Chassr 1 #1 Posted March 13, 2022 where do I start to find a no charge problem with this 1990 520H I have had it since new 1200 hrs has had an electrical fire installed new rectifier it shows that it puts out a charge but its not showing on gauge and not charging battery Share this post Link to post Share on other sites
peter lena 8,038 #2 Posted March 13, 2022 @Chassr might try adding grounding to that rectifier tin mount area , just a connection from battery ground bolt point . any corrosion in those tin mount bolts , will affect its conductivity , often use small alligator clips on 12-14 gage wire to test a power run . dielectric grease on bolt threading to area . just a suggestion , pete Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,488 #3 Posted March 13, 2022 Welcome to the forum. Download this file. One page shows the charging circuit. The wire colors at the engine may not be correct. Look for overheating at the 9-pin connector and yellow wire. Share this post Link to post Share on other sites
peter lena 8,038 #5 Posted March 13, 2022 @gwest_ca agree with the overheating connector area , often has an electrical plastic cracking dust in the area . might also be a good time to do a wire strain reroute , typically related wires are hard dried and cracked , giving related wiring issues. only a suggestion , pete Share this post Link to post Share on other sites
lynnmor 6,762 #6 Posted March 13, 2022 Download the Onan Service Manual here. With it you can troubleshoot the charging system. The remainder of the wiring can be checked using the previous mentioned Demystification Guide mentioned above. Share this post Link to post Share on other sites
Chassr 1 #7 Posted April 18, 2022 thanks all for the re On 3/13/2022 at 2:55 PM, lynnmor said: Download the Onan Service Manual here. With it you can troubleshoot the charging system. The remainder of the wiring can be checked using the previous mentioned Demystification Guide mentioned above. Share this post Link to post Share on other sites
Chassr 1 #8 Posted April 18, 2022 Thanks all for the reply I work away and not home to keep at this could someone tell me if I can run a wire straight from charge side of rectifier to battery thanks Share this post Link to post Share on other sites
lynnmor 6,762 #9 Posted April 18, 2022 1 hour ago, Chassr said: Thanks all for the reply I work away and not home to keep at this could someone tell me if I can run a wire straight from charge side of rectifier to battery thanks Yes you can. Share this post Link to post Share on other sites
cleat 4,936 #10 Posted April 19, 2022 That is how the early 520's were wired basically (they ran a wire to the solenoid). Just be sure to put in a 30A inline fuse for safety. Share this post Link to post Share on other sites
Chassr 1 #11 Posted May 15, 2022 thanks all charging again did use 30 amp fuse charge does cycle to trickle seems normal probably cruel to ask an older tractor like this to cut 3 acres but it does effortlessly also what oil filter would be right for 20 hp Onan thanks 1 Share this post Link to post Share on other sites
lynnmor 6,762 #12 Posted May 15, 2022 3 minutes ago, Chassr said: what oil filter would be right for 20 hp Onan thanks Use an Onan 122-0800 or Fleetguard Lf3339 oil filter. Be sure that you have a 122-0502 Oil Filter to Shroud Gasket installed. Share this post Link to post Share on other sites
