Yamaha 70hp charging problem

[greeny]

Hi, I'd appreciate a bit of help on a small problem with a friends engine if any one would be so kind.
He's got a 1998 yamaha 70hp 2 stroke outboard. The charging voltage starts at around 13-14 volts when the engine is started but then rises up to 17-18 volts after a few minutes and stays up there. I've checked the output with a meter and it's definitely up at 17 volts. I've also checked at the battery terminals and they are at 17 volts. The voltage coming out of the small rectifier package is also at 17 volts plus. The higher the revs the higher the voltage goes.
This looks like the regulator has gone to me but when I look at the drawings that came with the engine there is no regulator listed, it just shows a rectifier. Looked on the engine and that is what is there, a small encapsulated pack with 2 green wires going in that come from the "charging coils", a black ground wire and the red wire out to the live bus for the engine. When I look at drawings for other engines of that era they all list the small unit as being a rectifier/ regulator and the units are slightly larger, but on the drawing for the 70hp it just calls it a rectifier.

Just wondering if anyone else has had this problem. I don't want to change the "rectifier" if that is not the cause of the problem. The dealer down here in Portugal just wants to sell me the small rectifier block but if it's only a rectifier then it won't solve the problem and cost him over a 100 euro for nothing.
The other question is if this block is only a rectifier then where is the regulation done, I can't find any reference to a seperate regulator.

Greeny

 

[jfm]

It is not a rectifier only. It is a combined regulator and rectifier in a single component. See part 10 on this page, which is specific to 1998 70hp 2T engine. Less than €100 too! http://www.boats.net/parts/search/Yamaha/Outboard/1998/70TLRW/ELECTRICAL 1/parts.html

 

[greeny]

Thanks

It is not a rectifier only. It is a combined regulator and rectifier in a single component. See part 10 on this page, which is specific to 1998 70hp 2T engine. Less than €100 too! http://www.boats.net/parts/search/Yamaha/Outboard/1998/70TLRW/ELECTRICAL 1/parts.html

Hi JFM
Thanks for clarifying that. I've downloaded that page before and seen it listed as a rectifier/regulator but the one actually on the engine is smaller than the one pictured on that parts list and smaller than the one that is pictured on a workshop manual I also downloaded.

The paper manual that supposedly came with the boat for that engine lists it as a rectifier only and the drawing in the manual is physically the same size and shape as the unit actually on the engine.

So .... do I ignore the paper manual, assume that the wrong unit has been fitted at some time in its life and go ahead and order the larger unit and hope it works.
I don't see why it wouldn't if it will physically fit in the space.
Or do I keep searching for something that may not exist and may not improve matters if it is only a rectifier.

The price I mentioned (113 euros) was the price the Portuguese dealer quoted to supply a rectifier regulator for that engine, I've not got into the debate about the 2 different types with him yet. I'm not sure I could explain to him what I'm trying to say as I don't speak Portuguese and his English is limited.

Thanks for your help
David

 

[BartW]

when you measure 17V on the battery poles, the battery might be broke,
unless you have a Volt meter that measures the AC ripple on the DC Voltage

if that rectifier is small and old, it might be that it is just a rectifier, no regulator,
in that case, it could be that the output delivers DC with a big AC ripple, up to 17Volt...

I would test the engine with a new battery first,
and
disconnect the old battery, charge it with a domestiv batt. charger, and after charging, voltage should be at least 12,3V if less, battery is fault.