Johnson 235 Rectifier Going??

[dhym]

Just took out my 85 235 for the first time this season and every once in while the tach will stop working, when it stops working the voltage will drop from 15.5V to 13.5V and then when the tach starts again the voltage come back up. I have heard this could be the rectifier and that it was not uncommon for these to quit. Any help would be appriciated. Thanks

 

[jim_in_day]

Re: Johnson 235 Rectifier Going??

DHYM That sounds like you have a loose ground somewhere. I would take the hood off and look for a loose wire. Also you might want to gently shake wire bundles and see if the tach acts up. The other possibility is a dirty connector, but unless you have been plugging and unplugging connectors, I kind of doubt that. We do see cracked wires shorting also, and that is usually fairly obvious. One of the real experts will be along soon and offer advice, but thats where I would start

 

[dhym]

Re: Johnson 235 Rectifier Going??

TTT. Anyone else run into this. I have jiggled and played with the wires and no difference.

 

[Tom Scully]

Re: Johnson 235 Rectifier Going??

On that model the rectifier and regulator are in the same housing. The normal charging voltage should be around 13-14 volts depending on the state of the battery. 15.5v sounds a bit on the high side. Check connection points for corrision and make sure they are tight, including the battery connections. Since the tach gets its signal from the rectifier and your voltage is outside of the regulation range it sounds like you are correct, but:<br />The tach should work at 13.5volts. <br /><br />At what rpm is the voltage at 15.5v?

 

[dhym]

Re: Johnson 235 Rectifier Going??

Was running at about 4200 to 4800. The other thing that I noticed was the voltage was not always consistant at that RPM. Sometime 14.0 and other most of the time upto 15.5.

 

[Tom Scully]

Re: Johnson 235 Rectifier Going??

If all your connections are clean and tight, replace the rectifier/regulator.

 

[dhym]

Re: Johnson 235 Rectifier Going??

Since boat is at the lake (2hrs away) which rectifier/regulator is it? I look up the part on I boats and it comes up as the little one with three leads. I check on BRP website and it tells me it is the box c/w regulator/rectifier. We are talking $250 price diff.

 

[Tom Scully]

Re: Johnson 235 Rectifier Going??

Unfortunately I think it's the one from the BRP site. The small one with 3 wires is a rectifier only.

 

[gigreg2]

Re: Johnson 235 Rectifier Going??

I just went thru this. If I were you I would buy a stator also. Do it all at once. A bad rectifier/regulator can fry the stator it did it on my 200 hp johnson.

 

[byacey]

Re: Johnson 235 Rectifier Going??

Rectifiers either work or they don't, and the stator isn't likely to get damaged unless the rectifier is shorted. I would examine your wiring closely first before spending that much money. When you measured voltage differences at high engine RPM's, did you measure it right at the battery terminals? If one of the stator wires to the rectifier was loose or broken, it could exhibit this problem. I haven't seen the circuit for your particular motor, but most tachs are connected to the stator before the rectifier - they measure the frequency of the alternating current before the rectifier, so theoretically the tach should still work with the rectifier removed. Sounds like a bad connection between the stator and rectifier, or ground if the stator has a grounded winding.