I received an SM-900 in for repair and noticed R1/R2 & R3/R4 are in series on the schematic. However, on the PCB they leads of one are soldered to the other and are in parallel.
Is this a design flaw? I have attached the schematic and any information would be really helpful. Thank you.
Is this a design flaw? I have attached the schematic and any information would be really helpful. Thank you.
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In the old days you could have called SWR directly but since Fender bought them you can't get squat out of them. Try getting in touch with them anyway. Maybe someone with lots of SWR experience will chime in, I've repaired a few but never noticed that.
Craig
Craig
There is a very high current passing if the resistors are the value stated and in parallel! The Zeners are only 1Watt, so does the rest of the circuit draw all that current? 60Volts at 550R is nearly 120mA!
Check their cold value.
Check their cold value.
I'd leave them as you found them, unless they are causing trouble. That schematic is legit, but they also showed other schematics with different values.
For instance:
Read the notes in the SM400 drawing, it calls out what you have for SM900, but look at the later SM500 set, which includes the 4004. the 4004 has similar rails to yours and has the resistance of just one resistor rather than either combination of two.
SO really, I wouldn't stress over it much.
For instance:
Read the notes in the SM400 drawing, it calls out what you have for SM900, but look at the later SM500 set, which includes the 4004. the 4004 has similar rails to yours and has the resistance of just one resistor rather than either combination of two.
SO really, I wouldn't stress over it much.
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