Hi. I am currently repairing 2x Mackie SRM450 V3 for a friend. Both speakers have the bass driver amplifier sections blown.
I discovered that on the TDA8954 amplifier chips that one of the output legs was shorted to the corresponding bootstrap leg.
I find it strange how there is a lack of people talking about these or this repair. He used them at a wedding in a bar and i was also there. We borrowed a sub so i guess he never noticed when the bass from the Mackies stopped working. He took them to another event not knowing and had to cancel on site when he found out.
I am not a huge fan of these tda chips. 420W bridged in such a small chip with such a small heat-sink. Perhaps these need a PCF circuit to make the most of them but if both can blow during a fairly normal night that's not too reliable.
Anyway. I have ordered the parts and will ty to post here if the repair is that simple.
Notes:
Mackie seem to be gluing the speaker cable and led connector to the amp module making it quite difficult to separate. I 1/2 removed the silver cover and worked as much as i could around the gap in the connector with a knife and a flat blade screwdriver taking care not to destroy anything. Eventually i manged to separate them.
Take care when removing the TDA chips as i did lift one track slightly. I will try hot air station on the 2nd one. On the 1st one i removed i took some solid copper wire the length of the chip and i flooded it and the legs with solder taking care not to remove the smd cap closest. I could then lift one side and then work on the adjacent side.
There is no under-chip central pad, just the legs.
It was the exact same short on both TDA modules. I think it was pin 21 and 22 shorted together where the opposite pins (15 and 16) were not shorted.
Other things i noticed were that many of the nuts and bolts were not too tight including those that hold the drivers in place. One of the silver covers was more difficult to remove as some adhesive had stuck it down in places, you have to get a blade under there. Also when removing the main board from it's heat-sink you may find you need to cut some adhesive away from the heat-sink plate to separate everything.
Also, here is a V1 aside a V3. Many people still prefer the V1 as Mackie was originally made or owned by RCF The weight difference is huge!
I discovered that on the TDA8954 amplifier chips that one of the output legs was shorted to the corresponding bootstrap leg.
I find it strange how there is a lack of people talking about these or this repair. He used them at a wedding in a bar and i was also there. We borrowed a sub so i guess he never noticed when the bass from the Mackies stopped working. He took them to another event not knowing and had to cancel on site when he found out.
I am not a huge fan of these tda chips. 420W bridged in such a small chip with such a small heat-sink. Perhaps these need a PCF circuit to make the most of them but if both can blow during a fairly normal night that's not too reliable.
Anyway. I have ordered the parts and will ty to post here if the repair is that simple.
Notes:
Mackie seem to be gluing the speaker cable and led connector to the amp module making it quite difficult to separate. I 1/2 removed the silver cover and worked as much as i could around the gap in the connector with a knife and a flat blade screwdriver taking care not to destroy anything. Eventually i manged to separate them.
Take care when removing the TDA chips as i did lift one track slightly. I will try hot air station on the 2nd one. On the 1st one i removed i took some solid copper wire the length of the chip and i flooded it and the legs with solder taking care not to remove the smd cap closest. I could then lift one side and then work on the adjacent side.
There is no under-chip central pad, just the legs.
It was the exact same short on both TDA modules. I think it was pin 21 and 22 shorted together where the opposite pins (15 and 16) were not shorted.
Other things i noticed were that many of the nuts and bolts were not too tight including those that hold the drivers in place. One of the silver covers was more difficult to remove as some adhesive had stuck it down in places, you have to get a blade under there. Also when removing the main board from it's heat-sink you may find you need to cut some adhesive away from the heat-sink plate to separate everything.
Also, here is a V1 aside a V3. Many people still prefer the V1 as Mackie was originally made or owned by RCF The weight difference is huge!
