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| Xantrex/Sorensen XHR 40-25 schematic? |
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| ifonlyeverything:
C151 and C239 were tantalum, replaced both with ceramics from my eBay TH ceramic kit. The others I replaced were electrolytics. |
| ifonlyeverything:
The problem of a buzzing transformer and fluctuating output voltage is back -- except this time the linear regulators are still working fine! Applying pressure to the top of the unit apparently causes this problem. It looks like this flexes the super shitty IDC box headers they used to join the A2 and A3 PCB. I can't easily Ohm this out so I guess I'll just replace it. The PCBs all have thick insulating paper underneath and they definitely are not cracked, so I don't think it's mechanical pressure inducing a short or open circuit or anything like that. |
| coppercone2:
yeah xanatrax sorenesn IDC breaks I seen it pop out before but that is a cold welded cable (it cold welds the wire to the fork via the crimp tool), its like a crimp spot weld. some people touch it up with solder but it might be difficult the bond area for those IDC cables is basically the area of two prongs of a sheet metal fork (the thin inside part of the fork, like between fingers (bronze I think, maybe steel), once it goes it goes just reseating the wires with a screw drivers is a temporary solution, your not remaking the cold weld. its the same technology as this https://telcodepot.com/premium-punchdown-tool-1328 |
| ifonlyeverything:
--- Quote from: coppercone2 on May 04, 2024, 07:28:23 pm ---yeah xanatrax sorenesn IDC breaks I seen it pop out before but that is a cold welded cable (it cold welds the wire to the fork via the crimp tool), its like a crimp spot weld. some people touch it up with solder but it might be difficult the bond area for those IDC cables is basically the area of two prongs of a sheet metal fork (the thin inside part of the fork, like between fingers (bronze I think, maybe steel), once it goes it goes just reseating the wires with a screw drivers is a temporary solution, your not remaking the cold weld. its the same technology as this https://telcodepot.com/premium-punchdown-tool-1328 --- End quote --- The A2-A3 board connection is done with a box header to box header connection -- there is no IDC cable. Anyways, I was targeting the wrong area. It was the damn tab-mount snubber on the diode being slightly bent, just enough to ever so slightly contact the case of the power supply when mechanical pressure was applied! :palm: I bent it downward, toward the PCB, and the problem is now gone. Now to get some Nichrome wire for a load test and to figure out how to trim out the error between CV and measured output voltage. The error is 0.1V for CV <9V; 1.2V for CV of ~24V; and 0.6V for CV of 36V. So that is definitely strange. |
| coppercone2:
well that cable is insulation displacement (IDC) did you see how the crimps are made? Not sure if it works exactly like a MTA crimp (individual press in), but it does cut through ribbon cable insulation. you don't strip that there is a tiny fork that cuts the insulation and then I assume cold welds itself to the wire in a tiny point pressure point. to make those cables you just lay it in unstripped... I never saw a soldered version of it in any test equipment, definately not in any xantrax or sorensen I worked on (numerous) |
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