TIMESTAMPS BELOW 0:00 Introduction 0:51 Electrical safety 2:21 Connectors & probes I use when troubleshooting 4:51 What to look for when shopping for a multimeter - which functions are most important? 8:51 Plugging in probes - what is polarity and how much does it matter? 11:56 Opinion - most electrical theory videos are NOT presented with the repair person in mind 14:25 The difference between AC and DC 17:09 Ohm's Law - thinking of DC like water is helpful, but I don't do any calculations 21:03 Parallell circuits & why it is good to test components out of circuit 25:51 Voltage dividers & Ohm's law 29:38 Understanding voltage drop 32:43 How voltage drop impacts what we are doing with the Multimeter 35:21 Where I put the probes when measuring DC power supply to active components, voltage drop & resistance 37:04 Using a schematic to figure out where to put meter probes 39:00 Why I don't use my DMM's AC voltage function for troubleshooting power circuits 40:15 Why the DMM is unsuitable for some analogue signals 41:15 Why I use an audio probe or oscilloscope when troubleshooting audio signals 44:03 I can use DMM for amplifier & bias calibration, but often an oscilloscope is more convenient 45:17 What is a continuity test? Why do I find it so useful? 47:32 Continuity test example 1 - checking faders, switches, pots etc 49:31 Continuity test example 2 - checking coils... solenoids, relays, inductors, chokes, etc. 50:12 Continuity test example 3 - checking magnetic heads (be sure to degauss afterwards!) 50:49 Continuity test example 4 - checking cables and PCB traces 52:26 Continuity test example 5 - figuring out if/ which components are connected to ground 55:53 DC voltage measurement example 1 - checking an active component is receving power 59:56 DC voltage measurement example 2 - comparing voltage readings on a healthy & unhealthy circuit 1:02:20 DC voltage measurement example 3 - using DC voltage readings to identify a faulty semiconductor 1:03:36 Just enough theory on semiconductors to test them 1:06:27 Using the diode tester function to check semiconductors out of circuit 1:08:42 Sometimes it is more convenient to use a cheap component tester.... 1:10:47 I would a component tester to measure capacitance becasue it shows me ESR... 1:11:13 ...but in practice I just replace small value electrolytic capacitors 1:11:56 Checking resistor values & why it is usually the last thing I check 1:13:01 Comparing resistances on healthy & unhealthy circuits is a diagnostic tool but I use other methods 1:14:02 AC voltage reading example - testing for the presence of AC bias 1:15:16 AC voltage reading for playback amplifier calibration 1:16:47 For safety reasons I use voltage drop & continuity with the power off to troubleshoot PSUs 1:18:24 Frequency counter example - checking AC bias frequency 1:19:32 Conclusion
My multimeter came with no instructions. It's largely assumed online that we all just know how to use one. I do not. This guide was really helpful cheers
Thanks John. When I was figuring this stuff out I found the lack of basic information like this quite bizarre, especially considering how well much more advanced electronics topics are catered to! I hope I've gone some way to that gap, thanks for watching.
Hey Tetra - You were right this video was SUPER helpful. Definitely demystified a few things for me. I had a question and hope you would elaborate more on your cap replacement decision - around 1:10:00 you mention changing caps in an area that is having issues. Would you say on a smaller unit like a 2 track and simpler 4tracks like my own Mf-P01 that replacing ALL the capacitors is worthwhile rather than just the circuit you're working in that has the problem? Normally I assume this would be too time consuming when there's 100+ caps but in the case of the Mf-P01 there is a total of 48 electrolytic caps
Yeah I did that on a porta 03 recently. The counter argument is it can be a good learning experience to use rhe audio probe to narrow down where the issue is though?
Thank you, this video is very well made. I don't understand one thing, in the voltage divider example you show how measuring with the positive probe before any resistor and the negative probe connected to ground you would read for ex 9v, and then moving the positive probe after a resistor the voltage would have dropped. I thought that the "water pressure" (Volts) would increase after the "restricted pipe" (resistor) rather than decrease, what am I missing?
Hi Ed. The short answer is …. the water analogy bit of this video is badly explained, if not actually misleading, and I will need to replace it ASAP! By using the analogy of a pressure nozzle on a hose, a viewer could be forgiven for thinking that by adding more and more resistance to a circuit we can increase the voltage available from a battery or other voltage source, and I want to be clear, that is NOT true…A better analogy would be a pump representing a battery or other voltage source, attached to a pipe consisting of three wider sections divided by two narrower sections: In such a pipe then the first section (after the pump) has high pressure, the second section (after the first narrow section) would have lower pressure, and the third section (after the second narrow section) would have the lowest pressure of all. Thank you for watching, and for your valuable feedback!
You can use a DMM to ensure the oscillator in the 388 is producing the correct frequency, definitely. You could also use AC voltage setting to measure the amplitude of the bias signal at the heads. What might be missing is easily available or reliable information on what this voltage should be for different tape types. It's in my to-do list to investigate this and present my findings on the channel.
yeah I think you need a meter that gets to around the 150mv range, but I dunno what i'm talking about really. This video is great btw, thanks@@Tetrakan
TIMESTAMPS BELOW
0:00 Introduction
0:51 Electrical safety
2:21 Connectors & probes I use when troubleshooting
4:51 What to look for when shopping for a multimeter - which functions are most important?
8:51 Plugging in probes - what is polarity and how much does it matter?
11:56 Opinion - most electrical theory videos are NOT presented with the repair person in mind
14:25 The difference between AC and DC
17:09 Ohm's Law - thinking of DC like water is helpful, but I don't do any calculations
21:03 Parallell circuits & why it is good to test components out of circuit
25:51 Voltage dividers & Ohm's law
29:38 Understanding voltage drop
32:43 How voltage drop impacts what we are doing with the Multimeter
35:21 Where I put the probes when measuring DC power supply to active components, voltage drop & resistance
37:04 Using a schematic to figure out where to put meter probes
39:00 Why I don't use my DMM's AC voltage function for troubleshooting power circuits
40:15 Why the DMM is unsuitable for some analogue signals
41:15 Why I use an audio probe or oscilloscope when troubleshooting audio signals
44:03 I can use DMM for amplifier & bias calibration, but often an oscilloscope is more convenient
45:17 What is a continuity test? Why do I find it so useful?
47:32 Continuity test example 1 - checking faders, switches, pots etc
49:31 Continuity test example 2 - checking coils... solenoids, relays, inductors, chokes, etc.
50:12 Continuity test example 3 - checking magnetic heads (be sure to degauss afterwards!)
50:49 Continuity test example 4 - checking cables and PCB traces
52:26 Continuity test example 5 - figuring out if/ which components are connected to ground
55:53 DC voltage measurement example 1 - checking an active component is receving power
59:56 DC voltage measurement example 2 - comparing voltage readings on a healthy & unhealthy circuit
1:02:20 DC voltage measurement example 3 - using DC voltage readings to identify a faulty semiconductor
1:03:36 Just enough theory on semiconductors to test them
1:06:27 Using the diode tester function to check semiconductors out of circuit
1:08:42 Sometimes it is more convenient to use a cheap component tester....
1:10:47 I would a component tester to measure capacitance becasue it shows me ESR...
1:11:13 ...but in practice I just replace small value electrolytic capacitors
1:11:56 Checking resistor values & why it is usually the last thing I check
1:13:01 Comparing resistances on healthy & unhealthy circuits is a diagnostic tool but I use other methods
1:14:02 AC voltage reading example - testing for the presence of AC bias
1:15:16 AC voltage reading for playback amplifier calibration
1:16:47 For safety reasons I use voltage drop & continuity with the power off to troubleshoot PSUs
1:18:24 Frequency counter example - checking AC bias frequency
1:19:32 Conclusion
definitive guide! Great work, thanks
Thanks, hope it’s helpful!
this is so valuable man. thanks!
Glad it’s useful, thanks for watching!
My multimeter came with no instructions. It's largely assumed online that we all just know how to use one. I do not. This guide was really helpful cheers
Thanks John. When I was figuring this stuff out I found the lack of basic information like this quite bizarre, especially considering how well much more advanced electronics topics are catered to! I hope I've gone some way to that gap, thanks for watching.
thanks for doing this, Scotland
Well, we needed to do something good after inventing obesity and racism
good job, very useful, thanks
Thanks!
Hey Tetra - You were right this video was SUPER helpful. Definitely demystified a few things for me. I had a question and hope you would elaborate more on your cap replacement decision - around 1:10:00 you mention changing caps in an area that is having issues. Would you say on a smaller unit like a 2 track and simpler 4tracks like my own Mf-P01 that replacing ALL the capacitors is worthwhile rather than just the circuit you're working in that has the problem? Normally I assume this would be too time consuming when there's 100+ caps but in the case of the Mf-P01 there is a total of 48 electrolytic caps
Yeah I did that on a porta 03 recently. The counter argument is it can be a good learning experience to use rhe audio probe to narrow down where the issue is though?
@@Tetrakan Same page! I told myself I wouldn't do a complete replacement until I tracked the problem down so I get the experience of both
Thank you, this video is very well made. I don't understand one thing, in the voltage divider example you show how measuring with the positive probe before any resistor and the negative probe connected to ground you would read for ex 9v, and then moving the positive probe after a resistor the voltage would have dropped. I thought that the "water pressure" (Volts) would increase after the "restricted pipe" (resistor) rather than decrease, what am I missing?
Hi Ed. The short answer is …. the water analogy bit of this video is badly explained, if not actually misleading, and I will need to replace it ASAP! By using the analogy of a pressure nozzle on a hose, a viewer could be forgiven for thinking that by adding more and more resistance to a circuit we can increase the voltage available from a battery or other voltage source, and I want to be clear, that is NOT true…A better analogy would be a pump representing a battery or other voltage source, attached to a pipe consisting of three wider sections divided by two narrower sections: In such a pipe then the first section (after the pump) has high pressure, the second section (after the first narrow section) would have lower pressure, and the third section (after the second narrow section) would have the lowest pressure of all. Thank you for watching, and for your valuable feedback!
Could you use the Hz mode to bias a Tascam 338? Actually, would you ever do a biasing video?
You can use a DMM to ensure the oscillator in the 388 is producing the correct frequency, definitely. You could also use AC voltage setting to measure the amplitude of the bias signal at the heads. What might be missing is easily available or reliable information on what this voltage should be for different tape types. It's in my to-do list to investigate this and present my findings on the channel.
yeah I think you need a meter that gets to around the 150mv range, but I dunno what i'm talking about really. This video is great btw, thanks@@Tetrakan