They are Zener diodes. The markings tell you the rated voltage. You'll have to measure them with a dial caliper to get the correct case style.
It's impossible to tell if the drive is good on AC coupling. Do you have two probes?
Do you know how to use your scope in differential mode?
Do you know how to use your scope in differential mode?
A differential input uses two inputs to produce a single waveform. The simplest way to get a differential input is to use a differential probe. A differential probe has two signal leads and a mixer amplifier built into it. It feeds the scope a normal signal (a composite of the two signals input into the differential probe). The problem with differential probes is that they're expensive.
The alternative is to use two scope probes and and both inputs of your oscilloscope. This is how you have to set up your scope:
Two probes
Both scope inputs used
Input set to add
Both channels set to DC coupling
Both channels set to 'cal'.
Both vertical amps set to the same voltage
Ch2 input set to invert
Bandwidth limited (works best for most measurements in car amps)
Trace aligned to the reference line on the scope's display
Ground leads for both probes connected together (not always necessary)
After setting up the scope, you need to confirm that it's working as it should. With the vertical amp set to 5v/div, touching the probe that's connected to Ch1 to the positive terminal of your 12v power supply should make the trace deflect about 2.5 divisions up from the reference (like it always does, seen below). Doing the same with the probe connected to Ch2 should make the trace deflect down about 2.5 divisions. Touching both probes to the positive terminal of the 12v power supply should cause no deflection. If it does, something isn't right.
I know that this may not be as simple as the isolated scope but if you take the time to learn it one time (even if it takes an hour or more of your time)N, you have that knowledge and this tool to use for the rest of the time you need to use a scope. Using the analog scope will give you much larger and cleaner waveforms.
The alternative is to use two scope probes and and both inputs of your oscilloscope. This is how you have to set up your scope:
Two probes
Both scope inputs used
Input set to add
Both channels set to DC coupling
Both channels set to 'cal'.
Both vertical amps set to the same voltage
Ch2 input set to invert
Bandwidth limited (works best for most measurements in car amps)
Trace aligned to the reference line on the scope's display
Ground leads for both probes connected together (not always necessary)
After setting up the scope, you need to confirm that it's working as it should. With the vertical amp set to 5v/div, touching the probe that's connected to Ch1 to the positive terminal of your 12v power supply should make the trace deflect about 2.5 divisions up from the reference (like it always does, seen below). Doing the same with the probe connected to Ch2 should make the trace deflect down about 2.5 divisions. Touching both probes to the positive terminal of the 12v power supply should cause no deflection. If it does, something isn't right.
I know that this may not be as simple as the isolated scope but if you take the time to learn it one time (even if it takes an hour or more of your time)N, you have that knowledge and this tool to use for the rest of the time you need to use a scope. Using the analog scope will give you much larger and cleaner waveforms.
Hi Perry, was about to try this but now I'm not getting any drive signals. The lm319 seems to be heating up. Not sure if the tl072 and lm319 have gone bad. Rail voltages are present and I have both +12v and -12v present.
How hot, how fast?
Hotter than the TL072?
Do you have a replacement IC?
Connect a speaker/dummy load across the speaker terminals. Does that make a difference (in the drive signal)?
You can still get the differential setup done, even if there are other problems.
Hotter than the TL072?
Do you have a replacement IC?
Connect a speaker/dummy load across the speaker terminals. Does that make a difference (in the drive signal)?
You can still get the differential setup done, even if there are other problems.
Hi Perry,
I've replaced both ICS but still no drive signals.
I have a square wave on pin7 of the lm319 but nothing on pin12
on which pin is the audio signal on the driver board?
I've replaced both ICS but still no drive signals.
I have a square wave on pin7 of the lm319 but nothing on pin12
on which pin is the audio signal on the driver board?
https://www.diyaudio.com/community/threads/again-with-the-dlogixs-dlm4500.299926/post-6947617
On the dlogix_4500_schb.pdf diagram above, confirm that you have all of the supply voltages.
Is the LM319 heating up after replacing it?
On the dlogix_4500_schb.pdf diagram above, confirm that you have all of the supply voltages.
Is the LM319 heating up after replacing it?
Hi Perry, not heating up...
the dual probe setup showed a difference in the drive signals...
could it be a bad cap or resistor?
please see below:
the dual probe setup showed a difference in the drive signals...
could it be a bad cap or resistor?
please see below:
Yes, I think so. I followed your instructions
by differences I mean the shape of the signals, not completely square
by differences I mean the shape of the signals, not completely square
Check the calibration by touching the probe to the scope's test signal.
Do you have any capacitors in the area of 1000pf?
Do you have any capacitors in the area of 1000pf?