M3 manual wiring test

[geldo79]

Hi,

Stupid question. I removed the upper manual from an m3 for installing foldback. When I desoldered the wires from the terminal, i was not so shure if the wires were really soldered exactly the same way as they were separated by the tape around the wiring loom. I can try of course when i reassemble the manual. But is there a way to test for the correct wire? When i try it with a digital multimeter (connecting one end to a terminal, the other end to the tone generator where the wires are soldered to), i get continuity for each connection to the tone generator (i guess because of low impedance system?).

Greetings Christian

[Jaim]

If you look at the schematic, measuring the resistance on the TWG to ground will always show a connection through the pickup rods or filter. The matching transformer which is connected to the buss bars also has a low impedance reading to ground. If you are reading a resistance from a upper manual terminal to all TWG connections with no keys depressed, then it appears you may have a cypher. What happens when you set the draw bars to 0?

Edit - Even with the draw bar at 0 - there is still a path to ground. I've done 3 fold back mods and use a tone generator to a small amp to check the wiring.

Jim

[enor]

The harness _is_ laced correctly though - if you put it back on according to the lacing it will match.

[David Anderson]

Whenever you disassemble something you've never disassembled before, carefully document everything you do, and take digital photos. One good digital photo can save you a lot of grief when you can't remember what goes where.

[geldo79]

Thanks for your hints. Thought it wouldn't be necessary to take photos here, because of the lacing....which seems to be in good condition ( see image ). But as i said, when i desoldered the wires i was wondering if the they were not always soldered corresponding to the lacing.

[enor]

Yes they are.

[geldo79]

It worked :-> I am enjoying the full foldback and manual tapering on my upper manual now.

[tpappano]

Looks great, nIce job!