Odd issue with Cybergun Perun P90 (Carries on firing for a second or two after releasing trigger on full auto)

[Punisher3990]

Good evening all, 

Summary / Setup

I recently built and upgraded a CyberGun P90. Key specs: fitted with a Perun MOSFET (default settings, calibrated), running a Turnigy Nano-Tech 3S 1200 mAh 11.1 V LiPo (T-connector), and upgraded inner barrel / hop rubber / nub (ZCI barrel, Maple Leaf rubber).

Problem
When on full-auto, the gun fires normally when I press the trigger, but when I release the trigger it continues firing for 1–2 seconds before stopping. It feels like a delayed cut-off. Small bursts (short presses) behave normally; the problem only occurs if I hold the trigger for a few seconds. This is dangerous in skirmish use because the gun keeps firing after I’ve released the trigger.

What I’ve ruled out / notes

The behaviour is reminiscent of old triggerbar/contact stickiness, but this build uses a Perun MOSFET.

MOSFET is at default settings with calibration done.

Happens reliably on full auto after holding the trigger for several seconds; short bursts are usually fine.

I can supply a short video showing the issue if that helps — tell me what you’d like captured (angles, slow motion, closeups).

Thanks for your help

 

[Colin Allen]

Is the trigger returning quickly enough when released after longer bursts in FA?  I cannot think why it should do so, but...

Also, try reducing the Stage 2 trigger sensitivity to see if that affects it.

 

[Punisher3990]

I think so. It doesnt seem to be getting stuck or rubbing. 

I will try get a video of it tomorrow. Bit late to shoot it off right now but I will also try altering the settings you mention too. 

 

[Muzzer]

Im no expert but it is possible it could be a dirty or malfunctioning optical sensor. Quick test: put a 7.4 V battery on it and try again.

If the issue goes away then that kind of confirms it for me. But i would 100% clean the sensor with an appropriate cleaner, anyway.

 

[Punisher3990]

Thanks for the suggestion Muzzer, its possible I got some grime or fingerprints on the sensor when I was installing it. 

Following up from last night post i went to test it again this evening and the full auto was just shooting semi. I recalibrated it and now its full again but it seems odd that happened. 

Also noted that if i pull the trigger hard enough it does seem to get slightly stuck. Never noticed before because the full auto would kick in long before reaching that point. Worth noting this is only if I pull all the way back with a bit of force. It could just be me hitting the end of where it can go i guess? 

Unfortunatly I have neighbors so I can't really shoot alot this late which makes it hard to diagnose. Hopefully I can do some proper testing on Friday 

PS: this is a Cybergun p90 with a stock motor/gearbox