Unknown Resistor value?

[Duke58]

The large resistor on the left has 5 bands. Looks like yellow, violet, orange, white and a blue band to me- but that would mean it's a 47 giga ohm resistor?

I know that isn't right...

It's from the HV power supply in a Tektronix 575 curve tracer. Can someone help?

Thanks!

 

[DF96]

Yellow, violet, orange would be 47k. 'White' might actually be silver - 10% tolerance? I don't know what the blue band indicates.

Alternatively, yellow violet orange silver could be 473 x 0.01 = 4.73 - I still don't know what the blue means.

Have you tried measuring it?

 

[Bill_P]

47000pF 600V 10% capacitor.
blue=600V

 

[audiopro]

Are you sure that is a resistor? Looks like a capacitor.

 

[Duke58]

Thanks guys!

Yes, it's a resistor. The caps that look the same are marked with the capacitance and voltage.

I think it's R805, a 470k, 1/2 Watt resistor:

 

[scottjoplin]

The caps that look the same are marked with the capacitance and voltage.

Which would imply it's most likely a capacitor? Have you measured it?

 

[Duke58]

Here's a photo of the failed resistor or capacitor:

 

[Duke58]

It shows open (OL) on the DMM.

 

[Enzo]

That is not a 1/2 watt resistor by any means, and the color code is 47k, not 470k. It is a 0.047uf cap. (47000pf)

These were very common back in the day.

 

[radtech]

That's definitely a capacitor. Molded paper, 0.047uF 600V 10%. Commonly known as 'bumble bee' capacitors in the guitar amp business, usually made by Sprague.

Looks like maybe C811 in the power supply? Trace the circuit to see where it's connected.

 

[daqvin_carter]

That really looks like a capacitor. If you can draw enough of a schematic as as as that part and other resistors, we should be more sure of the value.
Also check this https://www.google.com/url?sa=t&rct...5_manual.pdf&usg=AOvVaw0Zp9sFCisYDWJGUj_vfYGe

 

[Bill_P]

Here is the databook table specifying the color code for your capacitor.

 

[Duke58]

Thank you all for the replies.

It is indeed a paper capacitor- C811 on the schematic, a 0.047 uF, 600V capacitor.

Good thing I didn't replace it with a resistor! I would have had a boat anchor curve tracer.

Again, thank you all for setting me straight!

 

[Duke58]

Tektronix did an excellent job with their documentation, you can tell what circuit by the component number (anything with an 800 number is for the CRT section, for example), each section is marked on the curve tracer, the tubes are all marked. The manual has a calibration and troubleshooting procedure. I wish Tektronix made audio gear!

 

[Duke58]

Here's another cap that I can't tell what value: (Located near T601)

I see Red, red, orange, white, blue. My wife and son say it's orange, red, orange, white, blue.

After 60 years on the machine, it's difficult for me to see what colors the bands are so I can replace it. It measure 32 nF on my Fluke multimeter.

Any help is appreciated...

 

[Duke58]

As a sanity check, I'm reading it as a 0.022uF, 600V cap.

 

[Bill_P]

As a sanity check, I'm reading it as a 0.022uF, 600V cap.

That looks right. Are you using the Tek 575 manual that was linked previously to help identify parts? This one looks like C816.

 

[Duke58]

Yes sir, I am using the manual and agree that it is C816.

Thank you for verifying.