JLG Posted November 20, 2018 Share Posted November 20, 2018 (edited) Hi all I was in rehearsal for 5 hours y'day and all was well. Took my gear home - Hartke HA3500 through a 115 Hartke cab - and switched it on this morning but there was no power. I checked the fuses (in the compartment above the kettle lead) and of the 2 fuses, the T4AL 250v fuse has blown (the other fuse is T8AL and is fine). Any idea what might have caused it? Is this any indication of another issue? I have replacements on order (I couldn't find a store nearby that stocked them). Thanks in advance. Edited November 20, 2018 by JLG Quote Link to comment Share on other sites More sharing options...
BassBunny Posted November 20, 2018 Share Posted November 20, 2018 It could just be an age thing. I have had fuses blow on me for no apparent reason, (other than they had been there for ages). Put new fuse in and Robert's a relative. If the replacement blows, then you do have an issue. Do you know what each fuse does? Quote Link to comment Share on other sites More sharing options...
JLG Posted November 20, 2018 Author Share Posted November 20, 2018 47 minutes ago, BassBunny said: If the replacement blows, then you do have an issue. Do you know what each fuse does? I'm completely useless at the electronic side of stuff. Quote Link to comment Share on other sites More sharing options...
RichardH Posted November 20, 2018 Share Posted November 20, 2018 I think you will find that the second fuse is just a spare - it doesn't connect in circuit. Quote Link to comment Share on other sites More sharing options...
JLG Posted November 20, 2018 Author Share Posted November 20, 2018 (edited) 3 hours ago, RichardH said: I think you will find that the second fuse is just a spare - it doesn't connect in circuit. Really? So can I swap them over? If so, why are there 2 different fuses? Edited November 20, 2018 by JLG Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted November 20, 2018 Share Posted November 20, 2018 They're not different, or at least they shouldn't be. The back panel shows two values, one for 110v operation, one for 220v. Quote Link to comment Share on other sites More sharing options...
JLG Posted November 20, 2018 Author Share Posted November 20, 2018 (edited) 58 minutes ago, Bill Fitzmaurice said: They're not different, or at least they shouldn't be. The back panel shows two values, one for 110v operation, one for 220v. There are 2 fuses in mine: one T4AL 250v (which has blown) and one T8AL 250v The back panel says for 230v AC input it should be T4AL 250v, and for 15v AC input it should be T8AL 250v. I'm in the UK (just to clarify) on 230v AC so am I right in assuming it should be two T4AL 250v fuses? If not, what should it be? Again, thanks in advance. All this help and advice is very helpful. Edited November 20, 2018 by JLG Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted November 20, 2018 Share Posted November 20, 2018 If you're in the UK both fuses should be 4 ampere, if the purpose of the second fuse is to be a replacement spare. If the reason for having two fuses is to give the user the correct fuse for their supply voltage then they would be 4 amp and 8 amp. The truth of the matter should be revealed in the owner's manual. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted November 21, 2018 Share Posted November 21, 2018 We live in a frustrating world where things like fuses can pretty much only be found online. Hope you bought a lot of them. Even so I'd only try one more fuse, it that blows it isn't coincidence there's a fault and I guess that's not something you'd want to fix yourself. It's impossible to guess what's wrong from a distance but my experience is that there is a problem with the power supplies in the HA3500 with a lot of moderately sized capacitors slightly insecurely mounted on the circuit board. Over time these can pull away and even damage the board by pulling the tracks away. The good news is that unlike more modern amps the Hartke is easy to work on and the components are generally widely available and low cost so your bill shouldn't be too expensive. They are a lovely sounding amp though. Quote Link to comment Share on other sites More sharing options...
JLG Posted November 22, 2018 Author Share Posted November 22, 2018 All sorted now. Was the fuse. Whoever put 2 different fuses in was obviously mistaken. Thanks for the advice. It's very much appreciated. Quote Link to comment Share on other sites More sharing options...
Monatomic Rooster Posted December 9, 2018 Share Posted December 9, 2018 Two different fuses is the correct answer. If you study the schematic you will see that the mains wiring goes from the upper pin on the power connector (the live pin when using a UK plug) to the single pole switch then through the T8AL fuse, marked 115V, to the top of the upper transformer primary and the voltage selector. So the 8A fuse is always in circuit, regardless of the voltage setting. If the voltage selector is set to 115V, as in the schematic, then the T4AL fuse, marked 250V, is left hanging at one end and so is not in circuit. For 115V operation, therefore, the 8A fuse is relied upon for protection. If the voltage selector is set to 230V, as shown in dotted lines in the schematic, then the T4AL fuse is connected in series with transformer primaries and the TA8L fuse. Since the 4A fuse has a lower current rating than the 8A fuse, it will (at least in theory, and it usually does) be the only fuse to blow in the event of a current overload. So for 230V operation, only the 4A fuse is relied upon for protection and the 8A fuse merely says 'ouch, that hurt' when things go boom. This arrangement is just a sneaky way to simplify the wiring and reduce manufacturing costs. Hope it helps. Quote Link to comment Share on other sites More sharing options...
12stringbassist Posted December 10, 2018 Share Posted December 10, 2018 (edited) 1. Fuse sled - This contains a fuse holder and shows the currently selected voltage rating for your Model 3500/5500. Make sure the voltage rating is correctly set before powering up the amplifier! Fuse ratings are 10 amp for 115 vac and 6.2 amp for 230 vac. Has anyone got a link to the correct replacement fuses just in case? Edited December 10, 2018 by 12stringbassist Quote Link to comment Share on other sites More sharing options...
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