Link to schematic for reference.
I have an out of warranty Alpine PDX 1.1000. About 3 months ago, it quit working. Found the fuses blown, replaced, but they blew as soon as the system was turned on. Ordered the schematic and found two FET's had shorted. Replaced all four FET's in the array Q401, Q402, Q405, Q406. Attempted to bench test AMP, had no output. Started checking voltages at the FET's and found to be out of spec. Decided to swap PWM driver IC307 with IC308 and found a short in IC307, replaced IC307. Now I am back to immediately blowing the fuse when I turn on the AMP, and have found Q306 to be getting extremely hot.
I can't seem to locate a data sheet on Q306 (KTD718-O), but there is no obvious short. While Q306 may be bad, I am thinking that something else is shorting, causing it to cook. I have vary limited test equipment, and am debating on just replacing the amp as I have already spent over $100 with out success. Dose anyone have any suggestions on what else to check on the amp before I hit up ebay for a new one?
I have an out of warranty Alpine PDX 1.1000. About 3 months ago, it quit working. Found the fuses blown, replaced, but they blew as soon as the system was turned on. Ordered the schematic and found two FET's had shorted. Replaced all four FET's in the array Q401, Q402, Q405, Q406. Attempted to bench test AMP, had no output. Started checking voltages at the FET's and found to be out of spec. Decided to swap PWM driver IC307 with IC308 and found a short in IC307, replaced IC307. Now I am back to immediately blowing the fuse when I turn on the AMP, and have found Q306 to be getting extremely hot.
I can't seem to locate a data sheet on Q306 (KTD718-O), but there is no obvious short. While Q306 may be bad, I am thinking that something else is shorting, causing it to cook. I have vary limited test equipment, and am debating on just replacing the amp as I have already spent over $100 with out success. Dose anyone have any suggestions on what else to check on the amp before I hit up ebay for a new one?
http://www.keccorp.com/data/databook/pdf/KTD/Eng/KTD718.pdf
Do you have a large (25w+) 2 ohm current limiting resistor? An H6054 headlamp will also work in most cases.
Have you tried removing the rectifiers from the board to confirm that the problem is in the audio section of the amp?
Can you break the connection between the VDD terminal of IC307/308 and Q306?
Do you have a large (25w+) 2 ohm current limiting resistor? An H6054 headlamp will also work in most cases.
Have you tried removing the rectifiers from the board to confirm that the problem is in the audio section of the amp?
Can you break the connection between the VDD terminal of IC307/308 and Q306?
Thank you Perry Babin for your guidance.
I am working on getting a resistor for testing.
The Q306 rectifier tests good.
There isn't a trace that I can get to to break the VDD connection, but I could run Q306 externally without connecting the VDD. From what I can see, that would remove positive supply to the PWM drivers and isolate that portion of the circuit. I will post back with my findings.
I am working on getting a resistor for testing.
The Q306 rectifier tests good.
There isn't a trace that I can get to to break the VDD connection, but I could run Q306 externally without connecting the VDD. From what I can see, that would remove positive supply to the PWM drivers and isolate that portion of the circuit. I will post back with my findings.
Made a few new discoveries on that line. R404, R405 and R406 are open and C320 was cracked. Also discovered that the grounds are not connected on the PCB, but rely on the screws to complete the circuit to the chassis. I hadn't been installing them for my tests. 
Now ordering some caps and resistors, at least they aren't as expensive as the FET's and IC's.
I am going to hold off swapping the T401/2 chokes as they are sucking up all the heat making it difficult to desolder with my equipment.
Now ordering some caps and resistors, at least they aren't as expensive as the FET's and IC's.I am going to hold off swapping the T401/2 chokes as they are sucking up all the heat making it difficult to desolder with my equipment.
Thank's ozracing. I have been over the entire board with a magnifying glass and there is nothing obvious that I can find. The only reason that I found the broken cap is because I got no reading when testing it and when I went to desolder it, part stayed on the board. BTW, this is a SMT ceramic cap.
Hi to all.I didn't have experience to work on PDX-1.100 ,but I repaired three of PDX-1.600 What I see from your schematic.In those amps only differnce in amount of power suplly fets and also different drivers for them.PDX-600 uses only 8 fets in power suplly ,yours uses 12 of them.These amps are very good quality built and also they are easy to repair ,if follow step by step.This PDX amp based on the same schematic as MRP-M1000.They did only one thing in this newest models,changed power suplly fets which was IRF3205 to newest directFETs also from IRF.I repaired like 15 ALPINE MRP-M1000 amps.These amps are simpliest I ever had.
If you 100% sure your power suplly section is working fine.You should go only to output stage .Make sure ,you have neccesary voltage to suplly drivers (IR2010S) To measure voltage on KTD718 ,you have to put negative probe on negative rail which is -Vss and positive to emmiter of KTD718.This regulator is referenced to -Vss not to the ground.In my experience when some mosfets in output stage failed.It will get one shorted MURS120 ( replacable with ES2D) If MURS shorted ,100% IR2010S is dead too.And most important thing ,you will find three paralleled resistors of 6,8 Ohm will open too.If you replaced all those parts(IR2010S,MURS120,Three resistors 6,8 Ohm) and also shorted output fets(IRFB4227) on the beginig of your work on this amp.It will work again as new one.But I'm sure you did a mess inside,and now it isn't easey to find the problem.Sorry
If you 100% sure your power suplly section is working fine.You should go only to output stage .Make sure ,you have neccesary voltage to suplly drivers (IR2010S) To measure voltage on KTD718 ,you have to put negative probe on negative rail which is -Vss and positive to emmiter of KTD718.This regulator is referenced to -Vss not to the ground.In my experience when some mosfets in output stage failed.It will get one shorted MURS120 ( replacable with ES2D) If MURS shorted ,100% IR2010S is dead too.And most important thing ,you will find three paralleled resistors of 6,8 Ohm will open too.If you replaced all those parts(IR2010S,MURS120,Three resistors 6,8 Ohm) and also shorted output fets(IRFB4227) on the beginig of your work on this amp.It will work again as new one.But I'm sure you did a mess inside,and now it isn't easey to find the problem.Sorry
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.