or NM by chance?

Even among the 10% tolerance parts, the vast majority were very close to bogey value... often within 2% or so.

I wonder whether environmental pressures are/can be contributory to carbon resistor drift over time.

Drier climates in the West (central and southern CA) and SW are a possible contributory factor.

 

[JohnRoberts]

Sometimes older is just older....

JR

 

[Loetinator]

1.8K or 1800 ohms?

If it was a resistor - sure but it is a capacitor
Thanks though

 

[Loetinator]

If it was a resistor - sure but it is a capacitor
Thanks though

Ok got it
When i extracted it from its biard i was able to read 1nF - somehow logic when you know

 

[AnalogPackrat]

Ok got it
When i extracted it from its biard i was able to read 1nF - somehow logic when you know

Some caps are marked in pF. 1k pF = 1nF. The other markings may encode dielectric material, tolerances, voltage spec, etc. "MY" may be mylar, for example. Or the M may be the tolerance code (20%) and Y might indicate a ceramic dielectric.