Everyone check out this setup! I built this workstation, which also has a table/desk underneath. I'm about 90% finished; just waiting for my Oscilloscope, and some electrical stuff like distribution blocks, RCAs, 1000w resistor packs. I was also thinking of putting some more volt meters and amp meters around for monitoring things during operation. Especially on the high amperage 12vDC side.
Ive been working on this bench for about 2 days. My goal was to create a compact space in which nothing but just the amplifier<s> I'm working with will sit on the countertop to hopefully and greatly reduce clutter. Everything else is hung up or sitting on a shelf above/below. I wired some of the outlets to switches and such so that equipment can be shut down when not in use etc. GFI outlet is constant which supplies 110vAC to the rest mainly controlled by switches and also ground fault protected.
Then the 12vDB components are protected at the main power supply using 60A fuse and a 200A main breaker. This can be upgraded later on as well. The setup can provide up to a few hundred amps burst, as well as fine tuning control during repair and such with a OVP/OCP 0-5A and soon a 0-20A supply.
The radio will be used as a test source and also for ambient audio. I wired the speakers to be switchable between the radio's built-in or the bench amplifier so I can play some audio while working, hit a switch and output from the amp to the speakers. Banana plugs, distribution blocks, RCAs will be in front, and wring is all on the back mostly hidden except for what to be used for hookup to the amps, and of course device probes. The Hako solder station is actually well positioned and long enough to solder anywhere on the bench as well.
The rubber mats are grooved and just floor matts from Lowes. I like the grooves because if a piece of and bits of wire happen to fall, they fall into the grooves and won't make contact with the work. Plus its easy on the amps and very comfortable.
Very excited. Hope to keep it
Ive been working on this bench for about 2 days. My goal was to create a compact space in which nothing but just the amplifier<s> I'm working with will sit on the countertop to hopefully and greatly reduce clutter. Everything else is hung up or sitting on a shelf above/below. I wired some of the outlets to switches and such so that equipment can be shut down when not in use etc. GFI outlet is constant which supplies 110vAC to the rest mainly controlled by switches and also ground fault protected.
Then the 12vDB components are protected at the main power supply using 60A fuse and a 200A main breaker. This can be upgraded later on as well. The setup can provide up to a few hundred amps burst, as well as fine tuning control during repair and such with a OVP/OCP 0-5A and soon a 0-20A supply.
The radio will be used as a test source and also for ambient audio. I wired the speakers to be switchable between the radio's built-in or the bench amplifier so I can play some audio while working, hit a switch and output from the amp to the speakers. Banana plugs, distribution blocks, RCAs will be in front, and wring is all on the back mostly hidden except for what to be used for hookup to the amps, and of course device probes. The Hako solder station is actually well positioned and long enough to solder anywhere on the bench as well.
The rubber mats are grooved and just floor matts from Lowes. I like the grooves because if a piece of and bits of wire happen to fall, they fall into the grooves and won't make contact with the work. Plus its easy on the amps and very comfortable.
Very excited. Hope to keep it
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, 2 - you probably need to wear knee-protectors ...
One gizmo I keep on one of my benches is a high power loudspeaker attenuator. It is a constant impedance load of 8 ohms on the amplifier but has 12 steps to drop the loudspeaker level. It uses high power resistors connected to a heat sink. Very nicely allows full power testing of amplifiers while keeping an ear on things. Much faster than just a dummy load and an analyzer. Also provides protection for the bench loudspeakers.
Of course you can also protect the test loudspeakers with fuses.
Other handy meter is one on the AC mains line to be sure a large amplifier is not causing it to sag.
Mandatory item is a light bulb box. On the bench I use switched ones to select the power limit from three lamps. Allows 25 W, 40 W, 65 W, 200 W, 225 W, 240 W and 265 W limits. I also have a 500 W photo flood lamp that can be changed in when doing larger amplifiers.
Of course you can also protect the test loudspeakers with fuses.
Other handy meter is one on the AC mains line to be sure a large amplifier is not causing it to sag.
Mandatory item is a light bulb box. On the bench I use switched ones to select the power limit from three lamps. Allows 25 W, 40 W, 65 W, 200 W, 225 W, 240 W and 265 W limits. I also have a 500 W photo flood lamp that can be changed in when doing larger amplifiers.
So you use the light box for high power testing was well? At 250-500w, even if the amp shorts and the light limits the current... thats still a LOT of power going through an amp. I'd expect then to probably blow some parts right?
I do have a single lightbulb but currently only have it for the low amperage side. I'm working with 12v audio here, which can pull 100s of amps. I do need to figure that one out though. I have some 1000w 4-ohm resistors coming in.
I do have a single lightbulb but currently only have it for the low amperage side. I'm working with 12v audio here, which can pull 100s of amps. I do need to figure that one out though. I have some 1000w 4-ohm resistors coming in.
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Hi Dr Zeus,
One thing I would add would be 4 ohm dummy loads (you're doing car amps, not home amps right?).
You absolutely need an oscilloscope (20 MHz is fine), and I would recommend an analogue, dual trace scope, not a digital one (which would be 100 MHz minimum, and hopefully 12 bit vertical). An oscillator is very handy and you can make one, or buy an older analogue one (I would go that route). But don't skimp on the multi-meter. A good bench one will make your life easier, and you can't afford to have your instruments lie to you.
A variable single polarity 15 volt (about) DC supply good for high current will allow you to test all kinds of things. A variable bipolar supply will allow you to bring up the amp sections slowly so you can troubleshoot at reduced voltages without the main switching supply (it comes up to full power right away).
I strongly believe in using a variac for bringing up line operated equipment over a light bulb. With the light bulb, your applied voltage is not defined, and you can get into strange interactions between the equipment under test and the light bulb and its variable resistance depending on load characteristic. But you aren't working on line operated equipment anyway are you?
Add a bright desk lamp with an arm and maybe a magnifier. But you have a nice setup there. I can't stress how important a 'scope and good meter are. As for the clamp meter, they are not very accurate. I am a certified Journeyman test equipment calibration technician. I also have 40 + years in the audio service field and can answer some questions you may have.
If you really do need a clamp meter, what I use are the Hewlett Packard 428A and Fluke AM 503 amplifier and a Fluke A6302 probe (use with 'scope), and I recently bought a Keysight 13434A probe for use with a multi-meter. These are expensive even used, but if you need a clamp probe, maybe these are the right answer. Certainly get them used if you can as the Keysight was around $750 Canadian I think. I also recently bought a Chinese clamp probe used with a 'scope, but they shipped it with the wrong plug and it looks like I am SOL. I can't tell you anything about reliability yet.
Clamp probes are really variable in their readings depending on where the conductor is in the loop area (in the clamp). Also, the ends of the clamp must be clean and come together exactly to take a reading. The expensive probes have a smaller area for the wire and are generally much less sensitive to the wire position. I have good clamp meters and they are nowhere near as accurate or repeatable in readings as the other ones I have listed. I would have to say that the best performance / dollar by far will be the HP 428A. It is a tube based unit made until the mid 80's and remains a favorite tool of mine. So if you want an accurate meter (self contained), this is by far the most accurate and best value per buck. They are good up to 10 amperes FS, which will do for you unless you run the amplifier under power on the primary side. If you buy one, be sure to get the meter with the probe (they are calibrated together). If you are going to buy a clamp type meter or probe, I highly recommend you buy one of these first.
For a multi-meter, I highly recommend a Fluke or Keysight. If you can find older HP 974A meters BUY ONE!!! An old Fluke 87 would also be ideal. BTW, Keysight = Agilent = HP, the company was split and Keysight is now the actual test and measurement section of the older HP (now into computers) brand. Agilent now does medical instruments. Do avoid Extech. Great specs but do not hold calibration well. This is where Keysight and Fluke really shine, and I know you are not going to calibrate your equipment every few years. So get stuff that tends to remain in calibration for years. My 974As are still in cal (0.05% basic DC accuracy) and compare to my new Keysight U1273A meter. The new meter has cool features, but the older 974A is still the one I like. I also have a Fluke 85, a nice meter you can trust. Also, the AC accuracy on these meters goes up to 100 KHz, most other meters are not accurate by 1 KHz!
I hope that wasn't too much info, but I will try to help you out. Your nice setup deserves good equipment - and so do you. It will save you a lot of time and false diagnoses.
-Chris
One thing I would add would be 4 ohm dummy loads (you're doing car amps, not home amps right?).
You absolutely need an oscilloscope (20 MHz is fine), and I would recommend an analogue, dual trace scope, not a digital one (which would be 100 MHz minimum, and hopefully 12 bit vertical). An oscillator is very handy and you can make one, or buy an older analogue one (I would go that route). But don't skimp on the multi-meter. A good bench one will make your life easier, and you can't afford to have your instruments lie to you.
A variable single polarity 15 volt (about) DC supply good for high current will allow you to test all kinds of things. A variable bipolar supply will allow you to bring up the amp sections slowly so you can troubleshoot at reduced voltages without the main switching supply (it comes up to full power right away).
I strongly believe in using a variac for bringing up line operated equipment over a light bulb. With the light bulb, your applied voltage is not defined, and you can get into strange interactions between the equipment under test and the light bulb and its variable resistance depending on load characteristic. But you aren't working on line operated equipment anyway are you?
Add a bright desk lamp with an arm and maybe a magnifier. But you have a nice setup there. I can't stress how important a 'scope and good meter are. As for the clamp meter, they are not very accurate. I am a certified Journeyman test equipment calibration technician. I also have 40 + years in the audio service field and can answer some questions you may have.
If you really do need a clamp meter, what I use are the Hewlett Packard 428A and Fluke AM 503 amplifier and a Fluke A6302 probe (use with 'scope), and I recently bought a Keysight 13434A probe for use with a multi-meter. These are expensive even used, but if you need a clamp probe, maybe these are the right answer. Certainly get them used if you can as the Keysight was around $750 Canadian I think. I also recently bought a Chinese clamp probe used with a 'scope, but they shipped it with the wrong plug and it looks like I am SOL. I can't tell you anything about reliability yet.
Clamp probes are really variable in their readings depending on where the conductor is in the loop area (in the clamp). Also, the ends of the clamp must be clean and come together exactly to take a reading. The expensive probes have a smaller area for the wire and are generally much less sensitive to the wire position. I have good clamp meters and they are nowhere near as accurate or repeatable in readings as the other ones I have listed. I would have to say that the best performance / dollar by far will be the HP 428A. It is a tube based unit made until the mid 80's and remains a favorite tool of mine. So if you want an accurate meter (self contained), this is by far the most accurate and best value per buck. They are good up to 10 amperes FS, which will do for you unless you run the amplifier under power on the primary side. If you buy one, be sure to get the meter with the probe (they are calibrated together). If you are going to buy a clamp type meter or probe, I highly recommend you buy one of these first.
For a multi-meter, I highly recommend a Fluke or Keysight. If you can find older HP 974A meters BUY ONE!!! An old Fluke 87 would also be ideal. BTW, Keysight = Agilent = HP, the company was split and Keysight is now the actual test and measurement section of the older HP (now into computers) brand. Agilent now does medical instruments. Do avoid Extech. Great specs but do not hold calibration well. This is where Keysight and Fluke really shine, and I know you are not going to calibrate your equipment every few years. So get stuff that tends to remain in calibration for years. My 974As are still in cal (0.05% basic DC accuracy) and compare to my new Keysight U1273A meter. The new meter has cool features, but the older 974A is still the one I like. I also have a Fluke 85, a nice meter you can trust. Also, the AC accuracy on these meters goes up to 100 KHz, most other meters are not accurate by 1 KHz!
I hope that wasn't too much info, but I will try to help you out. Your nice setup deserves good equipment - and so do you. It will save you a lot of time and false diagnoses.
-Chris
Thank you Chris, this is all very helpful.
Yes I have a 30Mhz BK Precision scope just not in the picture. There are 3 lights currently. 1. Light under the upper shelf has different intensities and colors selectable. It was a cheaper LED light but I like it. 2. Shop lights. 3. I have an LED magnified light/solder station. You can see it sitting on the top of the whole desk currently.
My smaller PSs have voltage and amperage control with cut-off for over-current protection. I also have a lightbulb I can use for if I'm trying to locate/isolate troubled stuff. On the higher amperage side I need some.
Yes I have a 30Mhz BK Precision scope just not in the picture. There are 3 lights currently. 1. Light under the upper shelf has different intensities and colors selectable. It was a cheaper LED light but I like it. 2. Shop lights. 3. I have an LED magnified light/solder station. You can see it sitting on the top of the whole desk currently.
My smaller PSs have voltage and amperage control with cut-off for over-current protection. I also have a lightbulb I can use for if I'm trying to locate/isolate troubled stuff. On the higher amperage side I need some.
You have a great start happening. If your B&K is dual trace, you're all sorted there.
If you can afford an Agilent or HP 34401A meter, get one used. They were just discontinued recently (a few years ago). That meter will save you huge amounts of time and really help you troubleshoot. I used them and bought one when they were first introduced. Almost the best meter I ever bought, I recently bought a 34465A, which I really love even more, but I still use my 34401A meters and enjoy them too.
There is a very good reason why these were industry standard meters in many industries. We even used them in the calibration lab I worked in. Of course, a much more expensive meter was used for calibration and as a standard ... the HP 3458A, but the little 34401A had its place and was used for calibrating other instruments. It is probably the best meter for use in service going, except for the newer series Keysight has out.
Anyway, grab a 34401A if you can. They do sell new displays on Ebay for them too (not exactly the same, but they work well). I have replaced a couple displays now since my 34401A's are so old now.
-Chris
If you can afford an Agilent or HP 34401A meter, get one used. They were just discontinued recently (a few years ago). That meter will save you huge amounts of time and really help you troubleshoot. I used them and bought one when they were first introduced. Almost the best meter I ever bought, I recently bought a 34465A, which I really love even more, but I still use my 34401A meters and enjoy them too.
There is a very good reason why these were industry standard meters in many industries. We even used them in the calibration lab I worked in. Of course, a much more expensive meter was used for calibration and as a standard ... the HP 3458A, but the little 34401A had its place and was used for calibrating other instruments. It is probably the best meter for use in service going, except for the newer series Keysight has out.
Anyway, grab a 34401A if you can. They do sell new displays on Ebay for them too (not exactly the same, but they work well). I have replaced a couple displays now since my 34401A's are so old now.
-Chris
I'll keep a tab on that meter... Seems to be a budget breaker though.
I am going to pick up a second DVM later today - actually a Klein Tools CL390 to be exact. Reviews online and videos etc seem to work well with 12vDC amperage reads. It does have a DC specific amperage clamp and other great features like temerature and frequency reading to offset my Fluke 16 (Perhaps replace it not sure). In honesty 10 years ago I was actually able to fix 90% of amplifiers with a Fluke 10, Ramsey scope, frequency generator etc... I'm re-building for better though. This is a hobby not a business and to buy all this equipment is already pretty money hungry. I also need one of those trigger soldering irons for quick things like wires and large terminal jobs, and eventually a better de-soldering station. Lots to do!
I am going to pick up a second DVM later today - actually a Klein Tools CL390 to be exact. Reviews online and videos etc seem to work well with 12vDC amperage reads. It does have a DC specific amperage clamp and other great features like temerature and frequency reading to offset my Fluke 16 (Perhaps replace it not sure). In honesty 10 years ago I was actually able to fix 90% of amplifiers with a Fluke 10, Ramsey scope, frequency generator etc... I'm re-building for better though. This is a hobby not a business and to buy all this equipment is already pretty money hungry. I also need one of those trigger soldering irons for quick things like wires and large terminal jobs, and eventually a better de-soldering station. Lots to do!
True, however I've often seen DC voltage across amplifier inputs say if an OpAmp or other circuit goes belly-up, or a voltage regulator dips etc, or center tap (RCA shield) goes floating away. I guess I could put a DC volt meter across the RCA jacks to measure this, but its not a very common concern - only when it happens, smokes your source. I do check this with my DVM but sometimes don't catch everything before "puff the magic dragon".
I had an old laptop being used as a signal source and such, and ended up actually frying the sound card in the laptop. I'd rather put that abuse against my WaveTek frequency generator, or the crappy $30 bench test head unit. The head unit does BlueTooth and so I can send whatever song or signal I want down into the amps.
I had an old laptop being used as a signal source and such, and ended up actually frying the sound card in the laptop. I'd rather put that abuse against my WaveTek frequency generator, or the crappy $30 bench test head unit. The head unit does BlueTooth and so I can send whatever song or signal I want down into the amps.
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Updated workspace photo. Loving this setup! And the main bench surface has been staying fairly clear. I can actually stack up about ~10 devices in service below the workbench at one time. Box on the bottom is parts equipment. Now I need to figure out where to put my HP 34401A, and also need to upgrade the main PS to 200A or more.
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Hi Dr. Zeus,
Nice setup. I would have mounted the scope where your stations are now, and the stations elsewhere, maybe under the bench. The 34401A should go up near the scope, because you will be looking at those two when troubleshooting.
Back when I serviced car audio only (1983 ish), it was possible to use a small, efficient bench that you could keep clean. Enjoy!
-Chris
Nice setup. I would have mounted the scope where your stations are now, and the stations elsewhere, maybe under the bench. The 34401A should go up near the scope, because you will be looking at those two when troubleshooting.
Back when I serviced car audio only (1983 ish), it was possible to use a small, efficient bench that you could keep clean. Enjoy!
-Chris
Yup, some LED as well. I had to move a fixture from my bench area. The ones I am using now output noise just north of 50 KHz. I am used to it and ignore it in LF frequency sweeps.
On great check is to turn lights and some instruments off when something funny is going on. For example, my nice Philips PM3070 scope can't co-exist with FM tuners. Same for the PM 3365. The trace on the Tektronix 2246B CT isn't very sharp, so isn't good for servicing CD players or low level signals. I ended up having to get a Keysight MSOX3104T in order to satisfy all requirements. The Philips still has the best, sharpest trace, the Keysight has the next best trace without taking FM tuners off the air.
So when you have funny stuff going on, nothing is beyond suspicion. Lights are #1 though.
-Chris
On great check is to turn lights and some instruments off when something funny is going on. For example, my nice Philips PM3070 scope can't co-exist with FM tuners. Same for the PM 3365. The trace on the Tektronix 2246B CT isn't very sharp, so isn't good for servicing CD players or low level signals. I ended up having to get a Keysight MSOX3104T in order to satisfy all requirements. The Philips still has the best, sharpest trace, the Keysight has the next best trace without taking FM tuners off the air.
So when you have funny stuff going on, nothing is beyond suspicion. Lights are #1 though.
-Chris
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I need a proper bench, have been in this hobby for at least a decade and still no proper bench - you have given me some ideas!
Yup, it's irrelevant how big your bench starts out, it can be huge - doesn't matter, you will end up with only enough space for a small PCB - it just is always that way.
Yup, it's irrelevant how big your bench starts out, it can be huge - doesn't matter, you will end up with only enough space for a small PCB - it just is always that way.
Haha same here! Every once in a while I spend one or two LOOONG nights tidying up and I marvel at it's beauty. Only to have it messy again before the next project is even looking like a project. (I always get several projects in the same area no matter what).