Several parts-related questions

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1) What is the C3207 K204 transistor? And with what more US-friendly it can be subbed? It looks like > 1A high voltage one... Used in driver daughter-boards of JL amps.

2) Stupid one: what is the form factor and wattage of most commonly used small SMD resistors in RF, JL, and a lot of other amps? There different cases there, but I can't figure out correctly from third attempt what is the case for smallest ones :eek:

3) Why some amps (JL slash in particular) refuses to work with impulse AC/DC power supply :confused: It overloads outputs with a lot of 60Hz noise... Other amps are totally fine.

Thank you!!!
 
The information I found on the 3207 said it was 0.1 amps at 300v. The only place I could find that had it in stock (according to their site) is http://www.universal-semi.com/ .

The MPSW42 is a common part and should serve as a replacement but pins 2 and 3 must be reversed (ECB vs EBC). Of course, you should use the exact replacement but you may have this one in stock (especially if you work on a lot of MTX amps).

The smallest common chip resistor is an 0805 (0.08"x0.05"). You can measure them in the board with a dial caliper. The next larger size is 1206.

Is your signal source grounded to you power supply? If it's not grounded to the supply, that can cause problems. If the amp shuts down on the power supply, I've had it happen and I've talked to several other techs that have seen the same problem. In virtually all cases, the amps played fine when reinstalled in the vehicle.
 
Thanks a lot, Perry!
I'll try these transistors.
Last time I got 1206 resistors, one size miss :D
And yes, source is not grounded to power supply, with RCA's unplugged there is no noise. Reinstalled in car, amps works great. Worse case - JL class D monoblocks... total PITA to test properly
 
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