Help Identifying a Component

[RogerS7642]

I wonder if someone can help. I need to replace this component from an amplifier that dates back to around 1960. I assume that it is a resistor and when I put an ohmmeter on it I get a wide range of values but readings of about 1-4 megohms are the most common. Although the end has broken off it, very little is missing, I believe that it has only three color bands, white, yellow and silver.

 

[ChosunOne]

Assuming it has a common value, I think it has to be a 390KΩ resistor, +/- 20%. Can't really tell its size without something for scale, but I'd guess it's 1/4 Watt. I'd replace it with 390KΩ +/-10%(gold band instead of silver), 1/2 Watt (slightly larger) to be sure. Resistors are cheap and overkill doesn't cost much.

 

[ramussons]

A photo of the PCB and the location of the component will give us some idea of what it could be.

It could be a Diode, Capacitor.......

 

[shrtrnd]

I second ChosunOne's opinion.
My additional input is that resistors don't burn-up by themselves.
I'd be back-tracing that circuit and find-out what other component in there is damaged, that caused that resistor to overheat,
otherwise you're going to be looking to replace your replaced resistor again in the near future.
Good luck.

 

[RogerS7642]

The resistor (assuming that is what it is) was on the back side of the circuit board. I don't think it burned. I think it failed because of physical damage. But this amplifier has not worked for the last 50+ years. I know that it hasn't been powered up in that time. One of he transistors was physically damaged. The rest of the board looks OK but who knows what deterioration a half-century will cause?

 

[kpatz]

At that age especially unused it's probably in need of new electrolytic capacitors as well.

Being from 1960 you may be able to find a schematic or service manual online. That would help identify the component, its value, and its purpose.

 

[RogerS7642]

There is no manufacturer name to be seen on the board; so I drew a schematic myself (attached). Any further assistance will be much appreciated.

 

[bertus]

Hello,

Looking at the schematic, it is a feedback resistor.
The value of 390k suggested by @ChosunOne could well be correct.

Bertus

 

[ChosunOne]

Correction: My earlier post was off the top of my head and in the wee hours of the morning, and I didn't think to check before posting. Don't know what I was thinking, but a silver band on the end of your disintegrating resistor indicates a +/- 10% tolerance, not 20%; and a gold band would be a +/-5% tolerance. I know the other guys must have caught that; I guess they were just being nice, not to embarrass me.

 

[bertus]

Hello,

@ChosunOne , You are correct.
No tolerance band is 20 %
Silver is 10 %
Gold is 5 %

See also here :
Electronics color code

Bertus