Crackling Amp- tech required

[gemdids]

Fellow BC'ers,

Can anyone reccommend an amp tech in Manchester who could take a look at my amp- Hartke A100. The volume switch crackles quite badly, it's ok once it's set but it's taking me a while to find a sweet spot where it's stable, apart from that it cuts out or distorts. If anyone nearby thinks they could have a go at fixing it, be my guest!

Gemdids

[flyfisher]

[quote name='gemdids' post='1356016' date='Aug 30 2011, 10:19 AM']Fellow BC'ers,

Can anyone reccommend an amp tech in Manchester who could take a look at my amp- Hartke A100. The volume switch crackles quite badly, it's ok once it's set but it's taking me a while to find a sweet spot where it's stable, apart from that it cuts out or distorts. If anyone nearby thinks they could have a go at fixing it, be my guest!

Gemdids[/quote]
You could try cleaning the volume "switch" yourself (I presume you actually mean a volume potentiometer) with something like this: [url="http://www.maplin.co.uk/switch-cleaner-27515"]http://www.maplin.co.uk/switch-cleaner-27515[/url]

[gemdids]

[quote name='flyfisher' post='1356025' date='Aug 30 2011, 10:30 AM']You could try cleaning the volume "switch" yourself (I presume you actually mean a volume potentiometer) with something like this: [url="http://www.maplin.co.uk/switch-cleaner-27515"]http://www.maplin.co.uk/switch-cleaner-27515[/url][/quote]


I haven't tried that, to be honest, with electrics and technical things the like, I prefer to leave it to the experts. By switch, yes, the potentiometer (see, I didn't even know thats what it was called!)

[Mr. Foxen]

Other thing it could be is a failing capacitor leaking DC into the pot, which you can check with a meter, bit more involved, and involves poking about in a live amp with probes.

[url="http://basschat.co.uk/index.php?showtopic=198"]So see this thread.[/url]

Edited August 30, 2011 by Mr. Foxen

[paul_5]

Chances are it's a cracky pot. Some witch-cleaner from Maplins (or similar) should sort it out. Failing that a replacement part is less than a fiver. anything else I'd take it to a recommended amp tech - there's a couple of local ones on pinned somewhere on this site (can't remember exactly where though).
HTH

[brensabre79]

Try Dave Lunt in Stockport.
Haven't seen him in a while, but he is v.good

0161 432 9698

[icastle]

[quote name='paul_5' post='1356145' date='Aug 30 2011, 12:00 PM']Some witch-cleaner from Maplins (or similar) should sort it out.[/quote]

[icastle]

It's dead easy.

1) Make sure the amp is unplugged from the mains.
2) Take the top cover off and locate the volume control.
3) The volume control has a gap on the bottom where the contacts come out and join the circuit board.
4) Using the straw that comes with your can of switch cleaner, give the control a good squirt into that gap.
5) Turn the control backwards and forwards quickly for 10 seconds - that'll dislodge any crud that has got in there.
6) Repeat the above to give it a final wash out.
7) Put the top cover back on and hopefully you'll be crackle free.

If that doesn't work then the chances are that the pot needs replacing - not a difficult job in itself but takes a little while to do as a lot of the chassis needs to be dismantled to get to the underside of the board and requires some soldering skills.

Spare parts are easily available from Korg (UK) who are the current Hartke importers.

[flyfisher]

[quote name='gemdids' post='1356031' date='Aug 30 2011, 10:35 AM']I haven't tried that, to be honest, with electrics and technical things the like, I prefer to leave it to the experts. By switch, yes, the potentiometer (see, I didn't even know thats what it was called!) [/quote]

No problem. I'd only encourage people to try the simple stuff if they're not happy about soldering and the like. icastle has described the process and hopefully it's clear that it's not really 'electrical' or 'technical', more of a cleaning process really. The only tricky bit is gaining access to the pots, but that should only involve a few screws.

At least you now know the first thing that an 'expert' will probably try.

Incidentally, if you ever have a similar problem with the slider pots, they can be cleaned by the same method without having to unscrew anything.

[Deep Thought]

I thought you were looking for an amp tech who crackles!

[icastle]

[quote name='Deep Thought' post='1356348' date='Aug 30 2011, 02:56 PM']I thought you were looking for an amp tech who crackles! [/quote]

As opposed to the witch in the bath who cackles...

[icastle]

[quote name='flyfisher' post='1356315' date='Aug 30 2011, 02:26 PM']The only tricky bit is gaining access to the pots, but that should only involve a few screws.[/quote]

Yes.
Once the top cover is off it's just a matter of tilting the amp until you can get a squirt of switch cleaner in there - accuracy isn't too important as long as some of it gets in there (a bit of kitchen roll screwed up and wedged into place to soak up the effects of gravity on fluid never goes amiss).

The real pain is having to change the pot on the Hartke's - I've done a few of these and access to the underside of the circuit board was designed by a man with a screw fetish...

[Mr. Foxen]

The pain is when you squirt it into the pot, and it squirts out another hole into your eye.

[gemdids]

[quote name='icastle' post='1356293' date='Aug 30 2011, 02:03 PM']It's dead easy.

1) Make sure the amp is unplugged from the mains.
2) Take the top cover off and locate the volume control.
3) The volume control has a gap on the bottom where the contacts come out and join the circuit board.
4) Using the straw that comes with your can of switch cleaner, give the control a good squirt into that gap.
5) Turn the control backwards and forwards quickly for 10 seconds - that'll dislodge any crud that has got in there.
6) Repeat the above to give it a final wash out.
7) Put the top cover back on and hopefully you'll be crackle free.

If that doesn't work then the chances are that the pot needs replacing - not a difficult job in itself but takes a little while to do as a lot of the chassis needs to be dismantled to get to the underside of the board and requires some soldering skills.

Spare parts are easily available from Korg (UK) who are the current Hartke importers.[/quote]


Thank you! I will try this as my first port of call. I've already unscrewed the amp from the speaker and had a look to se if there was anything obvious that had come apart or was sticking out. I will get some of that 'witch cleaner' this week and give that a go. Failing that, I'll leave it to the experts.

[gemdids]

[quote name='brensabre79' post='1356235' date='Aug 30 2011, 01:18 PM']Try Dave Lunt in Stockport.
Haven't seen him in a while, but he is v.good

0161 432 9698[/quote]

He will be my second port of call if the switch cleaner doesnt work. I'm off now to buy some.

[gemdids]

It worked! A couple of squirts of switch cleaner and it's as good as new, thanks folks

[icastle]

[quote name='gemdids' post='1357627' date='Aug 31 2011, 03:20 PM']It worked! A couple of squirts of switch cleaner and it's as good as new, thanks folks [/quote]

Excellent!!!

Next weeks tutorial will be 'How to perform an emergency appendectomy' so stay tuned...

[gemdids]

[quote name='icastle' post='1357637' date='Aug 31 2011, 03:28 PM']Excellent!!!

Next weeks tutorial will be 'How to perform an emergency appendectomy' so stay tuned... [/quote]

Can I put a request in for a tutorial on how to perform an emergency landing? Much sexier

[icastle]

[quote name='gemdids' post='1358787' date='Sep 1 2011, 01:50 PM']Can I put a request in for a tutorial on how to perform an emergency landing? Much sexier [/quote]

Well if from any great height there are two things to remember:

1) Cross your legs on the way down.
2) Hold one arm up.

You'll still die but at least by holding your hand up, the emergency services will know where to find you and the crossed legs makes it easy for them to unscrew you from the ground...