250 ml and 500 ml amp fuses for ht20 combo

Discussion - HT Venue amplifiers. Inspiration from Studio to Stage.
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Posts: 56
Joined: Thu Apr 07, 2011 12:00 am

Tue Oct 25, 2011 1:54 am

Okay.. Fuse fixed the problem.. Even though the htfuse looked fine it was not.. Autozone (good ole autozone) ran a fuse tester on it and it was no good.. Looked all over creation and back auto store, wallmart, music store blah blah blah.. No 250 ml fuses.. Radio shack on the other side of town not the dumb ones that told me they had never seen this fuse before came up with a 500 ml 250 volt slo blow fuse that stated it will work.. The nerd at radio shack told me they are probably ok for a backup but would not run them and get the orig fuse.. I contacted my local store that I bought the amp from they called Blackstar as they are a dealer.. Blackstar told em we don't sell the fuse because they are available locally.. Now I feel like kickin blackstar rep right in the ass because if they are available locally I wish they would tell me where.. My music store at home is going to call them and ask the same thing...Until then I know the amp works and it is nothing but a fuse issue because I put the 500 in complted the circuit and rocked the f out for about 20 mins with no issue..

My question is.. The 500 is rated for less amperage than the 250.. The 500 is only a 1/2 amp fuse and radio shed told me the 250 is a 1/4 amp fuse and can handle more.. Logic I will never get my pea brain around because math class always tought me half was more than a quarter..Whatever..

Am I going to fry the f out of the amp running her with the 500 in it.. I really at this point dont care to shut it down until I get the proper fuse because I now know at least it does not have to go back to england or wherever the f it is they send these things for a tube swap (something that from what I have read should be user serviceable) --again thanks blackstar wtf?..

I emailed blackstar about tube swap and they told me not to do it or it would void the warranty and make me not cool anymore.. wtf...

anyone? anyone know about fuses and mili amps and all that crap? Again thanks for all who posted to my previous posts at least we the people are helping each other...

Posts: 206
Joined: Thu Sep 15, 2011 12:00 am

Tue Oct 25, 2011 3:07 am

Using the wrong fuse won't hurt the amp if its in good working order.

But if there is a problem, then the fuse could fail to trigger and something else may break. I'm no expert. Using a slightly higher rated fuse (okay, double rating) is better than some people who stick 10x rating fuses in their amps (or a penny) and then end up in big, big trouble when the whole thing melts down.

Ideally, you would go easy on the amp until you get the right fuse, and see if it blows. if it blows repeatedly, then you may have a problem that needs addressing. But yea, the original could have just been bad.

Shame on Blackstar for not spending 50 cents or whatever it would cost to include a spare fuse with the amp like other makers do.

The warranty issue on the tubes is silly, it's not as if they can tell if you changed them or didn't, esp. since the HT-20 doesn't need to be biased. But yea, if it's new, I wouldn't mess with it.

This is food for thought on what to do if it keeps blowing fuses http://www.eurotubes.com/euro-i.htm#14.0

Yours is new, and the tubes should still be good (for at least 6 months of heavy gigging, or maybe 3+ years of lighter playing). So I'd say get a new fuse, hope it works, and if problems persist, use the warranty.

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Posts: 191
Joined: Tue Nov 23, 2010 1:00 am
Location: Wellesley, Ontario, Canada

Tue Oct 25, 2011 3:19 am

For the record, the HT fuse in my HT-20 was changed a year ago and it hasn't blown again. I even ran all the stock tubes for 8 months. Maybe a faulty fuse?

Here's the thread in which we talked about my problem....

Posts: 56
Joined: Thu Apr 07, 2011 12:00 am

Tue Oct 25, 2011 5:11 am

Thanks fellas.. APpreciate the feedback.. I will probably just leave it unplugged and quiet until I get another fuse.. probably the best.. With my luck if I played it with the 500ml fuse in it the devil would spring out of the front of it and take my soul to tube amp hell where I would find a Blackstar rep that would tell me these fuses are available anywhere and I cannot change my tubes myself because it would curse me and my wife and kids to transistor amp doom..

I really wish they would just tell us if we could swap the power tubes.. I would like to try some different tubes to see what tones I cold coax out of this amp.. THe stock tubes sound marvelous to me but then again I am coming straight off of owning an 80 watt line 6 digital amp.. I thought it sounded all good on the killswitch engage setting when I was rocking with the bros but after owning the tube amp and hearing its wonderful distortion I cannot go back..Not to mention the slightly overdriven cleans when we play petty and classic stuff..

When you turn up the treb a little and the bass a little and leave the mids low the chunk and the bite is f'n awesome.. I am hooked like a crack head. Palm muting and heavy pick attach during rythm sections has me f'n hooked on this thing.. We play Back and forth by the foo fighters and it sounds like the gaddam cd is playing when we rock it.. all due to this amp.. I run the htboost , small clone, orig baby wah (dunlop) in the chain and it smokes out awesome tones.. Handles all my solos and leads better than any amp I have owned too.. I play rythm/lead and sing..

No pedal usage with a digital amp and that is another reason I got rid of that tinny soundin shit..I guess digital amps are more reliable but all my guitars sounded the same.. F that.. I need character because all guitar should not sound the f'n same..

It likes both my fender mexi strat (yeah I bought a cheapo but it played better than all the americans at the store) and my go to bitch my Les Paul vintage burst studio 60's deluxe.. The Gibson f'n wales through this thing.. Now I jus got to find the right f'n fuse so I guess I just keep hunting or order them online..

Oh wait per Blackstar I can just go anywhere around town and get one.. My ass Blackstar.. FTW!

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Joined: Mon Sep 16, 2019 12:34 pm

Tue Sep 17, 2019 9:11 am

Crunchifyable is right, putting a fuse in with a higher current rating will not harm the amplifier unless it develops a fault like a shorted output tube. In that case you could fuse the primary winding on the output transformer - expensive!

500mA = 0.5A fuse takes twice the current before blowing of a 250mA = 0.25A fuse, your maths teacher was right.

I have an HT Studio 20 here that keeps blowing it's HT fuse of T250mA (T means slow blow from the German word 'Träge' which translates as 'sluggish'). I cannot find any faults on it. It is possible that the owner has been turning it off and on again before letting the tube cathodes cool down which can apply a high voltage across the OP tubes while they are turned on. You don't want to get zapped by a high voltage while you are turned on, it can be painful, phnar phnar! There is no standby switch on an HT20 so the HT is always applied. Removing the input jack does turn the output tubes off at the gate to lower power use.

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