Basic Workbench Safety
At Various Levels
I am not speaking to tooling – except in passing, with the reasoning. And I am not speaking to functions except as they affect safety. There will be a separate paragraph at the end that will touch on some tooling and reasoning for the same.
Most Basic Level: This would be for users that do the occasional kit assembly, occasional cleaning, but no substantive testing of equipment and no specific voltage checks or exposures to open circuitry. This individual *might* own a VOM, but generally would not use it for this work, except to do bias checks. Items on this bench would not be plugged in, except as fully-assembled devices in the final stages of testing and initial operation.
Safety:
• Clean, dry non-metallic work surface of sufficient area for good access and a clear view, and for all tools, parts and pieces to be used and/or placed without clutter.
• A non-conductive, comfortable chair with pivoting functions and, preferably arms.
• Lighting: Excellent lighting not only aids assembly, but is a significant safety feature in its own right. I suggest at least two articulated (architectural-type) lamps, one with a magnifier, if possible. This permits shadowless light as well.
• High-quality tools. All hand-tools such as screw-drivers, files, pliers, cutters, needle-nose, and so forth should be exclusively of US or Euro origin, without exception or discussion. If ever one has cut a high-tension wire with a Chinese tool and seen it vaporize and spread hot metal over a cubic foot of area, one will understand this instantly – and the hard way.
• Soldering Device: Something with variable power, but a minimum of 35 watts if fixed. Preferably with replaceable tips. And with a flat-blade IRON tip. It is better to use a hot iron for a short time than a cool one for a longer time.
• Eutectic Solder: 37/63 if lead/tin. 3-part Cu/SN/AG (very expensive) if RoHS compliant. ACCEPT NO SUBSTITUTES.
• Excellent ventilation: Solder flux, other smells and such are not good. Repeat – EXCELLENT ventilation.
Next Level: May do some actual testing. May do some troubleshooting, but consisting mostly of testing voltages and cleaning pots and jacks. But items may be PLUGGED IN and operating with exposed high-voltage parts. So, to the above add:
• ISOLATION TRANSFORMER: something capable of handling any anticipated load or piece of equipment you might need to test. This varies by the need, but should start at a minimum of 3A (Continuous) rating, to as many as one can afford. The purpose of this is to isolate you – the operator – from the local ground plane such that if you do touch a 525 V B+ node, you do not die.
• High end VOM: You will pay and pay and pay for a cheap device. Start with Fluke – and work down until you can afford it. But, really, try to stick with Fluke.
• Fused, GFCI- equipped receptacle. I have a device consisting of a 1900 box, a faceplate accommodating a switch and duplex self-contained GFCI receptacle. In one of the knock-outs I have installed an AGI fuse holder that allows me to install a fuse of the correct value for the device to be tested whether it has an on-board fuse or not. This then, has a standard 3-wire line-cord which is plugged into the isolation transformer. Another level of protection - mostly for the device.
• Do not ever, under any conditions, work on a concrete floor of any nature, even above grade. Concrete is conductive. And loaded with conductive salts.
• It is acceptable to use an anti-static mat or wristband if working with sensitive components If and ONLY IF one is using an isolation transformer on every item plugged in on the bench.
Serious Work Done Here: Will do actual tear-down and repairs at the component level. Will test items in a partially dismantled state with exposed voltage sources all over the place. To the above, add:
• Metered Variac or Iso Variac: one with meters for current and voltage, with sufficient range to show very small increments – a very few watts or a very few volts. Something with a 4” Mirrored meter calibrated from 0 – 1 A and other similar fine ranges would be a good start.
• De-soldering tool. There are very good hand-held vacuum devices these days that may be a bit of a PITA to clean, but are otherwise very effective.
• Solder tip cleaner – you may already have this.
• Solder dispenser.
• Point-source light – something on either a gooseneck or similar that may be clamped to or near the work either with a clamp or magnet.
• Third-hand devices – A GOOD ONE!! Note the plural! Look up www.quadhands.com
The goal here, again, is bench safety.
Tooling: There are many sorts of tools that one may have an opportunity or need to acquire over the years. These are not directly safety related other than they could help one avoid blind alleys and false results. They include, but are not limited to, and are in no particular order:
• Specialized meters: I keep an LCR meter, an ESR meter, a digital transistor tester, and a frequency counter. Of that bunch, the ESR and transistor tester see the most use.
• Tube tester: I am blessed with a lab-grade device capable of matching. Few are. But the basics are SHORTS and GAS. That is enough for 90+ % of most applications. I also have one of those.
• Oscilloscope: Yes, I own one. In the 10 years that I have done so, I have needed it three (3) times – for which only it gave me the information I needed. Takes up a LOT of real-estate otherwise.
• Signal Tracer (Audio & RF): This will allow you to trace a signal through an amp, for instance, and pick up where it stops (or starts). There are also very neat signal injectors – tiny hand-held items) that do the job as well.
At Various Levels
I am not speaking to tooling – except in passing, with the reasoning. And I am not speaking to functions except as they affect safety. There will be a separate paragraph at the end that will touch on some tooling and reasoning for the same.
Most Basic Level: This would be for users that do the occasional kit assembly, occasional cleaning, but no substantive testing of equipment and no specific voltage checks or exposures to open circuitry. This individual *might* own a VOM, but generally would not use it for this work, except to do bias checks. Items on this bench would not be plugged in, except as fully-assembled devices in the final stages of testing and initial operation.
Safety:
• Clean, dry non-metallic work surface of sufficient area for good access and a clear view, and for all tools, parts and pieces to be used and/or placed without clutter.
• A non-conductive, comfortable chair with pivoting functions and, preferably arms.
• Lighting: Excellent lighting not only aids assembly, but is a significant safety feature in its own right. I suggest at least two articulated (architectural-type) lamps, one with a magnifier, if possible. This permits shadowless light as well.
• High-quality tools. All hand-tools such as screw-drivers, files, pliers, cutters, needle-nose, and so forth should be exclusively of US or Euro origin, without exception or discussion. If ever one has cut a high-tension wire with a Chinese tool and seen it vaporize and spread hot metal over a cubic foot of area, one will understand this instantly – and the hard way.
• Soldering Device: Something with variable power, but a minimum of 35 watts if fixed. Preferably with replaceable tips. And with a flat-blade IRON tip. It is better to use a hot iron for a short time than a cool one for a longer time.
• Eutectic Solder: 37/63 if lead/tin. 3-part Cu/SN/AG (very expensive) if RoHS compliant. ACCEPT NO SUBSTITUTES.
• Excellent ventilation: Solder flux, other smells and such are not good. Repeat – EXCELLENT ventilation.
Next Level: May do some actual testing. May do some troubleshooting, but consisting mostly of testing voltages and cleaning pots and jacks. But items may be PLUGGED IN and operating with exposed high-voltage parts. So, to the above add:
• ISOLATION TRANSFORMER: something capable of handling any anticipated load or piece of equipment you might need to test. This varies by the need, but should start at a minimum of 3A (Continuous) rating, to as many as one can afford. The purpose of this is to isolate you – the operator – from the local ground plane such that if you do touch a 525 V B+ node, you do not die.
• High end VOM: You will pay and pay and pay for a cheap device. Start with Fluke – and work down until you can afford it. But, really, try to stick with Fluke.
• Fused, GFCI- equipped receptacle. I have a device consisting of a 1900 box, a faceplate accommodating a switch and duplex self-contained GFCI receptacle. In one of the knock-outs I have installed an AGI fuse holder that allows me to install a fuse of the correct value for the device to be tested whether it has an on-board fuse or not. This then, has a standard 3-wire line-cord which is plugged into the isolation transformer. Another level of protection - mostly for the device.
• Do not ever, under any conditions, work on a concrete floor of any nature, even above grade. Concrete is conductive. And loaded with conductive salts.
• It is acceptable to use an anti-static mat or wristband if working with sensitive components If and ONLY IF one is using an isolation transformer on every item plugged in on the bench.
Serious Work Done Here: Will do actual tear-down and repairs at the component level. Will test items in a partially dismantled state with exposed voltage sources all over the place. To the above, add:
• Metered Variac or Iso Variac: one with meters for current and voltage, with sufficient range to show very small increments – a very few watts or a very few volts. Something with a 4” Mirrored meter calibrated from 0 – 1 A and other similar fine ranges would be a good start.
• De-soldering tool. There are very good hand-held vacuum devices these days that may be a bit of a PITA to clean, but are otherwise very effective.
• Solder tip cleaner – you may already have this.
• Solder dispenser.
• Point-source light – something on either a gooseneck or similar that may be clamped to or near the work either with a clamp or magnet.
• Third-hand devices – A GOOD ONE!! Note the plural! Look up www.quadhands.com
The goal here, again, is bench safety.
Tooling: There are many sorts of tools that one may have an opportunity or need to acquire over the years. These are not directly safety related other than they could help one avoid blind alleys and false results. They include, but are not limited to, and are in no particular order:
• Specialized meters: I keep an LCR meter, an ESR meter, a digital transistor tester, and a frequency counter. Of that bunch, the ESR and transistor tester see the most use.
• Tube tester: I am blessed with a lab-grade device capable of matching. Few are. But the basics are SHORTS and GAS. That is enough for 90+ % of most applications. I also have one of those.
• Oscilloscope: Yes, I own one. In the 10 years that I have done so, I have needed it three (3) times – for which only it gave me the information I needed. Takes up a LOT of real-estate otherwise.
• Signal Tracer (Audio & RF): This will allow you to trace a signal through an amp, for instance, and pick up where it stops (or starts). There are also very neat signal injectors – tiny hand-held items) that do the job as well.
peterh
