Hey Perry,
Prior to me loosing the good channel, the jumper trick didn't make a difference on the bad channel. I did smoke 2 of the "good" channels outputs (Q5 & Q6)... I think my test leads with gator clips to the speakers shorted! DOH! Anyhow, all outputs and voltages test ok now...heat is not present either. I sure would kill for an OScope right now! I suspect the 540's on the positive rail of both channels aren't kicking.
Where to go from here, I wonder?
Thank you again
Prior to me loosing the good channel, the jumper trick didn't make a difference on the bad channel. I did smoke 2 of the "good" channels outputs (Q5 & Q6)... I think my test leads with gator clips to the speakers shorted! DOH! Anyhow, all outputs and voltages test ok now...heat is not present either. I sure would kill for an OScope right now! I suspect the 540's on the positive rail of both channels aren't kicking.
Where to go from here, I wonder?Thank you again
You won't have any output through a bridged speaker when both channels are fed from the same signal source (right channel jumped to the left channel).
Both channels are distorted now?
Do you have any way to listen to the preamp signal? An old home receiver can be used to amplify the preamp signal. It would be nice to know if the preamp signal is the problem or if it's the power amp section.
Do you have a spare potentiometer (5k-100k ohm)?
Both channels are distorted now?
Do you have any way to listen to the preamp signal? An old home receiver can be used to amplify the preamp signal. It would be nice to know if the preamp signal is the problem or if it's the power amp section.
Do you have a spare potentiometer (5k-100k ohm)?
Any port in a storm! How bout this... I've got the other 150 freshly repaired and playing great. I suppose I could use it to amplify the pre-out signal of the problem 150... Wow, you are awesome Perry! Cool and simple troubleshooting methodology! I like it.
I do have a pot...what do ya have in mind?
I do have a pot...what do ya have in mind?
Let's not risk damaging the other amp.
Connect the potentiometer as shown to the two 15v voltage regulators. The output is on pin 3 of each regulator (confirm that you read plus/minus 15v on those pins before making the connections). Power up the amp and confirm that the voltage on the wiper terminal of the pot swings to ±15v. Set the shaft of the potentiometer to its center position. Connect the wiper of the pot to pin 3 of the driver board.
Connect the black probe of the multimeter to the ground terminal of the amplifier. Connect the red probe to the left + terminal when testing the left channel. Connect the red probe to the right - terminal when testing the right channel. SLOWLY rotate the shaft of the potentiometer about 45° from the center position while watching the DC voltage on the multimeter.
It would be better (safer) if the input capacitors (C9 and C10) from both channels were removed.
Does the DC voltage on the speaker terminal go positive when you rotate it one direction and negative when you rotate it the other direction?
Does the voltage swing equally as far (both positively and negatively) when you rotate the shaft of the pot the same amount in either direction from the center position?
Connect the potentiometer as shown to the two 15v voltage regulators. The output is on pin 3 of each regulator (confirm that you read plus/minus 15v on those pins before making the connections). Power up the amp and confirm that the voltage on the wiper terminal of the pot swings to ±15v. Set the shaft of the potentiometer to its center position. Connect the wiper of the pot to pin 3 of the driver board.
Connect the black probe of the multimeter to the ground terminal of the amplifier. Connect the red probe to the left + terminal when testing the left channel. Connect the red probe to the right - terminal when testing the right channel. SLOWLY rotate the shaft of the potentiometer about 45° from the center position while watching the DC voltage on the multimeter.
It would be better (safer) if the input capacitors (C9 and C10) from both channels were removed.
Does the DC voltage on the speaker terminal go positive when you rotate it one direction and negative when you rotate it the other direction?
Does the voltage swing equally as far (both positively and negatively) when you rotate the shaft of the pot the same amount in either direction from the center position?
Attachments
Ok Perry, here's the results...
With +15 vdc driving pin 3:
L+ out (orange lead) = +10.66 vdc
R- out (brown lead) = +8.68 vdc
With -15 vdc driving pin 3:
L+ out (orange lead) = +32.35 vdc
R- out (brown lead) = +32.35 vdc
Hmmmm... no negative vdc through the entire potentiometer sweep of either channel.
Power supply checks out good with -32.5 vdc.
Any thoughts?
Thanks Perry,
Chris
Just got the schematics from Rockford for the HD Modules...maybe they'll help?
Tried to upload pdf! The forum says it's too big! 494k...come on!!!!!
I'll try to PM you with the pdf. Maybe you can post it to this thread so others may benefit?
With +15 vdc driving pin 3:
L+ out (orange lead) = +10.66 vdc
R- out (brown lead) = +8.68 vdc
With -15 vdc driving pin 3:
L+ out (orange lead) = +32.35 vdc
R- out (brown lead) = +32.35 vdc
Hmmmm... no negative vdc through the entire potentiometer sweep of either channel.
Power supply checks out good with -32.5 vdc.
Any thoughts?
Thanks Perry,
Chris
Just got the schematics from Rockford for the HD Modules...maybe they'll help?
Tried to upload pdf! The forum says it's too big! 494k...come on!!!!!
I'll try to PM you with the pdf. Maybe you can post it to this thread so others may benefit?
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Is positive 15v reaching the driver board 15v supply pin?
Do the output transistors have full positive rail voltage on them?
Email me a copy of the driver board schematic, please.
babin_perry@yahoo.com
Do the output transistors have full positive rail voltage on them?
Email me a copy of the driver board schematic, please.
babin_perry@yahoo.com
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