Planet Audio Class D TT2250

confused256 · 25th January 2011, 10:16 PM

I think this is similar to problems ppia600 was having with similar amp in another post.
I have two planet audio TT2250d amplifiers having similar problems. On the output I get a triangle wave from 1-1.5v P-P. Fan not turning so checked driver Board and MPSA42 gets hot and I replaced with MPSW42, didn't change so I replaced all 4, still no change. With all 4 MPSW42 removed the MPSA56 get hot now, wave is gone on output. New MPSW42 into amp get hot and wave is back.
Power and output Fets good, removed inductors to check for shorts, wasn't sure if it shorted but I wedged wire over so it wouldn't in future, no change. One of the amps had one output cap blown off the board, replaced all 4, and checked inductors.
Rail voltage is +/-69.5
+/- 15 volts is ok
On the driver board is an IC that has number sanded off not sure if that is bad or what values should be.
Power IC values appear good.
All test with RCA unhooked and tried shorting rca to get a flat input and still there.
Any help would be much appreciated.

Perry Babin · 25th January 2011, 10:18 PM

Post the circuit board designations (Q124, Q125...) for the transistors you replaced with MPSW42s.

confused256 · 25th January 2011, 10:26 PM

Q125
Q124
Q121
Q120
Replaced MPSA42 with MPSW42s

Perry Babin · 25th January 2011, 10:33 PM

Do you have a scope?

Counting from the end of the driver board with the op-amp, does the voltage on pin 6 (on the connector to the main board) transition from rail voltage to approximately 0v within 15 seconds of applying remote voltage?

confused256 · 25th January 2011, 10:44 PM

SW pin it goes from 13volts to 0volts couple seconds after turnon.
Yes I have a scope.

Perry Babin · 25th January 2011, 10:50 PM

13v? It should have been nearer 70v. Place the black meter probe on the negative speaker terminal when measuring the voltage.

Also make sure that the amp is set to master. It will produce no audio in slave mode.

confused256 · 26th January 2011, 06:58 PM

70+ volts then back to 0
slave or master makes no difference

Perry Babin · 26th January 2011, 07:08 PM

Leave it set to master.

Do you have signal on pin 1 (nearest the RCA end of the amp) of the driver board?

confused256 · 11th February 2011, 08:01 PM

On pin 1 there is 0 volts.
Went back through driver board with soldering iron making sure traces/parts were soldered. Now triangle wave is gone on output but now on the speaker out I am getting almost square wave of 168Vp-p 112kHz(like the drv is being amplified), swapped driver board and same thing, now I might have two bad driver boards or something else in amp. Were else can I look or replace items.

Sorry about the down time from last post, Midwest blizzard of 2011 had me busy. I really appreciate the help.

Perry Babin · 11th February 2011, 08:04 PM

It sounds like that there is a bad connection on the output filter caps. I'm assuming that the caps are not overheating.

25th January 2011, 10:16 PM	#1
confused256 diyAudio Member Join Date: May 2005 Location: Missouri	Planet Audio Class D TT2250 I think this is similar to problems ppia600 was having with similar amp in another post. I have two planet audio TT2250d amplifiers having similar problems. On the output I get a triangle wave from 1-1.5v P-P. Fan not turning so checked driver Board and MPSA42 gets hot and I replaced with MPSW42, didn't change so I replaced all 4, still no change. With all 4 MPSW42 removed the MPSA56 get hot now, wave is gone on output. New MPSW42 into amp get hot and wave is back. Power and output Fets good, removed inductors to check for shorts, wasn't sure if it shorted but I wedged wire over so it wouldn't in future, no change. One of the amps had one output cap blown off the board, replaced all 4, and checked inductors. Rail voltage is +/-69.5 +/- 15 volts is ok On the driver board is an IC that has number sanded off not sure if that is bad or what values should be. Power IC values appear good. All test with RCA unhooked and tried shorting rca to get a flat input and still there. Any help would be much appreciated.

25th January 2011, 10:18 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Post the circuit board designations (Q124, Q125...) for the transistors you replaced with MPSW42s. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th January 2011, 10:33 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have a scope? Counting from the end of the driver board with the op-amp, does the voltage on pin 6 (on the connector to the main board) transition from rail voltage to approximately 0v within 15 seconds of applying remote voltage? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th January 2011, 10:50 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	13v? It should have been nearer 70v. Place the black meter probe on the negative speaker terminal when measuring the voltage. Also make sure that the amp is set to master. It will produce no audio in slave mode. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

26th January 2011, 07:08 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Leave it set to master. Do you have signal on pin 1 (nearest the RCA end of the amp) of the driver board? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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25th January 2011, 10:26 PM	#3
confused256 diyAudio Member Join Date: May 2005 Location: Missouri	Q125 Q124 Q121 Q120 Replaced MPSA42 with MPSW42s

25th January 2011, 10:44 PM	#5
confused256 diyAudio Member Join Date: May 2005 Location: Missouri	SW pin it goes from 13volts to 0volts couple seconds after turnon. Yes I have a scope.

26th January 2011, 06:58 PM	#7
confused256 diyAudio Member Join Date: May 2005 Location: Missouri	70+ volts then back to 0 slave or master makes no difference

11th February 2011, 08:01 PM	#9
confused256 diyAudio Member Join Date: May 2005 Location: Missouri	On pin 1 there is 0 volts. Went back through driver board with soldering iron making sure traces/parts were soldered. Now triangle wave is gone on output but now on the speaker out I am getting almost square wave of 168Vp-p 112kHz(like the drv is being amplified), swapped driver board and same thing, now I might have two bad driver boards or something else in amp. Were else can I look or replace items. Sorry about the down time from last post, Midwest blizzard of 2011 had me busy. I really appreciate the help.

11th February 2011, 08:04 PM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It sounds like that there is a bad connection on the output filter caps. I'm assuming that the caps are not overheating. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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