Simmons Drum monitor schematic included

[nosaj]

i have this Simmons drum monitor had no output with DC on the speaker leads. Replaced the 4558 controlling the headphone out got sound up to there replaced the tda 7294. Get clean signal up to pin3. However output is very low and scratchy and broken up. i have tried a known good speaker and its still the same.
Could use some help and an what is a bootstrap?

Thank,s
nosaj

[g1]

no schematic showing

[nosaj]

Simmons DA50 RevF 28feb2008 gm.pdf

nosaj

[x-pro]

Check the electrolytic capacitors around the 7294

[nosaj]

Changed c31,c34, c39, c40. No change still sounds the same fizzy low volume. Headphone jack sounds great, Pin3 of the tda7294 sounds great too. Note this is the second 7294 install with the same sound.

nosaj

[x-pro]

what is the voltage at pin 9 and 10 of the 7294 chip?

[nosaj]

Using which ground? GND, chassis ground or M-S GND on pin1?

Thanks,
nosaj

[nosaj]

Chassis ground point pin9 4.6vDC Pin10 6.8vDC.
nosaj

[nosaj]

Pin13 +38.14vDC
Pin15 -38.15vDC
nosaj

[x-pro]

Which pins do you connect the speaker to - P1, P2 or P3, P4 ?

[nosaj]

The woofer goes on P3-P4
The tweeter goes on P1-P2
nosaj

[x-pro]

Are R50, C38 in good working order?
or 7294 marriage

[g1]

Where did you get the IC's from? Did you discharge all those related caps before install?

[nosaj]

Are R50, C38 in good working order?
or 7294 marriage

r50 measures 4.9 ohm C38 just swapped in a new cap. Still sounds the same.
nosaj

[nosaj]

Where did you get the IC's from? Did you discharge all those related caps before install?

Mouser and Audiolabs of GA. Yep just followed same procedures as the marshall mode 4. I've got one more on hand but its horizontal mount instead of vertical but i should be able to bend the leads some.
nosaj