Blowing fuses - Where to buy them, and possibly how to solve?

ryanverbena

Hi all, 

I've recently picked up a Friedman DS40 and after only a few hours it's started blowing the fuse next to the power cable input (not sure of the name, maybe output fuse?). 

I've looked online and the consensus it a power tube or rectifier issue. Luckily I have spares for both so can troubleshoot this no problem, only thing is I don't have any fuses and I can't seem to find any suitable online. I live in London so I can possibly visit a store, but Maplin is now closed down so not sure where to look.

I need a T250mV fuse (pictured below). 

Further to this, I'm kind of hoping that it is a blown valve - but just so I'm aware, could it be anything else? I've tried to power it up and blown two of these fuses in succession (without changing tubes). 

Really sucky way to spend a new amp day...

ryanverbena

Correction - I've just realised that I made a mistake replacing the fuse - it was a 1A 250v fuse that was originally in the amp. Explains why the second one went instantly. 

I've just found a 10 pack on Amazon, will be arriving tomorrow.

Still doesn't explain why the first fuse went, but hopefully it is one of the above-mentioned tubes. The amp was in transit from prior to this so hoping that is the culprit. 

ICBM

It will be the rectifier valve (GZ34) most likely. Power valves tend to blow the HT fuse - in the round screw holder - instead.

The GZ34 is a poor-quality one anyway, I would replace it with a JJ before you waste more fuses on it!

Danny1969

Don't forget to order the T version ... which is time delay so won't blow with a very short surge 

JonSnell

https://uk.rs-online.com/web/p/cartridge-fuses/0563605/Buy from a reputable supplier, saves using Chinesium out of spec fuses.

ryanverbena

Thank you all, hoping that it is just the rectifier. I have ordered some more of the fuses that were suggested, cheers @Danny1969 ; & @JonSnell . 

And thanks John @ICBM ; for the advice on the rectifier - it was actually already a JJ GZ34, which I've moved out for the one below, purchased from Watford Valves a while back and never got around to using. I also swapped the power tubes for the stock TAD's that came with my Two Rock (happily swapped for the Jan Philips you recommended). Just waiting on the fuse now and hopefully should all work together, but nonetheless will try each one by one to single out the culprit. 

ryanverbena

New fuses just came and turns out it was the rectifier tube, best case scenario for sure. What an amp though... I owned a Runt 20 and a PT20 and this one is one another level. I know get the hype around Friedman amps.