Mistakes you Learnt from! (might be helpful for beginners) - Page 3 - diyAudio
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Old 14th April 2013, 01:15 AM   #21
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Quote:
Originally Posted by HIPCHECK View Post

5. Get a Variac, Bulb Tester, Fuse board, and make a test rig.
Can you (or someone) give some guidance around what would be a good variac? Any particular specs or brand? Thanks.
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Old 14th April 2013, 03:48 AM   #22
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It is rumored that Steve at ApexJr still has several variacs on his shelf, but not listed on the website?
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Old 14th April 2013, 08:02 PM   #23
henryve is offline henryve  South Africa
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Get a set of Spotting Drills for drilling holes position perfect. When countersinking into Aluminium, use a Hole-type Countersink bit. I have tried all the tricks with the Fluted types but they still chatter.
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Old 14th April 2013, 08:50 PM   #24
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Don't try to catch a hot soldering iron that's falling off the bench...
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Old 15th April 2013, 12:35 AM   #25
Telstar is offline Telstar  Italy
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Originally Posted by sakellogg View Post
setup 2 meters when you are testing for voltage and current. use one for volts and one for current.
ive killed parts before, forgeting to swap back using 1 meter.
How did this happen? I can switch easily from DCV to A on my Keithley...
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Old 15th April 2013, 12:37 AM   #26
Telstar is offline Telstar  Italy
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Originally Posted by AndrewT View Post
Multi-meter probes with exposed metal.

Insulate the probe tips so that only the last 1mm is exposed to accidentally touching other components.
Great advice. I have to do this for where the miniclips cant enter
I'd add to solder resistors with more space over the pcb so the miniclips would fit and stay anchored
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Old 15th April 2013, 12:39 AM   #27
Telstar is offline Telstar  Italy
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Quote:
Originally Posted by Danger Mouse View Post
double or triple check correct position of your parts at PCB
For me, double check parts orientation BEFORE soldering them
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Old 15th April 2013, 03:54 AM   #28
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1. Build your power supply first. Test it, using a bulb tester and confirm your "no load" voltages.

2. Build one amp channel next. Ground the inputs for your first tests. Do NOT test with an expensive loudspeaker system. Connect it to the power supply and test. Use the bulb tester at first. (Read, don't blow out TWO channels of an amp, just because they both have the same wiring error!)

3. Build the second channel. Wire it the same as the first. Connect and test.

4. Don't tell you're "significant other" how much you are spending on transformers, heatsinks and your F5X projects......!!
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Old 15th April 2013, 08:12 PM   #29
AntonTR is offline AntonTR  Russian Federation
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Measure twice, cut once... And... Hundred times of regrets!
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Old 15th April 2013, 08:37 PM   #30
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Quote:
Originally Posted by Telstar View Post
How did this happen? I can switch easily from DCV to A on my Keithley...
On the Flukes (handhelds) that I'm used to using, to measure current you not only have to switch to the 'current' setting on the selector switch, but you must also swap the positive lead from the 'V-ohms-diode check' input to the 'A' input. In this configuration, the meter is basically a dead short lead to lead, and (in my case anyway) fused at 10A.

If, without paying enough attention, you measure current and then later switch to voltage and go to take a measurement without swapping the lead back to the V jack, you wind up putting a short that can carry 10A across whatever you're trying to measure the voltage of. Something then frequently goes 'poof'. It may be the fuse in the meter, or it may be something in the circuit you're measuring that doesn't like short circuits. I could say I've never done that, but it would be a lie.

I'm guessing that your Keithley doesn't require the input to be swapped for current measurements. Is it a bench meter, rather than a handheld?

-Pat

Last edited by Cubdriver; 15th April 2013 at 08:39 PM. Reason: spelling
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