got a profile a400xl that needs attention.
have not found much info on it other than a "mosfet" 400 watt bridgeable amp.
i doubt very seriously that this amp will run more than 75 rms per channel into 4, but probably more like 2 ohms.
and it appears to me that the only "mosfet" portion is the fets in the power supply.......
love the marketing.
power supply fets are gone.
"source" resistors not identifiable.
(perry, i will trace the resistors out to see what they go to since i don't have and can't find schematics)
should i bother with this amp?
have not found much info on it other than a "mosfet" 400 watt bridgeable amp.
i doubt very seriously that this amp will run more than 75 rms per channel into 4, but probably more like 2 ohms.
and it appears to me that the only "mosfet" portion is the fets in the power supply.......
love the marketing.
power supply fets are gone.
"source" resistors not identifiable.
(perry, i will trace the resistors out to see what they go to since i don't have and can't find schematics)
should i bother with this amp?
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If no outputs have failed, it probably won't be too difficult to repair.
If you were referring to the gate (not source) resistors, they are likely 100 ohms. I'm assuming that the amp has Z44s in the supply.
If you were referring to the gate (not source) resistors, they are likely 100 ohms. I'm assuming that the amp has Z44s in the supply.
In the only photos I have of a Profile amp, they use 4.7 ohm resistors. Check the 0.22 ohm capacitor to confirm that it's not shorted.
These resistors are not damaged by shorted output transistors. They are typically damaged when the amplifier is driven into hard clipping for long periods of time. They can also be damaged if there is a fault in the amp or the signal line (open shields) that's causing the amp to oscillate at high frequencies.
These resistors are not damaged by shorted output transistors. They are typically damaged when the amplifier is driven into hard clipping for long periods of time. They can also be damaged if there is a fault in the amp or the signal line (open shields) that's causing the amp to oscillate at high frequencies.
Neither did I until a friend called and told me about it.
I'm going to learn to proofread one day... just after I learn to spell and type.
I'm going to learn to proofread one day... just after I learn to spell and type.
I had couple of those and bajas. I fix them because they are usually easy to do and appear to be a standard design. IIRC I let the last one go to the local pawnshop in a trade. I tested it, it worked....I'd guess you are right about the ratings but if you needed a 2x ~75 it should work ok, or for a spare or test unit. I've seen worse. They are not worth a lot, maybe I just learn from them lol.
Great number of class AB amps are mosfet PS and BJT outputs. I think they refer to old amps (80s?) that didn't have mosfets in the PS, and they are an upgrade for a PS. Some of the V12 alpines are mosfet outputs, old autotek, I'm sure Perry can list most of them. In the alpines they look pretty puny compared to the BJT they typically used, they can handle a lot of power for their size. I've been told they sound the same, 🙂, I'll be trying a mrv-t757 soon.
I'll look and see if I have another one like that. Have one but don't recall.
Great number of class AB amps are mosfet PS and BJT outputs. I think they refer to old amps (80s?) that didn't have mosfets in the PS, and they are an upgrade for a PS. Some of the V12 alpines are mosfet outputs, old autotek, I'm sure Perry can list most of them. In the alpines they look pretty puny compared to the BJT they typically used, they can handle a lot of power for their size. I've been told they sound the same, 🙂, I'll be trying a mrv-t757 soon.
I'll look and see if I have another one like that. Have one but don't recall.
I have an A400XL that my brother blew in his car. I need to replace the 2.7 ohm 5% resistors (red, violet, gold, gold) at R134 & R234. What wattage is the resistor and where can I get it? Here is a cellphone pic.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
They appear to be 1w resistors but size isn't always a good indicator of power handling. Buy the highest wattage resistor that will fit in the allotted space. Digikey or mouser will have a suitable replacement.
Thank you PB! Are saying I can use this resistor as a replacement?
Eagle 2.7 ohm - Red-Violet-Gold-Gold, Metal Oxide Film Resistor, 10 watt, 5%, Non-inductive"
An externally hosted image should be here but it was not working when we last tested it.
If you can get the leads in the board without doing any damage and it will fit (likely only standing), it will work but you don't need anything that large. Looking at the board photo, I'd suggest either a 1 or 2 watt (something similar in size to the original). From the photo, it appears that the body length (laying down) is limited to ~1/2 inch so that's likely a standard 1w or a miniature 2w.
The PPC2.7W-2CT-ND from digikey is a miniature 2w that should fit.
http://www.vishay.com/docs/28729/28729.pdf
The PPC2.7W-2CT-ND from digikey is a miniature 2w that should fit.
http://www.vishay.com/docs/28729/28729.pdf
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My fault guy! I clicked on PPC2.7W-2TR-ND instead of PPC2.7W-2CT-ND. The site will not let me change the Country from CANADA to USA under the Shipping Address.
I'm back! Amp turns on to a big thump and goes into protect. I think I need to replace the 0.22uF capacitors. Does R133 and R233 take the same resistors as R134 and R234?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
First, you should remove all of the brown fixative and check all components that it was applied over their body. R133, etc.
A loud pop would seem to indicate a shorted output.
A loud pop would seem to indicate a shorted output.