Some Safety Warnings

Transcription

1 Sme Safety Warnings 1. With the pwer supply pen and cnnected t AC mains (huse) pwer, there is the pssibility that yu may cntact AC mains (huse) vltage. Depending n the scenari, that can be fatal. 2. The large aluminium electrlytic filter capacitrs are cnsidered hazardus, because f the cmbinatin f high vltage and high charge. Yu need t 'treat them with respect'. When yu remve AC mains (huse) pwer frm the pwer supply, these filter capacitrs take time t discharge. T gauge discharge status, a vltmeter can be used t measure the vltage n the filter capacitrs. Fr infrmatin n manually discharging the filter capacitrs, see discharge.html 3. In ld pwer supplies, the thermal paste used between semicnductrs and heatsinks, typically cntained beryllium xide (BeO). Beryllium xide is knwn t be carcingenic.

2 Cnverting newer mdel IBM 5150 Pwer Supply frm 120V t 240V Based n the guide by Paul Axfrd fr an lder mdel pwer supply: 20Pwer%20Supply%20t%20230%20VAC.pdf Guide by Mntech PCs. N warranty whatsever. Use at yur wn risk. This is fr a wrking 5150 pwer supply, that wrks n 110V (using yur step-dwn transfrmer), with a 12VDC fan, and a PCB that lks like the fllwing: Parts needed: Part Qty Digikey P/N LCSC P/N Jaycar P/N 10Ω 5W Resistr 1 A129454CT C RR K 1W Resistr 12 1KWCT C61312 RR K 1/4W Resistr 1 13KQBK C RR K 1W Resistr 1 33KWCT C70845 RR K 1W Resistr 3 100KWCT C RR K 1W Resistr 2 220KWCT C69875 RR K 1W Resistr 1 PPC560KW-1CT n/a RR nF 275VAC+ X2 capacitr with 15 r 20mm pitch 2 P14779 C RG N5408 Dide 2 1N5408DICT C36138 ZR-1018 SPST Relay w/ 12VDC cil & 250V 5A+ cntacts 1 Z8454 C SY A Slw-blw 3AG Fuse C SF-2226 High-temp silicne wire 1m n/a n/a The 13K resistr can be made up f tw r mre cmmn values sldered tgether in sme heatshrink tubing, such as 12K + 1K (as seen n the schematic), r 10K + 1K + 1K + 1K. The high-temp silicne wire is ptinal, but makes things easier, as yu can safely let the flexible wire tuch heatsinks.

3 Tls needed: Standard electrnics repair equipment. This is nt a beginner s prject. D nt attempt if yu dn t knw the basics, r dn t knw hw t stay safe arund high vltage. Trx T10H security screwdriver 1/4 nut driver 3.5 HDD t use as dummy lad Prcedure (in n rder): Replace the main 2A slw-blw fuse n the EMI filter bard, with a 1A slwblw fuse. Replace the tw 100nF X2 film capacitrs with 275VAC+ versins. Replace the 300K resistr n the EMI filter bard with a 560K 1W. Remve the fllwing parts frm the main PCB: R1 (2Ω 10W) (keep the psts) R5 (100K) R6 (100K) R7 (100K) R8 (100K) R66 (100K) R67 (100K) R71 (470Ω) R72 (470Ω) R73 (470Ω) R74 (470Ω) R75 (470Ω) R46 (470Ω) R47 (470Ω) R48 (470Ω) R65 (470Ω) R68 (470Ω) R78 (470Ω) R79 (470Ω)

4 Cut three traces as shwn belw Install tw 220K 1W resistrs as shwn belw, flat against the bard Install three 100K 1W resistrs at R6, R8, R67. Install twelve 1K 1W resistrs where the 470Ω nes yu remved were. Install a 10Ω 5W resistr at R1, reusing the metal psts. Install a 13K resistr frm HV-Grund t the leg f R79 clsest t C10. I tk HV-GND frm an unused hle meant fr a larger capacitr size, as seen here:

5 If yur relay is small enugh t fit there, clean the PCB at the empty spt next t the fan cnnectr, and glue the relay there with cyanacrylate, with cnnectins facing up. If it s t big t sit flat in that empty area, find anther way f safely munting it. Cnnect the relay cil terminals t the fan cnnectr. Rather than cnnect directly t the fan cnnectr, find tw cmpnent leads that cnnect t the fan cnnectr t slder t. I used jumper W23, and resistr R62 (the lead clsest t the fan cnnectr). Cnnect the relay cntacts acrss R1 with wires. Cnnect a wire frm R69(lead farthest frm AC-In cnnectr (J3)) t R7(empty hle at edge f bard).

6 Install a 1N5408 dide between R1(lead far frm AC-In (J3)) and HV-Grund, with stripe facing R1. I tk the HV-Grund cnnectin frm the lead f R13 that is at the edge f the PCB. Install a 1N5408 dide between R66(empty hle at edge f bard) and R1(lead far frm AC-In (J3)), with stripe facing R7. Install a 33K 1W resistr between R5(empty hle clsest t large capacitrs, NOT at edge f bard) and HV- Grund. Use the same HV-Grund cnnectin as the first dide yu installed. Cnnect a wire frm jumper W26, t R5(empty hle at edge f bard). The steps frm this page and the previus, shuld equate t smething like the fllwing: Test that arund 22VDC is between IC1-Pin1 and IC1-Pin12. Test that C1 and C2 bth have under 180V acrss them, as they re rated fr 200V max (mine were gd, at 164V and 167V), and they shuld be within 10V f each ther. They shuld bth add up t between 300 and 350V, depending n yur line vltage (mine was 331V with exactly 240V line vltage). Test PSU utput vltages. Dne! Enjy.