I have an audio amplifier (which doesn't work) and I'd like to get it working because it's good stuff (Fender Rumble 150 Bass Amplifier Head) 
It just doesn't turn on. From what I can see the power supply (ICEpower 50ASX2) doesn't have any active output... but it's something more complex than the ones I've been trying to repair and learn, this one has more components :
If anyone can give me some help, its possible to obtain the full schematic for this power supply? I found some information available but its only:
Amp Schematic
Power Supply Manual
Power Supply Datasheet
I've been doing some measurements and unfortunately the fuses (which are about 3) are all fine, the 2 giant capacitors (primary side) have a voltage of ~150V each
On the secondary side, I don't have any voltage, even on the Enable Pin that should be +5V (according to the manual) has 0V.
There is one component that is an NTC 5.0 and has a resistance of ~5R, which makes me believe that it's fine too.
All the elect. capacitors from the board, i measured them (with the multimeter in the capacitor mode) and the values, even being in the circuit (I didn't remove them), seems to be ok, and they seem to be of good brand and quality..
The IC SG3525 wont starts, it only has ~1.3v at Vcc pin, From what I see pin 15 is connected to a circuit that has a PNP Transistor (BCP53), and this PNP has Base and Emitter with ~15v input. But Collector Output is only ~1.3V:
http://youtu.be/VXpCVsWPq4M
Any idea?
It just doesn't turn on. From what I can see the power supply (ICEpower 50ASX2) doesn't have any active output... but it's something more complex than the ones I've been trying to repair and learn, this one has more components :
If anyone can give me some help, its possible to obtain the full schematic for this power supply? I found some information available but its only:
Amp Schematic
Power Supply Manual
Power Supply Datasheet
I've been doing some measurements and unfortunately the fuses (which are about 3) are all fine, the 2 giant capacitors (primary side) have a voltage of ~150V each
On the secondary side, I don't have any voltage, even on the Enable Pin that should be +5V (according to the manual) has 0V.
There is one component that is an NTC 5.0 and has a resistance of ~5R, which makes me believe that it's fine too.
All the elect. capacitors from the board, i measured them (with the multimeter in the capacitor mode) and the values, even being in the circuit (I didn't remove them), seems to be ok, and they seem to be of good brand and quality..
The IC SG3525 wont starts, it only has ~1.3v at Vcc pin, From what I see pin 15 is connected to a circuit that has a PNP Transistor (BCP53), and this PNP has Base and Emitter with ~15v input. But Collector Output is only ~1.3V:
http://youtu.be/VXpCVsWPq4M
Any idea?
Last edited:
Although I couldn't click on your links due to the fact I don't have Google/youtube looking elsewhere and I quote here---pin 13+15 are power pins.Vc should have between 5-35 volts and Vin should be between 8-35 volts.
So around 1.3 volts at Vc will stop the operation of the chip.
So around 1.3 volts at Vc will stop the operation of the chip.
Last edited:
No, that's a different ICE part. This is an ICE power supply with a Fender design TDA2050 power IC for the audio path.
Don't TDA2050s sometimes fail in stage-amp duty? How do we know if it is the audio amp or the power supply?
Attachments
In case it may be of any help to others. I have received for servicing one of those IcePower PCBs. Not to mention that there are no schematics available, so some investigations are required if you have the will to go ahead. I first did some visual inspections and no aparent damages were on sight. Then I began to read some voltages and found that though the DC voltage on the main capacitor was OK, the supply voltage on the 3525 was 0 volts. It is hard to follow tracks on such a compact thing so I did some random measures and component tests to discover that the capacitor marked within a red mark was shorthed. This is, to my knowledge, an anti-spike filter. I did not have its value so as a typical value I used a 10nF cap which, to this moment, has been working fine. It is clear that bypassing the diode, when sorted, there was some kind of protection acting.
Hope it helps.
Hope it helps.
I'm know that this is a old topic, but I encountered a similar issue with my 125ASX. I noticed that the VCC supply was only 1.3 volts. Upon further investigation, I discovered that the small capacitor in the VCC supply had a reduced capacity. After replacing the capacitor, my board back to life. In the case of the 50ASX, it appears that C330 might faulty.
Pay special attention to this issue. Today, it is the second unit I repair with, exactly, the same problem. From a different customer and installed on a different brand equipment. Maybe a defective quality control of the component or another problem regarding design. I am not going to go any further but I think it is interesting to let you all know.
Old topic I know, but I have a 50ASX2 that does not work. It did work. I want to use as a guitar speaker power amp, and my speaker is a 16 ohm. I read on a forum to use an audio transformer to reduce the ohms. I got a NTE4 1:4. Hooked it and it worked but not much change in volume so I switched it around in case I had the secondary and primary wrong. Again it worked but not much volume change. So I took the NTE4 completely out. Then the amp did not work. Any help would greatly appreciated.