Part Reference Designators

Layout
1

I am having a problem with parts reference designators. For example, I have to keep the connectors labeled the same as on an older version of the board that has been in production for years. For example, the old boards have TB1, TB1A, TB1B, TB2, TB3, TB4, TB5, TB6, TB7, TB8 and TB9. TB7 and TB8 are actually on option boards that plug onto the main board.

My problem is with the TB1A and TB1B designators. They are NOT the same part and I don’t want them linked in any way. If I go into the schematic and put TB1A and TB1B on the connectors, it wants me to add a 1 or 2 after that (TB1A?) . I don’t want that.

The only way I have found around it is to simply put the correct designators on the PCB on the Silkscreen layers in graphic Text and hide the Reference Designator text when plotting.

However, that is really confusing because now when I look at the schematic none of the parts references match what the PCB artwork shows! I currently have all of them referenced in order on the schematic… TB1 through whatever number without any letters, so TB1A is TB2 on the schematic, TB1B is TB3 and that throws off all the other TB? numbers that show up on the PCB and our old schematics.

I can explain why we have those two oddball designations… On the very original PCB we only had one connector TB1 that encompassed the connectors that are now TB1A and TB1B. At some point, we split that connector up for UL reasons and it became three separated connectors, but all our service guys thought of it all as TB1 and that is what all of our electrical drawings showed, so we just added the TB1A and TB1B on the two new connectors.

I wish we had never used A and B on those two connectors but we did and now I am trying to find out how to deal with them. Any Ideas?

Thanks

2

The designator has to end in a number.
As you have found you can hide the designator and replace with text on the silkscreen. I would also put the same text next to the connector on the schematic to show which ones are assigned to which text labels.

3

Maybe for the purpose of the netlist you could rename T1A and T1B as T14 and T18 but label them T1A and T1B with text? Then the other Ts can keep the same numbers.

4

Thanks, that is a something I had not thought of… That might work. Fortunately, I think that this is the only time we ever used letters on our boards for part numbers, so this should not be an issue with our other boards, thank goodness!

Actually, I could also name them TB1, TB11 and TB12. That seems logical to me… kind of like TB1-1 and TB1-2 .

5

Thanks, Yes, I need to mark the schematics so I don’t get totally confused. Fortunately this is the only time we ever used letters for part numbers so I won’t have this problem again.

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