Replace unknown fuse on function generator

[rstor22]

I have a function generator (see attached specifications) where I need to replace the inline fuse on the output (see attached). After removing the inline fuse it has no markings and unfortunately the manual doesn't specify.

What rating inline fuse should I use for replacement? Should I choose fast blow or slow blow? Does the fuse need to be DC rated or is only an AC rated fuse fine?

Thank you

[Lightages]

Based on the fact that it can source >10V P-P at 50ohms, it is capable of outputting around 100mA at least. I would put in a 200mA fuse, fast blow. I would also install some kind of inline fuse holder rather than a soldered type. If you find you are blowing 200mA fuses too easily, up it to 250mA.

[mcinque]

Why not try the light bulb trick and if ok try to measure the "nominal" current and then calculate the fuse needed?

[rstor22]

Based on the fact that it can source >10V P-P at 50ohms, it is capable of outputting around 100mA at least. I would put in a 200mA fuse, fast blow. I would also install some kind of inline fuse holder rather than a soldered type. If you find you are blowing 200mA fuses too easily, up it to 250mA.

Thank you. I will try a fast blow 200mA fuse with an in line holder. Does it matter if the fuse is only AC rated?

Why not try the light bulb trick and if ok try to measure the "nominal" current and then calculate the fuse needed?

I'm not familiar with the light bulb trick, would you be able to provide details please.

[Lightages]

AC, DC, no real difference for your application.

[edavid]

Why not try the light bulb trick and if ok try to measure the "nominal" current and then calculate the fuse needed?

We are talking about a function generator output, not line voltage input 

[mcinque]

didn't read that you were talking of an OUTPUT. Nevermind.

[miguelvp]

According to this:

https://www.eevblog.com/forum/repair/semi-open-fuse/

It's a standard 200mA fuse

There is another repair thread:
https://www.eevblog.com/forum/repair/gw-instek-gfg-8020h-teardown-and-repair-(help)/

But doesn't specify the value of the output fuse, and it's hard to find any information of that fuse by searching for a gfg-8020h.

So a fast blow 200mA fuse might do the trick as Lightages suggested.

[SeanB]

Depending on how it is constructed a slow blow fuse will add a lot of inductance to the output, as they often use a spiral wound element. Fast blow is pretty much always just a straight piece of wire. Will not be an issue until you turn up the output frequency over a few kHz.

[electr_peter]

Fuse is there to protect FG output from short circuit. Just for reference, many ~10V FGs use 125mA fast type fuse.

[rstor22]

The Instek/Goodwill FG-8016G (which is the one I have)  appears to have also been branded under the name Elenco.

Elenco informed me of the following:

"The only info if found lists it as  a 100mA. I would use a standard 100mA 250VAC fast blow."

So it looks like the recommended fuses in this thread were in this range. Thanks everyone!