I thikn I found at least the LED issue. Q901 (which was a previous suspect) is not measuring up right. I also removed Q801 which is the same part. The transistor which came out of Q901 isnt diode checking between Legs 3-1 (3 Com). Q801 checks out just fine.
I have a few general purpose transistors which may fit the bill for Q901.
Q901 and Q801 are K016A1266Y transistors. The F303 service manual says both these parts are KTA-1266-Y transistors. Its a general purpose PNP transistor.
KTA1266 pdf, KTA1266 description, KTA1266 datasheets, KTA1266 view ::: ALLDATASHEET :::
It looks like I might be able to use a 2N3906 if I cross without shorting legs 2 and 3. I have a few others as well.
I have a few general purpose transistors which may fit the bill for Q901.
Q901 and Q801 are K016A1266Y transistors. The F303 service manual says both these parts are KTA-1266-Y transistors. Its a general purpose PNP transistor.
KTA1266 pdf, KTA1266 description, KTA1266 datasheets, KTA1266 view ::: ALLDATASHEET :::
It looks like I might be able to use a 2N3906 if I cross without shorting legs 2 and 3. I have a few others as well.
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Looks like putting a twisted 3906 in place of the KTA1266 may have solved the LED issue. The LED is shining brighter than before, plus the amp is staying powered up. I'm going to put the rects back in.
Put the rects back in, and I can now adjust the rail voltage up to 40v and the amp does not power off like it did before. LED is shining just fine now as well.
What do I set the rail voltage to for this amp? The MRV-F303 service manual says 53v across the rects, but I think this amp could be a little higher being a mono-block. This amp has 50v rail caps, B688 and D718 for outputs.
What do I set the rail voltage to for this amp? The MRV-F303 service manual says 53v across the rects, but I think this amp could be a little higher being a mono-block. This amp has 50v rail caps, B688 and D718 for outputs.
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In the end, the two power fets IRFZ48N on the right side (under the metal) needed refreshing. Also the small TO-92 transistor just to the right of the red/black connector for the LED A1266 was failed.
This amp seems very stable with the 2N3906 in place of the A1266, as well as the IRF3205s in the power supply.
I just need to find out what rail voltage to set this amp to and I'll probably order the correct TO92.
This amp seems very stable with the 2N3906 in place of the A1266, as well as the IRF3205s in the power supply.
I just need to find out what rail voltage to set this amp to and I'll probably order the correct TO92.
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The SM for the T303 also states that the rail-rail voltage should be set to 53v. Setting it to 70v (±35v) probably won't be a problem. The amp will make more power but will run hotter. If it's abused, it will be more likely to fail.
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