Ashdown Mag 300 Crackling Input

T

Tony Burton

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May 8, 2018
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#1
I acquired an Ashdown MAG 300 Amp from a mate who emigrated and wanted to test it before selling it for him.
I don't have any instruments to test it with as he took his guitars with him, but with an audio cable from my Pc I can get it working ok. The only problem is it crackles when the Input dial is turned. Is this normal?
 
#2
Crackle shouldnt be normal.

If its been sitting awhile or previous owner left volume at same setting all the time. Could just be dirty volume potentiometer or hot spots. Just need to clean the pot.

Otherwise if its soundcard crackle the level being sent to the computer is too high or. Using low latency settings is pushing the processor.
 
#4
Don't use anything but a tiny bit of Caig DeOxit to clean the pot. (Yes, I see plenty of pots that are ruined by using other compounds, and from using too much of anything.)
 
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#7
WD40 isn't contact cleaner, and you don't want contact cleaner anyway.

Yes DeOxit is expensive, it's also the right tool for the job. 1 can lasts me several years and I myself work on over a hundred amps a year.

Other compounds can damage the carbon track, attract dirt, become gummy (especially WD-40), and cause lubricants to migrate to places they should not be from places where they are essential.
 
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#8
THanks I appreciate the advice guys, but I didn't mean WD40 the substance, I meant the Brand - i.e. this:
https://www.amazon.co.uk/WD40-Dryin...id=1525876368&sr=8-1&keywords=contact+cleaner

When I research Caig Deoxit, there are two types, regular and gold - which should I use?

Also, I had anticipated simply spraying a fast drying chemical into the pot and then rotating the knob until it had evaporated. How should I use Deoxit? The pot is shown in the photo attached. Hypodermic needle - a few drops into the hole and then rotate knob?? I could probably get an interdental brush in there and swish around a bit??

Cheers
 

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#9
You're in the UK? There is a DeoxIt equivalent available in Europe, or so I've read here. I don't know the name. That might cost less. I've only used DeOxit 5, the other I think is more concentrated. If you have a spray, wrap the part in a paper towel so it doesn't spray out and onto the board and other parts, then just give it a very small, short burst of spray into the opening on the side. You about can't get too little. If you end up with a bottle of liquid, just a drop applied with a toothpick should be plenty, or a drop from a syrigne.

For the other brand, I'll bet @ThisBass will know what to use.
 
#10
Tony Burton said:
THanks I appreciate the advice guys, but I didn't mean WD40 the substance, I meant the Brand - i.e. this:
https://www.amazon.co.uk/WD40-Dryin...id=1525876368&sr=8-1&keywords=contact+cleaner

When I research Caig Deoxit, there are two types, regular and gold - which should I use?

Also, I had anticipated simply spraying a fast drying chemical into the pot and then rotating the knob until it had evaporated. How should I use Deoxit? The pot is shown in the photo attached. Hypodermic needle - a few drops into the hole and then rotate knob?? I could probably get an interdental brush in there and swish around a bit??

Cheers
Click to expand...
Get the Deoxit D5 only. Here is a small can.
https://www.amazon.co.uk/Deoxit-DN5...UTF8&qid=1525883872&sr=8-6&keywords=deoxit+d5

The can has a setting on the nozzle for Low, Medium and High, set it to low.
Use the straw and just a spit in the hole, then move the knob around a few times and that is all.
LESS IS MORE, ANYTHING MORE WILL DESTROY IT.

This is the best picture I could find. Turn the head to the L setting.

349-215_ALT_1.jpg

Yes, it is expensive but it is the right tool for this job. Use some on the battery terminals on your car once or twice a year and they will look as new. My 96 Volvo terminals look factory fresh while other peoples I work on have white fuzz after only a few years.
 
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#11
Tony Burton said:
THanks I appreciate the advice guys, but I didn't mean WD40 the substance, I meant the Brand - i.e. this:
https://www.amazon.co.uk/WD40-Dryin...id=1525876368&sr=8-1&keywords=contact+cleaner
Click to expand...
No, this will strip the essential lubricants from where they are needed and mess with the other lubricants by putting them where they shouldn't be.

Tony Burton said:
When I research Caig Deoxit, there are two types, regular and gold - which should I use?
Click to expand...

Regular D-5. I prefer the 5% spray, using only the tiniest amount. This leaves the ideal amount of track lube witjout any chance of damage.

Tony Burton said:
Also, I had anticipated simply spraying a fast drying chemical into the pot and then rotating the knob until it had evaporated. How should I use Deoxit? The pot is shown in the photo attached. Hypodermic needle - a few drops into the hole and then rotate knob?? I could probably get an interdental brush in there and swish around a bit??

Cheers
Click to expand...

The 5% spray is what I prefer, tiny amount. I don't care for the 100% needle application (except in some very specific applications) because it leaves too much residue.

NEVER put anything inside the pot, there are some very fine cantilever spring contact fingers that are easily damaged. Once even the slightest damage occurs, the pot is ruined for good. Just a tiny spray and rotate a few times. Less is more.
 
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#14
When cleaning jack shunt contacts or any metal-to-metal contacts with Deoxit, use a small brush to scrub the oxidiztion away.

Inter-dental brushes work well. The bristles are soft, non-abrasive, and unlike with simply spraying, helps with the cleaning action of the Deoxit.
 
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