Unknown Symbol

[guitarelecdude]

Hi I'm new to the forum. I was looking at a schematic and saw a symbol of a resistor with a circle around. Above it it says TR1. If someone could tell me what this is it would be great!

 

[guitarelecdude]

Here is schematic https://www.electro-tech-online.com/custompdfs/2011/06/5150evh.pdf

 

[DerStrom8]

Hi, guitarelecdude! Welcome to ETO!

My guess would be that it is a thermal resistor. What kind of circuit is it in? An image would be very helpful in this case.

Der Strom

 

[crutschow]

It could be a thermistor.

 

[guitarelecdude]

its in a power supply with an AC voltage coming in after a switch

 

[guitarelecdude]

its not a fuse because the fuse is before the switch

 

[KeepItSimpleStupid]

It's one of these: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=490-3960-ND

Call it an "Inrush current limiter", or NTC (Negative Temperature Coefficient) Thermister or "Thermal resistor"

When cold, the device has a higher resistance than warm. They are selected based on expected current.

Many moons ago, I remember them being called "Globar Resistors" and they were found exclusively in the degausing circuits of Color TV's. They were a common component at the Electronics Store.

 

[guitarelecdude]

Ok thanks, that makes good sense

 

[guitarelecdude]

I have another question if you're willing. Also on the schematic there are spots where the line stops at a dot and says some number with a "j" in front of it, for instance, "j46" I looked all over the schematic and cannot find where they are supposed to connect. I don't get it.

 

[KeepItSimpleStupid]

This one may be harder.

J could stand for Jumper.

J46 can also refer to Jack 46. This would mate with P46

It may also refer to a Test Point, J46 is just a signal on the board that needs to identified for probing. Usually they are labeled TP1 etc. though.

 

[guitarelecdude]

The dots come to about the middle of the board then line up across from each other but each number is not numerically a system.

 

[KeepItSimpleStupid]

My best guess is a Test Point. Post a pic of the board. if you just joined, it may take 24 hours or so and links could be stuck in moderation. Use go advanced/manage attachments.

 

[guitarelecdude]

Yeah I posted link so it must not have come through yet.

 

[guitarelecdude]

Yeah I posted link so it must not have come through yet.

 

[guitarelecdude]

It just came up on first page of this forum

 

[DerStrom8]

They look like female connectors, if you ask me. The wires terminate in a rectangular-shape, probably signifying the position of an external connector.
Der Strom

 

[KeepItSimpleStupid]

Yep wierd. Non standard. They appear to refer to "breakaway" portions of the circuit. They may have been created to keep some PCB design rules happy. Nonetheless, they mate with -1 or +1 of the designation. P and J may have made more sense, but they might be just wires.

 

[guitarelecdude]

Ok thanks