Season greetings gents.
I just completed repair to a Stetsom HL1200.04 which had no voltage to pin 12 of the IRS2092 on both rear channels, this was troubleshooted and rectified, amplifier now passes clean audio.
however when connected to a speaker, the amplifier has a turn on and off thump. I wasn't sure if to post in the class D, but I'm looking at two avenues that may be causing the thump:
1. Does any of the capacitive components of the IRS2092 which control shutdown/mute/standby can be altered to overcome this, whilst the amplifier is being powered up and down?
2. I'm also looking at the remote turn on to the SG3525 and the soft start pin 8. can/will altering these values assist with or eliminate the turn on/off thump?
I haven't messed around much with IRS2092.
I just completed repair to a Stetsom HL1200.04 which had no voltage to pin 12 of the IRS2092 on both rear channels, this was troubleshooted and rectified, amplifier now passes clean audio.
however when connected to a speaker, the amplifier has a turn on and off thump. I wasn't sure if to post in the class D, but I'm looking at two avenues that may be causing the thump:
1. Does any of the capacitive components of the IRS2092 which control shutdown/mute/standby can be altered to overcome this, whilst the amplifier is being powered up and down?
2. I'm also looking at the remote turn on to the SG3525 and the soft start pin 8. can/will altering these values assist with or eliminate the turn on/off thump?
I haven't messed around much with IRS2092.
Attachments
Are all 4 channels doing this equally?
How bad is the pop (a light tick or the cone being blown out of the speaker frame)?
Are you sure that this isn't common to this model amp?
What are they using for muting, the CSD terminal?
If so, is the voltage ramping up as expected on the CSD terminal?
How bad is the pop (a light tick or the cone being blown out of the speaker frame)?
Are you sure that this isn't common to this model amp?
What are they using for muting, the CSD terminal?
If so, is the voltage ramping up as expected on the CSD terminal?
Are all 4 channels doing this equally?
Yes all four channels.
How bad is the pop (a light tick or the cone being blown out of the speaker frame)?
Its a very light tick
Are you sure that this isn't common to this model amp?
I'm not sure, I rarely get these Brazilian amps to work on, probably someone else can chime in.
What are they using for muting, the CSD terminal?
From looking at the data sheet and application note, the circuit is very similar and it seems to be the CSD pin.
If so, is the voltage ramping up as expected on the CSD terminal?
The voltage ramps up linear as what the AN has to 5.79vdc.
I removed the signal generator on the bench and wired up two different HU (Alpine and Kenwood) to see if the pop was associated with the input signals:
1: There is no turn on/off thump/pop with the Kenwood (aside the minor tick the amp does by itself)
2: There is a loud turn on/off thump/pop with the Alpine. I believe this to be similar to what the customer reported. He has a Pioneer HU. Manually applying remote to the amp doesn't produce any turn on/off thump/pop.
The guy said the audio in his car was not doing this prior to the repair, and I didn't do any work on the front channels, he hasn't done any modifications to his system while the amplifier is out.
Yes all four channels.
How bad is the pop (a light tick or the cone being blown out of the speaker frame)?
Its a very light tick
Are you sure that this isn't common to this model amp?
I'm not sure, I rarely get these Brazilian amps to work on, probably someone else can chime in.
What are they using for muting, the CSD terminal?
From looking at the data sheet and application note, the circuit is very similar and it seems to be the CSD pin.
If so, is the voltage ramping up as expected on the CSD terminal?
The voltage ramps up linear as what the AN has to 5.79vdc.
I removed the signal generator on the bench and wired up two different HU (Alpine and Kenwood) to see if the pop was associated with the input signals:
1: There is no turn on/off thump/pop with the Kenwood (aside the minor tick the amp does by itself)
2: There is a loud turn on/off thump/pop with the Alpine. I believe this to be similar to what the customer reported. He has a Pioneer HU. Manually applying remote to the amp doesn't produce any turn on/off thump/pop.
The guy said the audio in his car was not doing this prior to the repair, and I didn't do any work on the front channels, he hasn't done any modifications to his system while the amplifier is out.
Is the shield ground intact on the Alpine?
Does the Alpine have any noise that should be muted when changing stations or tracks on the CD (if it has a CD player)?
Does the Alpine have any noise that should be muted when changing stations or tracks on the CD (if it has a CD player)?
I checked this, the shield is grounded and it doesn't have any noise tuner or CD.
the stetsom measured 1kohm from RCA shield to negative on power terminal.
the stetsom measured 1kohm from RCA shield to negative on power terminal.
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Does the alpine cause the same noise on other amps?
The reason I ask is because the muting transistors should clamp all noise when powering up, especially if the shield ground is intact.
I think I'd try to find out whether this is a common issue with these amps before doing any more troubleshooting.
As a side note, I'd suggest checking the shield grounds on the customer's Pioneer. Many had problems with blown shield ground fuses.
The reason I ask is because the muting transistors should clamp all noise when powering up, especially if the shield ground is intact.
I think I'd try to find out whether this is a common issue with these amps before doing any more troubleshooting.
As a side note, I'd suggest checking the shield grounds on the customer's Pioneer. Many had problems with blown shield ground fuses.