DawnPatrol1990 Posted April 10, 2016 Share Posted April 10, 2016 Hey I've got a Hartke HA3500 and it seems to have a small problem... 10 minutes after turning it on, it completely turns off and doesn't come back on for ages, about 30/45 minutes ish. I felt the casing and the amp was extremely hot so it's obviously overheating. After removing the top of the case, it seems to be the big coil looking thing (excuse my technical terms) at the back of the amp that is overheating. The fan is spinning so it's not like that's not working or whatever either. I'm only running the cab in to a Ampeg SVT410HE 200w cab as well and not running any effects. Has anyone had this problem and is it any easy fix? Thanks in advance! Quote Link to comment Share on other sites More sharing options...
mikeydee Posted April 10, 2016 Share Posted April 10, 2016 Hi, The cutting out is a good sign. It means the amp's protect circuit is working. The hot thing - if it is the biggest square thing in there just behind the centre fan then that is the power transformer . It should get warm but it will get very hot when there is a fault somewhere as it is delivering all the electricity to the different parts of the circuit including the part with a fault. It might be bad itself but hopefully the fault is elsewhere. Few questions: [indent=1]What's the amp's history - is this a recent purchase or have you had it for a while.[/indent] [indent=1]During the ten minutes when it is on, are you playing or is it just idle. If you did play, would it work. Also, if possible connect the line out or FX send to another amplifier's input and see if signal is coming out of the Hartke and whether it sounds ok - this would give an indicator that the pre-amp is good.[/indent] Ideas: There are two fans on this amp and both should be spinning. The rear centre one blows air in and the little one on the power amp module (left hand side) blows warm air out. Maybe the little fan on the power amp module isn't working? Fault Possibilities are:[list] [*]power amp module (left hand side) [*]Pre Amp inc valve (front) [*]Power Supply (transformer, big capacitor cans and associated parts) [/list] Either way it will need to go to a tech and probably a bit of a repair bill I am afraid. Depending on where you are located I may be able to help you find a tech. Sorry not better news. Quote Link to comment Share on other sites More sharing options...
DawnPatrol1990 Posted April 11, 2016 Author Share Posted April 11, 2016 Ah damn this doesn't sound good =/ From what you've said, it is the power transformer. The big round thing that looks like a big ball of coils with all the wires coming off it. In all honesty, i haven't owned it very long but when I bought it, the guy I got it from said "it's never let him down" and "it's been a real work horse" so i took his word for it. When i have it plugged in, i've been playing my bass through it but I usually run the EQ totally flat with a tiny (and i mean tiny) boost in the high end. I have the pre amps on the 3500 set so the Tube pre is at 12 o clock and the Solid State is as 9 o clock just to blend some of it in so in no means am i pushing the amp. I'll see if i have any other small amps laying around that i can connect the line out and effects out to one of them to test it all. As it's currently 2am, i obviously can't do that until the morning but i'll give it a go once i wake up. In the 10 minutes it actually stays on for, the amp sounds great. The rear fan spins but blows out extremely hot air. I will check for the smaller fan on the inside that you're saying about though. Typically, i brought the amp from a guy in Bristol but live no where near there. The good news is that Hartke/Korg UK is only about 20 minutes away from where i live so I might drop it in to them some time soon. Thanks for your help so far though, any other advise would be appreciated! Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted April 11, 2016 Share Posted April 11, 2016 (edited) [quote name='DawnPatrol1990' timestamp='1460336726' post='3024787'] ...any other advise would be appreciated! [/quote] We have an HA3500; had it from new. Very shortly after the end of the guarantee, it stopped working; the toroidal transformer (yes, that big fat coily thingy...) had gone duff. After much research, I finally tracked down that Korg address, and they sent me (here, to France...) the right trannie, and the problem was rapidly fixed. It's worked fine ever since (a few years ago, now...). The bad news, then, is that these trannies [i]can [/i]go duff. It's pretty rare, and not necessarily through abuse (ours was never 'thrashed', nor even half-used...). The good news is that, in the right hands, it's a quick and (relatively...) inexpensive job, and those Korg folks [i]are [/i]'the right hands'. An unexpected expense, which is always a sod, but once repaired, it'll probably give many years of loyal service. Don't mess about; just take it to 'em and they'll sort it out. Hope this helps. Edited April 11, 2016 by Dad3353 Quote Link to comment Share on other sites More sharing options...
mikeydee Posted April 11, 2016 Share Posted April 11, 2016 Ah ok sounds there are different transformer depending on year. Mine is a square one that construction is known as an EI transformer. Yours is torroidal or doughnut style. Usually a transformer fails it is with a short on the winding. I doubt that is the problem in your case as it sounds like it working for a while and then shutting down due to thermal protection. Not sure if korg do repairs but they are excellent with parts like the little LED pots etc. A transformer is expensive stuff est £80-100 so best to get someone qualified to verify the fault before spending. Quote Link to comment Share on other sites More sharing options...
SubsonicSimpleton Posted April 11, 2016 Share Posted April 11, 2016 (edited) edit:didn't read thread properly, nothing to see here Edited April 11, 2016 by SubsonicSimpleton Quote Link to comment Share on other sites More sharing options...
DawnPatrol1990 Posted April 18, 2016 Author Share Posted April 18, 2016 Thanks to everyone for their advise and comments so far. It's actually been a lot of help. I've had the amp looked at by Hartke in MK and they say the transformer has completely burned out which is a great problem to have. I managed to find a replacement 3500 transformer on the net for £80 so i've bought that and am going to take it to be fitted by a local tech. Hartke wanted £40 inspection fee (which would raise to £51.50 if i declined the work they needed to do) followed by £60 an hour labour and then parts cost on top. For what it would end up costing for them to fix it, I could have bought another one so I've taken the easy route. If this fails then i'll sell the amp on for spares and look for a new amp. I'm just glad the amp's heating protection circuit has been working and not caused more damage. The pre-amp etc all sounds damn great so i really hope it works after this. Any other help would still be appreciated. Quote Link to comment Share on other sites More sharing options...
mikeydee Posted April 18, 2016 Share Posted April 18, 2016 Did hartke quote for the new tranny? Just curious like Quote Link to comment Share on other sites More sharing options...
DawnPatrol1990 Posted April 19, 2016 Author Share Posted April 19, 2016 No they didn't and with the rough prices i've seen them selling at on the net (just random transformers), I'd hate to think what they'll try and charge Quote Link to comment Share on other sites More sharing options...
mikeydee Posted April 20, 2016 Share Posted April 20, 2016 Sounds like a good plan. I would expect it to be up to £120 shipped so your second hand one seems reasonable. Good luck with the fix. Quote Link to comment Share on other sites More sharing options...
DawnPatrol1990 Posted April 21, 2016 Author Share Posted April 21, 2016 New transformer arrived this morning. Good news? It's brand new and un-used. Bad news? Ha... you'll love this... Wrong size (far too big for the amp), wrong connector wires on 2 of the 3 wiring looms and wrong voltage. I've applied to the company to send it back. Awaiting a refund now hopefully. In the mean time, the amp is back in the garage and i'm sitting in a corner, rocking back & forth whilst crying incoherently haha. I JUST WANT MY AMP TO WORK Think it's time to give in with it and go for a new amp maybe? Quote Link to comment Share on other sites More sharing options...
BassHertz Posted July 22, 2016 Share Posted July 22, 2016 Had one of these with a similar overheating fault. turned out to be the bridge rectifier and the two large capacitors on the power supply. IMO Hartke should have added two fuses on the two supply rails from the transformer feeding the amplifier section, as there is not enough protection for the transformer. I totally relies on the overheat protection and a single fuse on the mains input side - I added them myself Quote Link to comment Share on other sites More sharing options...
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