Sten Problems

A friend's AGM Sten did have a similar problem. It came down to the way the contacts had bent during use.

The switch is simply a pair of metal contacts. I suggest having a close look and you may find they're not connecting correctly. If they aren't then you should be able to carefully bend them back into shape.

Personally I have a VIVA sten , which uses a standard switch you can buy at any electronics shop... If/when something goes wrong with that it should be an easy thing to replace!

Could be a partially charged battery . Or that special clip in the stock that holds it together .

A friend's AGM Sten did have a similar problem. It came down to the way the contacts had bent during use.

The switch is simply a pair of metal contacts. I suggest having a close look and you may find they're not connecting correctly. If they aren't then you should be able to carefully bend them back into shape.

Personally I have a VIVA sten , which uses a standard switch you can buy at any electronics shop... If/when something goes wrong with that it should be an easy thing to replace!

Yes, I took a look at the contacts and they were a bit out of place after firing about 1000 rounds through it. I did bend them back into place and it is working much better but still not 100% of the time. Thanks for your help. Maybe I could try and put VIVA contacts in the gun instead.

Could be a partially charged battery . Or that special clip in the stock that holds it together .

Unfortunately no, I tried 3 different batteries that were all fully charged and it ended up being the trigger contacts. Thankyou anyway

Yes, I took a look at the contacts and they were a bit out of place after firing about 1000 rounds through it. I did bend them back into place and it is working much better but still not 100% of the time. Thanks for your help. Maybe I could try and put VIVA contacts in the gun instead.

Cool...

I don't think you'll get the viva mech in there. The trigger arrangement is completely different. The viva actually activates one of the small red push switches, just like this. http://www.nairnshire-modelling-supplie ... p-574.html

I did bend them back into place and it is working much better but still not 100% of the time. Thanks for your help. Maybe I could try and put VIVA contacts in the gun instead.

The contacts might need cleaning.
Because of the large current flowing in them, every time the contacts make, they arc a bit. That makes the contacts dirty, and could easily affect performance. The more often you pull the trigger, the more it happens. So if you keep firing short bursts, it's worse on the contacts than firing a whole mag at once. This holds true on any mechanical switch. The open contacts type can often be cleaned, but a closed one, as Yith describes is on the Viva, would need to be replaced.
MOSFET controllers reduce that arcing to the point it's insignificant by moving the high-current switching to a solid state device (the MOSFET), and reducing the trigger switch current to a few milliAmps, if that.

BTW, that switch Yith links to is only rated at 0.5A/125 VAC. That's not going to be more than 5 or 6A at lipo voltage, meaning it's switching far more current than it's made to.

I did bend them back into place and it is working much better but still not 100% of the time. Thanks for your help. Maybe I could try and put VIVA contacts in the gun instead.

The contacts might need cleaning.
Because of the large current flowing in them, every time the contacts make, they arc a bit. That makes the contacts dirty, and could easily affect performance. The more often you pull the trigger, the more it happens. So if you keep firing short bursts, it's worse on the contacts than firing a whole mag at once. This holds true on any mechanical switch. The open contacts type can often be cleaned, but a closed one, as Yith describes is on the Viva, would need to be replaced.
MOSFET controllers reduce that arcing to the point it's insignificant by moving the high-current switching to a solid state device (the MOSFET), and reducing the trigger switch current to a few milliAmps, if that.

BTW, that switch Yith links to is only rated at 0.5A/125 VAC. That's not going to be more than 5 or 6A at lipo voltage, meaning it's switching far more current than it's made to.

Thankyou very much for your help. I'll get inside there with some silicon oil in a bit. BTW rust builds up very quickly by the sea so I may need to lube that up every once in a while

Silicone oil won't help, and could make it worse.
On the contacts ONLY, contact cleaner, or a small amount of WD40 should be used and wiped off.
Acetone (nail varnish remover) or IPA (IsoPropyl Alcohol), or surgical spirit could also be used, but make sure not to get any of it ANYWHERE other than the contacts. There are some chemicals in there that love to eat rubber seals, etc.

What will also help is making sure the contacts make firmly. Switch contacts "bounce" when they touch, and each bounce is an arc. Firm, hard contact reduces the amount the contacts can bounce.

BTW, that switch Yith links to is only rated at 0.5A/125 VAC. That's not going to be more than 5 or 6A at lipo voltage, meaning it's switching far more current than it's made to.

Yes, you are quite right, and it concerned me a lot when I first saw it. However after a couple of years of use it's still going strong and has the advantage that a replacement is very easily available and very cheap! Also very easy to fit! If it had been a problem I would have mosfetted the gun, and I've not needed to so far.

Which I can't say for the custom shaped bits of copper that most AEG triggers have. It was a pain in the bum and quite expensive to replace the trigger contacts in my M14/Garand which had burned away almost completely.

Silicone oil won't help, and could make it worse.
On the contacts ONLY, contact cleaner, or a small amount of WD40 should be used and wiped off.
Acetone (nail varnish remover) or IPA (IsoPropyl Alcohol), or surgical spirit could also be used, but make sure not to get any of it ANYWHERE other than the contacts. There are some chemicals in there that love to eat rubber seals, etc.

What will also help is making sure the contacts make firmly. Switch contacts "bounce" when they touch, and each bounce is an arc. Firm, hard contact reduces the amount the contacts can bounce.

OK, I have some WD40 in my drawer. Ill make sure I am careful. THANKYOU SO MUCH because i was just about to use silicon!

Um... caution with the WD40. Slightly off topic, but I recently had a problem with the pickup switch on my guitar, because it had not been used for months, the switch had oxidised (or summat). I used WD40, but it didn't help. Took it back to the shop, and the guy took the switch apart and cleaned it with switch cleaner, and told me not to use WD40, because it didn't work in this situation. Don't know if that is relevant to this case, but that's what he said.

That's why I said to wipe it off.
You want to use it for its solvent properties to loosen and remove the muck, then remove the "protective" element (which can be insulating) by wiping it off.
Switch/contact cleaner uses an alcohol (like IPA) to do the solvent job, but then it evaporates away, leaving the contacts dry.

Besides, if WD40 is what he already has, it won't hurt to try it first.
e.g. I have IPA and WD40. I'd use the IPA.