I have a repair problem with a Phoenix Gold Route 66. Both left channels of the front and sub amplifier (M44) are not working, but amplfier doesn't go into protection.
- Power supply is OK +/- 35V; +/- 28V; +/- 15V.
- Left sub channel only negative part of sinewave is visible on a scoop. Bias OK ???(...not sure..)
- all transistors seems te be OK, removed them, tested etc.
- output of the gain stages (opamps) are OK
- resistors OK
- diodes..??
So..i'm think I'm close but can't find a false part.....
Anyone..??
Rob.
- Power supply is OK +/- 35V; +/- 28V; +/- 15V.
- Left sub channel only negative part of sinewave is visible on a scoop. Bias OK ???(...not sure..)
- all transistors seems te be OK, removed them, tested etc.
- output of the gain stages (opamps) are OK
- resistors OK
- diodes..??
So..i'm think I'm close but can't find a false part.....
Anyone..??
Rob.
Hello,
Maybe i can be of help
PG uses a triple Darlington design for this amp like they do in the M, MS, & MPS series amps. I have found that the first set of to-126 transistors act like a form of protection for the amp channels by blowing open when placed in a over current state by to load.
So look at the 2SA1360 and its compliment across from it located in the very front areas of each channel. There are two sets of these the second set is closer to the pre-output drivers closer to the sink located to the back of the amp. these also can blow, but I have not seen this as much in my past on these amps.
If you are familiar with the M,MS,MPS series amps they have those little red LEDS in each channel. This amp does not use them but if it did they would be a indicator that that these TO-126 transistors have failed. I just repaired a MS-275 for a fellow forum member with this same issue. The LED was also blown open indicating a over current related failure.
Also ohm out every ceramic looking resistor. these are fuse type resistors ( green or grey bodied in color )and they will go open or very high ohms with any visual indication of being bad. These are the same fuse type resistors used in home and pro amplifiers as fire protection, so you should strive to replace them with the exact type units only.
Regular metal films and carbons will work, but DONT offer the protection that this type of fuse does from smoke and fire issues.
PG builds some very well engineered amps, I hope I have given you some insight on their wonderful design concepts.
I run all PG in my systems. If you have time please come visit us at
http://phoenixphorum.com/index.php
I hope this has been helpful and the insight I shared will give you new avenues of thought about you failed amp, and help you get her running like new
Maybe i can be of help
PG uses a triple Darlington design for this amp like they do in the M, MS, & MPS series amps. I have found that the first set of to-126 transistors act like a form of protection for the amp channels by blowing open when placed in a over current state by to load.
So look at the 2SA1360 and its compliment across from it located in the very front areas of each channel. There are two sets of these the second set is closer to the pre-output drivers closer to the sink located to the back of the amp. these also can blow, but I have not seen this as much in my past on these amps.
If you are familiar with the M,MS,MPS series amps they have those little red LEDS in each channel. This amp does not use them but if it did they would be a indicator that that these TO-126 transistors have failed. I just repaired a MS-275 for a fellow forum member with this same issue. The LED was also blown open indicating a over current related failure.
Also ohm out every ceramic looking resistor. these are fuse type resistors ( green or grey bodied in color )and they will go open or very high ohms with any visual indication of being bad. These are the same fuse type resistors used in home and pro amplifiers as fire protection, so you should strive to replace them with the exact type units only.
Regular metal films and carbons will work, but DONT offer the protection that this type of fuse does from smoke and fire issues.
PG builds some very well engineered amps, I hope I have given you some insight on their wonderful design concepts.
I run all PG in my systems. If you have time please come visit us at
http://phoenixphorum.com/index.php
I hope this has been helpful and the insight I shared will give you new avenues of thought about you failed amp, and help you get her running like new
Thanks for the tips. This amp doesn't use LED's, there are a lot diodes in series. I measured those "fuse" resistors allready (A ZX Ti500.4 had this problem), but they all seem to be OK.
The drivers are 2SA1360 / 2SD3423 and are normal transistors hfe ~200 AFAIK
I like the PG's, but they are a little tricky reparing them...
Rob
The drivers are 2SA1360 / 2SD3423 and are normal transistors hfe ~200 AFAIK
I like the PG's, but they are a little tricky reparing them...
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An externally hosted image should be here but it was not working when we last tested it.
Rob
DC offset is about 100mV and i checked all the resistors. Very strange behaviour..
I removed the whole powerstage, but still the distorted signal is there at the pre-stage.
I think the diodes are fault, maybe one is a zener. I just measure between left (faulty) en right channel to compare the voltages.
Rob.
I removed the whole powerstage, but still the distorted signal is there at the pre-stage.
I think the diodes are fault, maybe one is a zener. I just measure between left (faulty) en right channel to compare the voltages.
Rob.
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