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Vintage threads from the first ten years
Re: HELP! - Fender Tonemaster knackered (?)......
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 5/23/2000 1:38 PM |
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Stephen Conner |
Re: HELP! - Fender Tonemaster knackered (?)...... Ray,
I'd be surprised if the rectifier in a DMM could cope with ultrasonic signals. Have you had any success with this before? Steve C. | |
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| 5/23/2000 4:40 PM |
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| Ray Ivers |
Steve, I was going to mention the possible lack of meter sensitivity to ultrasonic signals in my post, but I figured that a) most guitar amp oscillations I've seen are pretty low in frequency (below 50 kHz) and b) if the thing is glowing the tubes with power output, I imagine an auto-ranging DMM will pick it up no matter what frequency it is, unless it's way up above 1 MHz or something. I don't really know what the average cutoff frequency is for DMM's - it's a spec I never think to check, but I should... I always use a 'scope when troubleshooting, so I can't really say I have first-hand knowledge that this meter method will work, but the next time I get a 'squealer' I'll be sure to check it out (come to think of it, my signal generator goes up to 100 kHz - I could do it right now). Thanks for the notice! Ray |
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| 5/23/2000 5:53 PM |
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| Ian Anderson |
Bob! I've rung Arbiter (UK) and they said they'd be charging £45 per hour to look at it which is just insane - I can't afford that sort of money *per hour* at present, or ever for that matter. Unless your mate knows everybody and can get it done for a *reasonable* price (i.e. not £45 per hour), it might not be worth it - cheers for the offer anyway. I have checked all of the obvious things like speaker cab, leads, fuses, guitars etc... and for obvious reasons didn't have any stomp boxes in-line when trying to figure out the problem. I'll probably end up taking it to one of the techs I've contacted in other parts of the country who seem knowledgable and are ex-amp-company engineers. Lastly, what's the cardboard box/blanket trick? ... Ian |
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| 5/23/2000 8:32 PM |
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| Bob |
My mate, if can get him on phone, will probably suggest someone outside of Arbiter, probably near where you are. He's been in the biz a long time and knows alot of folks. Alot of techs use a carboard box to put over an amplifier when they suspect a problem that only appears once the amp has heated up alot. It saves the tech's time as he can simulate certain conditions without having to wait an hour or two. It's a common technique with thermal problems. Bob |
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| 5/26/2000 1:21 AM |
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| Rick Erickson |
I've done that but I usually use a hair dryer to expediate the heating process. It's the only use it gets anymore... RE | |
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