Failed Diode board replacement

[endo85]

Hi everyone,

I've a 1995 R100R which suddenly developed unreliable starting with the starter barely turning over. Load tested battery, checked connections, grounds etc and eventually found one of the large diodes was open circuit on the main diode board.

Rather than replacing with the same OEM part I've looked at more modern alternatives, most of which are combined rectifier/regulators.

I'm not necessarily looking to have one that's Lithium compatible. I've been looking at RR45 by Electrex in the UK, but it's quite a big unit (110x80x30mm). I think if I remove the two upper rubber mounted bolts for the original diode board and fit the new unit on the remaining two bolts (perhaps with a smaller spacer) I think there'll be enough room behind the front cover.

Although the manufacturer has not made any recommendations about placement, I would rather fit outside of the engine casings away from heat but there's no obvious room to fit this on the top of the frame.

Has anyone fitted an Electrex, or fitted and can recommend another unit, or has any recommendations?

Many thanks in advance.

[Rob Frankham]

Personally, I wouldn't move away from the original... after all assuming the failed one is the original, it's lasted 28 years and there is no guarantee that a 'more modern' non OEM board will be more reliable. That being said, if it's a recifier/regulator, will it fit in the space vacated by the original... Outside the engine casing in an airflow is always good for high current handling electronics.

Rob

[SteveD]

I've used a thunderchild diode board for decades. A worthy alternative, but the oem are also good.

[RPGR90s]

Stay with the oem style at least. As SteveD points out, the Thunderchild is an excellent replacement. I've had one on my R90s for twenty years with zero issues.

[endo85]

Thanks all for your replies and advice. Much appreciated.

[endo85]

After reading everyone's feedback and looking at all the available options, I've opted for the Thunderchild rectifier. It appears to be an improved design but fits with no re-wiring or different mounting needed.

I must mention that support from John at Thunderchild was outstanding. I happened to mention that I was going to replace the cable that goes from "Y" on the stator to an L spade connector to the diode board, as the spade connector had some internal corrosion. He offered to make one up and ship it with the diode board!