Decoding transformer windings from schematics, need a bit of help! - Page 1
Forum section: electronics / repair

author: RayRay
author_rank: Frequent Contributor
timestamp: August 15, 2024, 10:49:30 pm
content: Hey guys.I'm trying to figure out the windings/coils of a custom made PCB transformer from the device's schematic (attached, T2) so I could do a basic resistance test, but it seems a bit confusing as it implies that it has 12 pins when it only has 11 (one side has 6 in a row, where the other has 5 with the first pin having a lot of space from the other 4). How would you interpret the schematic? (again, it's T2 in it) Thanks.

author: ledtester
author_rank: Super Contributor
timestamp: August 15, 2024, 10:57:51 pm
content: Quote from: RayRay on August 15, 2024, 10:49:30 pmIt's the pin positions that are numbered - not the actual physical pins. That is, you don't skip any pin numbers just because the physical pin isn't present.So there is another pin position where that first pin has a lot of space between it and the other 4.

author: IanB
author_rank: Super Contributor
timestamp: August 15, 2024, 11:03:42 pm
content: If I count the connections shown on the schematic, there seem to be 11 of them (6 on the left side, 5 on the right side).However, the numbering seems weird, with two connections labeled "1" and two connections labeled "11".So I don't know what's going on there.Have you got the PCB? Can you match up the pin positions to the PCB tracks and figure out what goes where?

author: boB
author_rank: Frequent Contributor
timestamp: August 15, 2024, 11:19:03 pm
content: Bobbins with non-equal pins on one side vs the other, like you have here is typical to count going round in a circle like an IC pin count.From what I have seen personally, pin 1 should be the 1 where those two clocking pins are non-uniformly spaced. The other side of the bobbin being uniform.You can verify this with your Ohm Meter I would think.boB

author: RayRay
author_rank: Frequent Contributor
timestamp: August 15, 2024, 11:23:52 pm
content: Still not sure what to make of it. Should I ignore the ones marked with a red X?Should I treat the numbers as the coils themselves (I.E pins 3-4 and pins 1-5 each being a coil?)And yeah, it's definitely odd that both 1 & 11 show up twice.Quote from: IanB on August 15, 2024, 11:03:42 pmOf course. And I've desoldered the said transformer for testing purposes.The first pin is indicated on on the PCB (it's on the side with the 5 pins, and it has considerable amount of spacing to the other 4)The side with the 6 pins is the one that goes to that dual cathode diode (ER1620CT)

author: IanB
author_rank: Super Contributor
timestamp: August 15, 2024, 11:31:35 pm
content: So, from the PCB tracks you know connections "9", "11,0" and "7" on the right. You also know "1" and "5" on the left. Presumably "3" and "4" are shorted? So all that's left are "1" and "6" on the left, and "11" and "12" on the right. If they are unconnected, do you care about them?

author: RayRay
author_rank: Frequent Contributor
timestamp: August 16, 2024, 12:00:59 am
content: My results arepins 1-6 (no connection, they're also marked with a red X on the schematic)pins 3-4 * 0.2 OHMspins 1-5 * no connectionpins 7-9-10-11 are suppose to be all connected, but got nothing between empins 7-10 * no connectionpins 10-11 * no connectionpins 11-9 * no connectionIf I properly interperted the schematics, I guess it means it's defective, but some confirmation would be welcome

author: ledtester
author_rank: Super Contributor
timestamp: August 16, 2024, 02:38:21 am
content: I believe the red X's just mean they are not connected to the PCB but there should still be a winding between 1 and 6 and between 11 and 12.Are you sure about the pinout of the transformer - ie how do you know which is pin 1?

author: m k
author_rank: Super Contributor
timestamp: August 16, 2024, 07:04:38 am
content: https://www.mikrocontroller.net/topic/441353