HRD Randomly switching channels

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Hi I've just bought an HRD from gumtree. (fatal error!)
Plugged it in at home, sounded great.
10 minutes or so later, the thing randomly starts flickering from the clean channel to the drive.
I'm pretty p'd off to be honest!

Any ideas if it's an easy fix or shall I just return it?
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Comments

  • Seems to go away if I plug the footswitch in
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  • hywelghywelg Frets: 4302
    I had that happen with my HRDx about 12 years ago. Fault in the switching system. Probably need to take it to a tech. 
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  • Danny1969Danny1969 Frets: 10357
    There is two big resistors which drop the volts  down  to run the opamps and the switching  circuit .. the joints on the board tend to go bad there  due to the heat. Not a difficult thing to fix in general 
    www.2020studios.co.uk 
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  • ICBMICBM Frets: 71960
    If it stops when you plug the footswitch in, I think it’s the switch contact in the footswitch jack. Cleaning it with some Servisol should fix it.

    The resistor problem Danny mentions will do that too, but it won’t stop when you use the footswitch, and the reverb and FX loop will stop working as well, so you can check for this by plugging a short patch cable in the loop (to turn it on) - if the sound now erratically cuts out, most likely it’s the resistors. It’s not a difficult repair for someone familiar with working on them.

    If you are taking it to a tech, get them to wire it for 240V not 230, it makes them less hard on these resistors - and the valves.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • DJH83004DJH83004 Frets: 196
    Not a fatal error buying from Gumtree, if you got it at a good price with a bit of float to put thinks right, the +/- LV dropper resistor joints  plus the zeners are an easy fix to any tech who has ever worked on a HRD, and if it is the footswitch jack as per IC, even easier. 





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  • MattFGBIMattFGBI Frets: 1602
    Do you know how old it is?
    This is not an official response. 

    contactemea@fender.com 


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  • Thank so much everyone for your help. 
    @MattFGBI I’m not sure what year (can check later when I get home) but I think it’s an old one, I’d put links up to gumtree/eBay to the ad I got it from but don’t want to publicly involve the guy as he may not have realised it had this problem.
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  • I might add that it seemed to worsen with higher volumes and more bass, which to me further points to the possibility of it being a problem with the footswitch jack, possible a short that gets vibrated in and out of contact..? ( sorry, I don’t really know what I’m talking about!)
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  • ICBMICBM Frets: 71960
    It’s not a short - it will be an intermittent open circuit, either the switch in the jack (which disables the footswitch and allows the panel switches to work when no plug is in the jack) or a cracked solder joint on one of the pins for it.

    A tiny bit of corrosion in the contact - if the footswitch has rarely/never been used - or a cracked joint if the cable has been tugged hard, can do one of these things.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Ok cool. I’m going to have a proper look at the jack and see if there’s any obvious damage, I’ll spray some servisol in there too. 

    Thank you 
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  • ICBMICBM Frets: 71960
    edited February 2018
    Try the Servisol first, definitely - you don’t even need to open the amp up for that, just spray some into the jack.

    If it’s the second version of the amp with the better-quality footswitch and input jacks (chunkier metal nut than the Preamp Out and Power Amp In jacks) then the contact can be physically cleaned with the back off the amp if necessary. If it’s the first version with all-identical jacks, or a cracked solder joint, then the board has to come out unfortunately.

    If you’re going to open it up yourself, you can check/swap the mains voltage setting as well, that’s just two push-connectors on the board.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • timmysofttimmysoft Frets: 1962
    It just wants to be on drive.

    clean is for pensioners, students and Russian spies 
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  • I’ve sprayed servisol into the jack and that seems to have done the trick
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