You're gonna kill me...
Outputs were getting hot cause I didn't have them clamped down all the way. That's why it was good from a cold start.
Outputs were getting hot cause I didn't have them clamped down all the way. That's why it was good from a cold start.
I bet you won't make that mistake again. 🙂
Does it work properly now or does it still have problems?
Does it work properly now or does it still have problems?
Been playing a little Miles Davis for about 15 minutes into a bridged load.
What I don't understand, is why there was so much voltage present at the output jacks, but it's not blown outputs?
Was this strictly a DC offset problem because the omp amps weren't operating? Or was this amplification of DC offset of the op-amps?
What I don't understand, is why there was so much voltage present at the output jacks, but it's not blown outputs?
Was this strictly a DC offset problem because the omp amps weren't operating? Or was this amplification of DC offset of the op-amps?
The op-amps probably had excessive DC on their outputs. Although the power amplifier section is AC coupled to the preamp section (which should block the DC), there was probably some leakage through the coupling capacitors.
Before you reassemble the amp completely, solder the bell of the RCA jack shield to the frame of the RCA jack. They get loose and cause the amp to oscillate when they break contact (which can blow the outputs or the speakers).
http://www.bcae1.com/temp/P4260028.JPG
http://www.bcae1.com/temp/P4260028.JPG
I already did that per the tutorial.
Which transistors should I get to replace the A06/A56? And those cool heatsinks are called what?
Which transistors should I get to replace the A06/A56? And those cool heatsinks are called what?
I use a 2N6488 and a 2N6491. The Digi-Key part number is HS121 for the heatsinks.
If you do this...
Clean the pads with desoldering braid.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8940b.jpg
Bend the legs as shown and make sure that the legs don't contact any other traces or components.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8942b.jpg
Install the heatsinks (with heatsink compound).
http://www.bcae1.com/temp/mtxregmod8302/IMG_8945b.jpg
Use a piece of stiff cardboard, or fishpaper (preferred) to help support the regulators (to take the stress off of the pads). Make sure it goes to the board between the diodes.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8946b.jpg
Apply adhesive to the point where the top of the sink meets the fishpaper. Make sure you don't get any on the transistors.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8950b.jpg
The fishpaper needs to be just short of contacting the cover.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8954b.jpg
Glue a piece of closed cell foam to the cover so that it applies pressure to the fishpaper when the cover is replaced.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8955b.jpg
If you do this...
Clean the pads with desoldering braid.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8940b.jpg
Bend the legs as shown and make sure that the legs don't contact any other traces or components.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8942b.jpg
Install the heatsinks (with heatsink compound).
http://www.bcae1.com/temp/mtxregmod8302/IMG_8945b.jpg
Use a piece of stiff cardboard, or fishpaper (preferred) to help support the regulators (to take the stress off of the pads). Make sure it goes to the board between the diodes.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8946b.jpg
Apply adhesive to the point where the top of the sink meets the fishpaper. Make sure you don't get any on the transistors.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8950b.jpg
The fishpaper needs to be just short of contacting the cover.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8954b.jpg
Glue a piece of closed cell foam to the cover so that it applies pressure to the fishpaper when the cover is replaced.
http://www.bcae1.com/temp/mtxregmod8302/IMG_8955b.jpg
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