07-26-2013, 04:27 PM
It may not be necessary to replace all resistors. Many old resistors stay very close to their original values, but many others drift high. If you have an ohmmeter, you can measure them and reject any that are too far out of spec.
"Too far out or spec" is a matter of opinion. Many restorers keep anything within 20% of spec, but I am a little pickier. If a resistor is outside of 10%, I'll usually replace it. If it is a 5% part and out of spec I'll replace it with a 5% resistor. I mostly buy 5% resistors, but I have made exceptions on occasion to use 10% parts to replace 10% or greater parts.
"Too far out or spec" is a matter of opinion. Many restorers keep anything within 20% of spec, but I am a little pickier. If a resistor is outside of 10%, I'll usually replace it. If it is a 5% part and out of spec I'll replace it with a 5% resistor. I mostly buy 5% resistors, but I have made exceptions on occasion to use 10% parts to replace 10% or greater parts.
John Honeycutt
