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Is That Reading Right? Compare Your Meter With Known-Good Values for a Board
To judge a meter reading you need the value a working board shows on the same net. OpenBoardData is a community archive of those values for about 100 boards, mostly Apple. Our free board viewer shows them as you hover over a pin, and lists them for every net, with the conditions they were taken under.
You probe a rail and the meter says 0.39. Is that fine? On its own, the number says little. What you want is the value a working board shows on the same net.
That’s what OpenBoardData collects. It’s a community archive of known-good diode, voltage and resistance values, with diagnostic notes, for about 100 boards, mostly Apple. Repair people measure good boards and share the numbers.
Our free board viewer puts those numbers where you’re already looking.
How to use it
- Open your board file. If the board number is in the file’s name, as in
820-00165.brd, its data loads by itself. - No match? Pick the board from the list above the viewer. It remembers your choice for that file, in your browser. You can also turn the data off or change it if the match is wrong.
- Hover over a pin. The tooltip shows the net and its values, such as
D 0.390 · V 3.300. - Click it. Details shows every reading for the net, with the conditions it was taken under.
- Scan the Nets list. Each net shows its readings, so you can run down a list of rails while you probe.
Click a part and you also get its value and rating where the archive has them, such as 1UF, 6.3V.
To keep score as you go, type your own reading under the net. The viewer shows the plain difference, such as “0.012 higher than known-good 0.398 (3%)”. It doesn’t call it good or bad: that’s your judgment. Your readings stay in your browser.
Read the conditions
Two readings of one net can both be right. On the 820-00165, the phase nets have resistance readings listed separately for different CPU and memory versions of the board, and some readings were taken with a trackpad and keyboard installed. The viewer shows those conditions next to each value, so compare like with like.
Take the method into account too. People take diode readings with the probes either way round, and the board’s state matters. A reading a little off isn’t proof of a fault, and these are community numbers, so treat them as a guide.
The notes are links
The archive’s diagnostic notes open in the Repair tab. One for the 820-00165 backlight says to check the enable signal on U7701 pin 3 if the output is at 8.4V. In the viewer that pin is a link: click it and the board goes there, and if the schematic is open, that does too.
About the data
The viewer keeps a dated snapshot of the archive, so it works without calling their server from your browser. Your board file isn’t sent anywhere. Only the data file for your board is requested, from our site. The data remains the work of OpenBoardData’s contributors, under the Open Database License. To add your own readings, go to their site. The archive also works inside FlexBV, the desktop boardview program.
