Is White PCB Actually White?

[The Doktor]

I had been considering how to make replacement meter faces.  I have heard of people printing out face and attaching it with adhesive, but I have rather limited use of my hands and that would be an incredibly difficult thing for me to accomplish.

Why is it easier to attach a PCB than a piece of cardstock?

Limited use of hands. Very fiddly cutting out a label and getting it aligned on the old face, at least for me. Never thought of just using a piece of cardstock by itself, wonder how that will look? Still a bitch to cut it out, maybe get a friend to do that. I think I'll order some card stock...

[gnuarm]

Full scale is 600V 1mA.

This would be a 600 kohm meter coil resistance. 

How are you planning to generate the 600V to drive it full scale? 

Why did you not pick a meter with a lower full scale voltage?

The meters voltage (as delivered) is not important, and they didn't have any in low voltage ranges, out of stock. The coil is the same in all meters of this series, 1mA full scale and somewhere in the tens to hundreds of ohms resistance. There is a series resistor internally to give full scale reading at appropriate voltage. I'm in there changing the dial anyway, resistor is easy. I think I've got a 4.7K in there now, pegs a bit under 5V. Need a bit lower with ESP32.

Than it is not a 600V meter.  That is just what's on the face plate. 

[The Doktor]

Full scale is 600V 1mA.

This would be a 600 kohm meter coil resistance. 

How are you planning to generate the 600V to drive it full scale? 

Why did you not pick a meter with a lower full scale voltage?

The meters voltage (as delivered) is not important, and they didn't have any in low voltage ranges, out of stock. The coil is the same in all meters of this series, 1mA full scale and somewhere in the tens to hundreds of ohms resistance. There is a series resistor internally to give full scale reading at appropriate voltage. I'm in there changing the dial anyway, resistor is easy. I think I've got a 4.7K in there now, pegs a bit under 5V. Need a bit lower with ESP32.

Than it is not a 600V meter.  That is just what's on the face plate.

I don't think there are any 600V meter movements, correct me if I'm wrong. When you hook the wires up to the 2 terminals on the back, it indicates 600V. And you'll read 600K ohms across those terminals. 150K for the 150V meter, etc.

[gnuarm]

Full scale is 600V 1mA.

This would be a 600 kohm meter coil resistance. 

How are you planning to generate the 600V to drive it full scale? 

Why did you not pick a meter with a lower full scale voltage?

The meters voltage (as delivered) is not important, and they didn't have any in low voltage ranges, out of stock. The coil is the same in all meters of this series, 1mA full scale and somewhere in the tens to hundreds of ohms resistance. There is a series resistor internally to give full scale reading at appropriate voltage. I'm in there changing the dial anyway, resistor is easy. I think I've got a 4.7K in there now, pegs a bit under 5V. Need a bit lower with ESP32.

Than it is not a 600V meter.  That is just what's on the face plate.

I don't think there are any 600V meter movements, correct me if I'm wrong. When you hook the wires up to the 2 terminals on the back, it indicates 600V. And you'll read 600K ohms across those terminals. 150K for the 150V meter, etc.

The point is, I asked you about the full scale meter voltage and you said it was 600V.  Now you are saying its very low, maybe less than a volt. 

Ok, it will do what you want.  If it really is 1 mA full scale, just pick a resistor that will give you a full scale reading from the voltage you can drive with. 

[MarkS]

Have you considered just making a small PCB (1" x 1" or similar) with a do nothing circuit and have it manufactured in white? It would cost just a few dollars and you'd have a real example to review.

[jt]

As a point of caution about white soldermask - a company I worked at switched fabs and the "white" soldermask turned out with a definite pink hue.  I forget what their excuse was.  Wasn't really a problem, just not the aesthetic we were going for, especially given the PCB is visible in the end product

[mikeselectricstuff]

As a point of caution about white soldermask - a company I worked at switched fabs and the "white" soldermask turned out with a definite pink hue.  I forget what their excuse was.  Wasn't really a problem, just not the aesthetic we were going for, especially given the PCB is visible in the end product

Was it an ENIG finish by any chance ?
I've seen this - the plating process did something to the soldermask ink, turning it pink. We ended up getting the mask re-printed after plating - this was with a UK PCB place so we had the flexibility to do this.
There are also  different types of white soldermask with different opacity and print resolution.

[jt]

Was it an ENIG finish by any chance ?

Ah, yes, that was the root cause now that you mention it.  Thanks!