PROXXON Metal detector repair. Loose wire from coil. - Page 1
Forum section: electronics / repair

author: carbono.silicio
author_rank: Contributor
timestamp: May 11, 2020, 10:15:42 pm
content: Hello all,I need help from someone that has a PROXXON Metal detector like the one in the photos, and if possible, can tell me where in the PCB is soldered the broken enameled red wire coming from the detector coil.Thank you very much!

author: cheeseit
author_rank: Regular Contributor
timestamp: May 12, 2020, 09:43:45 am
content: Don't have one and not sure I can help but could you post a better picture of the PCB, both top and bottom? Has the marking on the IC been removed?

author: carbono.silicio
author_rank: Contributor
timestamp: May 12, 2020, 11:50:59 am
content: Quote from: cheeseit on May 12, 2020, 09:43:45 amYes, here some better pictures.Markings are there but it seems that not all were originally done. Three of five connected wires do not have any marking, the other two have L2 and IN.Thank you

author: SparkyFX
author_rank: Frequent Contributor
timestamp: May 12, 2020, 02:30:53 pm
content: I think the one marked in yellow, because there is something in, but not populated from the top:

author: cheeseit
author_rank: Regular Contributor
timestamp: May 12, 2020, 02:58:08 pm
content: That would be my suggestion too.

author: Haenk
author_rank: Super Contributor
timestamp: May 12, 2020, 03:00:11 pm
content: I suspect that one as well. If you carefully remove the solder, a rest of the wire should be present. Or maybe push through the hole with a needle while heating up the solder - if the rest of a wire comes out - bingo.

author: carbono.silicio
author_rank: Contributor
timestamp: May 12, 2020, 04:48:45 pm
content: Quote from: SparkyFX on May 12, 2020, 02:30:53 pmYes I see your suspition (that small nipple in the solder) but unfortunatelly no, took all soldervcarefully out and no wire. Also it would be connected to the non inverting input of channel 4 of the 324 and is unpopulated so it's not used in the circuit.The length of the loose wire is short (unless it got broken in to parts) so it should be around R31, R4, C5, C6.Someone with the same tester would definatelly help here!Thank you all

author: SparkyFX
author_rank: Frequent Contributor
timestamp: May 12, 2020, 06:18:07 pm
content: Right, the output was not populated either.Assuming it is connected to one of the remaining inputs, there might be a missing connection at pin 6, maybe it was connected directly to that solder blob, without a pad for it.

author: cheeseit
author_rank: Regular Contributor
timestamp: May 12, 2020, 06:20:38 pm
content: Quote from: carbono.silicio on May 12, 2020, 04:48:45 pmI noted the short length too but couldn't see anything obvious nor figure what it might be around there. The remaining wire looks to be broken above the part where the enamel is cooked so a bit of it should remain where it was connected. Or, as you say, it broke into multiple pieces but that seems unlikely. Unless someone was in there before you?I'm afraid you have to wait till someone with the tester comes along or someone reverse engineers the thing.

author: mikerj
author_rank: Super Contributor
timestamp: May 12, 2020, 06:59:13 pm
content: Looks like the possible remnants of a broken wire in this solder joint on the underside

author: carbono.silicio
author_rank: Contributor
timestamp: May 12, 2020, 08:05:24 pm
content: Quote from: cheeseit on May 12, 2020, 06:20:38 pmUnlikelly but possible, this tester has many years given to me by an old carpenter...

author: carbono.silicio
author_rank: Contributor
timestamp: May 12, 2020, 08:07:27 pm
content: Quote from: mikerj on May 12, 2020, 06:59:13 pmYes you're right. I'll see it tomorrow.Thanks

author: carbono.silicio
author_rank: Contributor
timestamp: May 13, 2020, 11:28:29 am
content: Quote from: carbono.silicio on May 12, 2020, 08:07:27 pmYes it's the tip of the wire on the left. Ivve confirmed all solder suspected of having a broken wire but none seems to be it.