So I finally got the cajones up to try to fix this smoked mtx 1501d I got scammed on.
Replaced all the 75339 fets (all shorted out) and a couple melted poly caps right near them.
There's also a cracked (looks like physical damage) diode I replaced that leads to the fet in the center of the board.
I think the previous abuser of this amp "modded" it, since Q240 is missing.
So on first power up (no speakers, no inputs) I get the power led and about 3 seconds later LED238 near the input section lights up.
LED399 in the center of the large caps never lights.
Trying my test again with a speaker connected and an audio source. Soon as LED238 lights I get a very faint buzzing on the speaker. (About .1 volts on the dmm).
No idea where to go now. 🙄
Replaced all the 75339 fets (all shorted out) and a couple melted poly caps right near them.
There's also a cracked (looks like physical damage) diode I replaced that leads to the fet in the center of the board.
I think the previous abuser of this amp "modded" it, since Q240 is missing.
So on first power up (no speakers, no inputs) I get the power led and about 3 seconds later LED238 near the input section lights up.
LED399 in the center of the large caps never lights.
Trying my test again with a speaker connected and an audio source. Soon as LED238 lights I get a very faint buzzing on the speaker. (About .1 volts on the dmm).
No idea where to go now. 🙄
Have you check the gate resistors ? I noticed most of the time when the mosfets transistors blown the gate resistors go to. Take your DMM and check all the resistors that are in front of the mosfets.
http://www.samengstrom.com/nxl/10116/5_band_resistor_color_code_page.en.html
http://www.samengstrom.com/nxl/10116/5_band_resistor_color_code_page.en.html
doh!
I should of thought of that. (I had to replace one on that 6100d I was messing with)
There two of them, and they're both open.
I'll have to see if I can clean them up. They're a little dirty from the magic smoke, as if they weren't hard enough to read to begin with. 🙂
I should of thought of that. (I had to replace one on that 6100d I was messing with)
There two of them, and they're both open.
I'll have to see if I can clean them up. They're a little dirty from the magic smoke, as if they weren't hard enough to read to begin with. 🙂
I have that problem all the time man, if I cant see the colors on the resistors I just take the resistor number thats printed on the PCB and phone in to the manufacture and they will look it up in their service manuals.
Does "39R2" sound about right? I got one clean as I could and can still barely ready it with a magnifying glass. 🙂
Is there a size to these little smd resistors? Last time I ordered SMD diode's, they were too small to even cover both solder pads.
Is there a size to these little smd resistors? Last time I ordered SMD diode's, they were too small to even cover both solder pads.
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