mtx blown please help

[amplifiers inc]

When servicing the 2300 its very important to replace the complete bank of IRF540's with a Vgs matched set of 4. If Fets have failed in both the pos and negative half a VGS matched set of 8 will be required. When I designed this unit I used very small source degeneration resistors, mainly just for current sensing purposes, so there is almost no source degeneration and at the power dissipation levels involved if each set of 4 fets isnt VGS matched to within 20 mA of of each other under high load the (the lowest VGS threshold fet will grab all the current and blow) unbalance will cause premature failure.

[sdoom]

Hi amplifiers inc,


could you tell me the specs for the RTA450 and the RTA2150 ?

I fixed both amps (actually there had only been bad soldier joints and a few old capacitors) . As I have seen a couple of different amplifiers in my life I was impressed that with so many high power parts the power ratings are rather low. Are those amps 1ohm stable ?

Thx

Stephan

[amplifiers inc]

Well first of all there were at least 2 different series of road thunder amplifiers in the 90's. The first series was pre 1994 and they were pretty weak design wise as they were made for MTX by another manufacturer and were essentially just a me too amplifier offering. The second series debuted circa 1998 and were a lot better because they were derived from the original Thunder series of mobile amplifiers designed 94-97. The original Thunder series were packed full of innovations and original engineering tailored to optimize each area of the design from power converter to output stage and the 98 Road Thunder series were more or less clones of these with a reduced feature set such as lower quality power and speaker connectors, lower mass heatsinks, less costly logos etc.