Volume reduction with same input ( 4 years old),
I purchased a used Mackie SWA1501 ( 4 years old, purchased 4/09). It tested fine before I purchased and have used several times with no problems. Recently something has happened, volume on the 1501 is much less with the same input level (gain knob on 1501 at 12:00). I must turn up to near full gain on the 1501 to get the same volume I had previously. I have checked input cords, etc. There is not noticeable speaker distortion or hum. I understand this amp has multiple internal fuses- could I have blown one and only be amplifying on half of the amp? I have green on power LED, the signal LED will flicker with input, LED for overload is not lit.
If it is a fuse- can I replace it my self? I am moderately skilled at simple electronic repair.
If it is a fuse- can I replace it my self? I am moderately skilled at simple electronic repair.
Audio Players & Recorders - Mackie - SWA1501 Subwoofer
Answers & Comments
Macie SWA1501 volume reduction problem posted on July 31,2009- Tried to follow your advice on pulling out the amp and finding the 5V and 12V regulator IC. I pulled out the amp and looke for over an hour and found no component with the number 7805 or 7812 on it. I took it to work, and have our electronic tech look it over with his high power lighted magnifying lens and he couldn't find them. I looked extensively for burned parts- none, bad solder connections- none, and any other sign of damage. The only thing I could find is light whitish corrosion on some of the solder connections- these I cleaded with fiber brush and contact cleaner? Any suggestions would be appreciated. R Marlow
What are you using to feed the sub? Are you sure that the signal level you are presenting to the sub is the same?
Dan
Thanks for the update. The next step is to check the input control on the sub itself and the power supply. If you have lost the 5V supply, you will not get the initial pre-amp section boost and hte overall volume will be low. Check the board for poor solder connections at the 5V and 12V regulator ICs. These will be 3-legged parts that look like transistors that should be marked 7805 and 7812. If you have a meter and can turn on the unit while open safely, check the voltages to ground on each pin. You should see for the 7805 something like this: (>5V, 0V, and 5V) The >5 reading will likey be 12V or so. For the 7812 the readings will be similar, but greater than 12V and 12V rather than 5.
Please check that and update this again.
Thanks,
Dan