Laney VC30 HT fuse issues

[azatplayer]

Got a buddys VC30 on the bench, had a non working drive stage, open load R.
Easy enough fix. he had asked me to mod the thing two, bit of a bright amp stock. i played it for a while to get my ear in before starting on tone mods.
Ended up with a pretty good sounding amp actually.
Its pretty well blackface tone circuit, 2 gain stages into PI, no CF.
The drive channel takes the input stage, and diverts it to V2 and two gain stages. Basically 3 gain stage amp, and its got some cool tones stock, but bright.
I altered a few items and got its sounding pretty great really, its a good platform for some great mods.
Anyways, they have an inherent issue with blowing the pissy little 315ma HT fuse. Googling the problem shows everyone complains of this problem.
Having a look at the schem, it has a full wave rectifier and places the HT fuse on the grounded side of the rec rather than the positive side.
It has a 100uf first stage and then a 470R choke then 15uf screens.
The screens have a 100R(tho82R in this amp) resistor mounted between pin 1 and 9, ive lifted them up, off pin 1 as its an issue for some tubes.
Ive told the guy to use a 500ma fuse, but after sending it home it popped the fuse again. Im tempted to place it on the hot side of the rec, also was tempted to reduce the first cap to 50 uf for the sake of feel.
Anybody have any ideas related to the popping fuses?
Only schem i could find was herehttp://www.flickr.com/photos/digited/47 ... otostream/

[selloutrr]

have you metered the PT to make sure it's not acting up?
same with the diodes if they keep taking hits the fuse could be popping for a reason.
based on age of the amp? does it need filter caps?
If the parts all checks out the heater fuse is not a must have, you could bypass it. or try it post the rectifier.

[azatplayer]

No have not tried that. Yeah fuses everywhere on this thing. It has a toroid power trans too. Its not limited to this one amp, appears to be an inherent issue with this model.

[Mr. B]

Apologies for reviving a dead topic but have the same issue of fuses blowing on my Laney - did you ever come up with a satisfactory solution?

[Structo]

You know it's strange that on that schematic it says, they changed the HT fuse from 500mA to 315mA which doesn't make sense.

The mains fuse is shown as 1.5A which is low IMHO.

I have a 4x EL84 amp sitting here and it has a 3A Slo Blo on the mains.

I would try the 500ma Slo Blo on the HT for starters.

If your amp has a shorted power tube then that is a good reason for the HT to go.

[Masco]

When did the fuse blow, on power up or while playing?
Remove the fuse and measure the current across the fuse terminals on power-up. Try power, then standby and also try powering up with the standby in play position. See if there's a difference w/ in-rush current.