GD Folks,
I’m having a problem with IRS2092/CSC3120 oscillating.
Over the past couple of weeks, I got in a couple of DS18 CandyX5B and a Taramps TS600x4. Each amplifier displays the same failure mode.
The DS18 5CH, employs either IRS2092 or CSC3120 for the sub channel, the Taramps uses IRS2092 for all four channels.
Taramps; shorted outputs in three channels, replaced IRS2092 and output FETs, two of the three channels powered up ok, good R-R oscillation, however the third channel appears like it wants to start R-R oscillation, zooming on the scope it does have sq waves before it flatlines and it repeats this until the unit is turned off.
DS18 X5B; 3 units came in, each with similar reports of sub channel not working. One unit uses CSC3120 and the other 2, IRS2092. Each unit appears like it wants to start R-R oscillation, zooming on the scope it does have sq waves before it flatlines and it repeats this.
Thus far I’ve only messed with the DS18 with the CSC3120, I’ve replaced it with a new IRS2092, and used various values of caps for pin 4 to alter the oscillating freq, I’ve measured the resistors around pins 7 and 8, both are with spec. I’ve compared these values with the other two DS18 amplifiers, measured and all measure around the same resistance.
In the one unit I messed with, I replaced the resistors with new. All to no avail, the unit remains the same and shows as if it is trying to start oscillating. All other components around the FETs/output of the drivers are testing ok.
I’ve attached a couple of scope screen captures to aid with my description of what’s happening. Anyone ever saw something similar and remedied it?
I’m having a problem with IRS2092/CSC3120 oscillating.
Over the past couple of weeks, I got in a couple of DS18 CandyX5B and a Taramps TS600x4. Each amplifier displays the same failure mode.
The DS18 5CH, employs either IRS2092 or CSC3120 for the sub channel, the Taramps uses IRS2092 for all four channels.
Taramps; shorted outputs in three channels, replaced IRS2092 and output FETs, two of the three channels powered up ok, good R-R oscillation, however the third channel appears like it wants to start R-R oscillation, zooming on the scope it does have sq waves before it flatlines and it repeats this until the unit is turned off.
DS18 X5B; 3 units came in, each with similar reports of sub channel not working. One unit uses CSC3120 and the other 2, IRS2092. Each unit appears like it wants to start R-R oscillation, zooming on the scope it does have sq waves before it flatlines and it repeats this.
Thus far I’ve only messed with the DS18 with the CSC3120, I’ve replaced it with a new IRS2092, and used various values of caps for pin 4 to alter the oscillating freq, I’ve measured the resistors around pins 7 and 8, both are with spec. I’ve compared these values with the other two DS18 amplifiers, measured and all measure around the same resistance.
In the one unit I messed with, I replaced the resistors with new. All to no avail, the unit remains the same and shows as if it is trying to start oscillating. All other components around the FETs/output of the drivers are testing ok.
I’ve attached a couple of scope screen captures to aid with my description of what’s happening. Anyone ever saw something similar and remedied it?
Attachments
Perhaps an open resistor (or severely increased in value) turned the amp into a blocking oscillator.
#2: With the DS18 amps I've measured and compared values between amps, all are about the same give or take a couple of ohms.
With the Taramps, I measured and compared with the nearby channels.
#3: only the Taramps had shorted output FETs (IRFB4019), these were replaced with new from Mouser, for the three defective channels, of the three repaired channels, one is displaying this attempt at start up.
On the DS18 with the CSC3120, the output FETs (SVT20240NT) tested ok both in and out of circuit. I replaced the 3120 with a new 2092, after checking resistors, i replaced the SVT20240NT FETs with IRFB4019. All changes were to no avail.
With the Taramps, I measured and compared with the nearby channels.
#3: only the Taramps had shorted output FETs (IRFB4019), these were replaced with new from Mouser, for the three defective channels, of the three repaired channels, one is displaying this attempt at start up.
On the DS18 with the CSC3120, the output FETs (SVT20240NT) tested ok both in and out of circuit. I replaced the 3120 with a new 2092, after checking resistors, i replaced the SVT20240NT FETs with IRFB4019. All changes were to no avail.
The other channels in the taramps are oscillating around 400khz.
I looked at older DS18 amps I repaired, and the sub channel is also around 400khz.
The first pic is from the Taramps, and the second an older DS18 amp sub channel.
From looking at the IRS2092 application note and resistor values for pin 4, around 400Khz seems about right.
I looked at older DS18 amps I repaired, and the sub channel is also around 400khz.
The first pic is from the Taramps, and the second an older DS18 amp sub channel.
From looking at the IRS2092 application note and resistor values for pin 4, around 400Khz seems about right.
Attachments
Is CSD voltage the same as the other ICs?
Do you have audio reaching the input of the dead channel?
DCV across pins 10 and 12?
DCV across pins 13 and 15? You may have to connect to these before startup. Connection to the high-side filter cap may be easier than pins 13 and 15.
Do you have audio reaching the input of the dead channel?
DCV across pins 10 and 12?
DCV across pins 13 and 15? You may have to connect to these before startup. Connection to the high-side filter cap may be easier than pins 13 and 15.
I have the DS18 with the CSC3120 replaced with a IRS2092 and IRFB4019 FETS on the bench presently. the measurements are from this unit.
Is CSD voltage the same as the other ICs? I have these written down from troubleshooting; 4.86v, this DS18 measures 7.28v
Do you have audio reaching the input of the dead channel? Yes
DCV across pins 10 and 12? 11.71v
DCV across pins 13 and 15? You may have to connect to these before startup. Connection to the high-side filter cap may be easier than pins 13 and 15. 8.75v
Is CSD voltage the same as the other ICs? I have these written down from troubleshooting; 4.86v, this DS18 measures 7.28v
Do you have audio reaching the input of the dead channel? Yes
DCV across pins 10 and 12? 11.71v
DCV across pins 13 and 15? You may have to connect to these before startup. Connection to the high-side filter cap may be easier than pins 13 and 15. 8.75v
Is the pin 13-15 lower than the other working channels?
I don't understand the following. Please explain in more detail:
Is CSD voltage the same as the other ICs? I have these written down from troubleshooting; 4.86v, this DS18 measures 7.28v
Does the DS18 use the 2092 for all 5 channels?
The same output FETs for all 5 channels?
If the attached diagram is the same as your taramps amplifiers, start a new thread for it alone.
I don't understand the following. Please explain in more detail:
Is CSD voltage the same as the other ICs? I have these written down from troubleshooting; 4.86v, this DS18 measures 7.28v
Does the DS18 use the 2092 for all 5 channels?
The same output FETs for all 5 channels?
If the attached diagram is the same as your taramps amplifiers, start a new thread for it alone.
Yes, the attached schematic is similar to the taramps I have.
The DS18 is a 5channel amplifier, it uses 2 TDA8954 (post 1) for the 4 full range channels, and a IRS2092/ CSC3120 with FETs (IRFB4019) for the sub channel.
The measurements referenced in posts above are all from the DS18.
The DS18 is a 5channel amplifier, it uses 2 TDA8954 (post 1) for the 4 full range channels, and a IRS2092/ CSC3120 with FETs (IRFB4019) for the sub channel.
The measurements referenced in posts above are all from the DS18.