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Reply To: GV650 FI 2002 – REGULATOR / RECTIFIER Instant overheat

Mar 5, 2026 at 8:43 PM #22073

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Topics: 1
Replies: 4

🌍 Country: Germany
⚡ Bike Model: 2010 GV650 Aquila FI

The channel layout for all images below is the same:
CH A – Probe on Y1 wire from the Stator uses a 20:1 attenuator
CH B – Probe on RR DC + output
CH C – Probe on RR DC – output (BW wire), with the probe ground reference clipped to battery negative. Since both the BW wire and the probe reference connect to the same point (battery negative), this channel essentially measures the voltage drop across the ground return path.
CH D – Probe on Bat Positive Terminal

All probe ground references use the same batter negative clip to provide the exact same ground reference wire path for all channels.

Below is the wavefrom of my initial test, u can clearly see the weird drops and spikes, the RR DC output voltage drops towards 0V at the same time the ground resistance seems to jump up as, this also cuts the stator phase short.

Now the exact same probe setup above but this time with my own DC return path aka the described own positive and negative wire with a fuse directly to battery.

To note here is the ground resistance is much lower and also as this was a bit after the first test the battery has a higher voltage.

Now this waveform below is a reference i used as at some point i was thinking maybe this is just how the RR cuts off and its normal, as i dont have atm any similar bike to the engine type of the hyosung bike i could only do the exact same setup on a CBR600RR 2003 so below is the waveform for that and this does not have those massive drops of voltage and yes i know this is not a good comparison to hyosung engine type but it uses the same charge system with a shunt RR.

Also to note here is no matter how hot the RR was even when it was boiling hot like oem hyosung RR that broke it never stopped charging it always charged and never had that failure point i am experiencing on the hyosung where it just stops charging and either shorts out like the oem one or recovers after cooling off. It always worked at idle and high rpm.

Now also i also run the setup of test 1 until the failure event once, and got this waveform after it stopped charging.

To note on the post-failure waveform, after the R/R thermally fails and stops charging, the behavior is strange. It’s unlikely this R/R has any built-in thermal protection to shut down gracefully. If it had truly shut down completely, all SCRs would be fully fired and the stator phase on Channel A should show a flat line at ~1.5-2V just the forward voltage drop of two diodes routing current straight back to the stator. But that’s not what I see. Channel A still shows 14.4V rectangular waves as if the R/R is actively regulating at ~50% SCR duty. Yet the R/R DC positive output reads only 12.86V while the battery sits at 12.93V meaning the battery is actually at a higher voltage than the R/R output, so zero charging current can flow. The math doesn’t add up either: a 14.4V stator peak minus ~1.4V across two diode drops should yield around 13.0V at the DC output, not 12.86V. Something inside this R/R is clearly not functioning correctly after thermal failure it’s neither fully shutting down nor properly charging, it’s stuck in a broken state where it wastes stator energy through partial SCR firing while simultaneously failing to deliver any power to the battery.