Hi all,
I have an Infinity SSW-10 sub-woofer that stopped working that I acquired from family. Upon opening the woofer the fuse and 2 resistors (R1 & R2: 430 Ohm 1W 5%) were blown. I replaced both the fuse and the 2 resistors (437 Ohm 1W 1%). The PCB was also badly burned where the resistors were which damaged some traces, so I repaired them as much as I could with jumpers (see Trace Repair). I have attached both the repair manual as well as before/after pictures of my repair. See page 38 of the manual for the schematic and pages 34 & 35 for the PCB layout. Please note the capacitors (C30, C35, and C33) on the schematic should be swapped with (C31, C36, and C34) respectively.
Trace Repair: Both the pads for R1 & R2 were destroyed. I was able to scrape the solder mask on the 31V side to access the copper trace. On the 16V side jumper wires were used to connect to C7 and C8. On the solder side of PCB-1 there is a trace that runs under R1 & R2 from C10 to J4 then J4 to R10 on the component side. I used a jumper to go from C10 to J4. I also needed a jumper from R2/C7 to J7 pin 3 (the ribbon cable).
Test Voltages:
The +31V, -31V, and +16V rails look ok, but the -16V rail is not, and the relay is closing normally (although immediately and not delayed 1-5 seconds like the manual states). Looking at the repair manual (page 19) it mentions that a short on IC1 or IC2 could cause R1 and R2 to fail. It mentions to remove the ICs and test the voltages. Removing IC1 and IC2 only, does not produce a change in voltage across R3. According to the manual this implies a bad Zener diode ZD2. I replaced both ZD1 and ZD2 with new diodes, an still no change in voltage. By removing all 3 ICs (IC1, IC2, and IC3), the -16V rail returns to normal. This would imply that one or all of the ICs are bad, so I replaced them all (2x LF347N and 1x LF353N). However, with the new ICs in, the -16V rail returns to -.6V. I next turned to the filter capacitors C7 and C8 (47uF 50V). Since C8 has the bad voltage, I replaced C8 and still no change.
I am stuck, and any help would be appreciated. Where do I look next?
tl;dr: No load on PSU = Voltage Good. Load on PSU = Voltage Bad. Replaced ZD1, ZD2, IC1, IC2, IC3, C8
I have an Infinity SSW-10 sub-woofer that stopped working that I acquired from family. Upon opening the woofer the fuse and 2 resistors (R1 & R2: 430 Ohm 1W 5%) were blown. I replaced both the fuse and the 2 resistors (437 Ohm 1W 1%). The PCB was also badly burned where the resistors were which damaged some traces, so I repaired them as much as I could with jumpers (see Trace Repair). I have attached both the repair manual as well as before/after pictures of my repair. See page 38 of the manual for the schematic and pages 34 & 35 for the PCB layout. Please note the capacitors (C30, C35, and C33) on the schematic should be swapped with (C31, C36, and C34) respectively.
Trace Repair: Both the pads for R1 & R2 were destroyed. I was able to scrape the solder mask on the 31V side to access the copper trace. On the 16V side jumper wires were used to connect to C7 and C8. On the solder side of PCB-1 there is a trace that runs under R1 & R2 from C10 to J4 then J4 to R10 on the component side. I used a jumper to go from C10 to J4. I also needed a jumper from R2/C7 to J7 pin 3 (the ribbon cable).
Test Voltages:
Code:
V_c6 = +29V V_c5 = -29V V_c7 = +16V V_c8 = -.6V V_r2 = 12V V_r3 = 28V
I am stuck, and any help would be appreciated. Where do I look next?
tl;dr: No load on PSU = Voltage Good. Load on PSU = Voltage Bad. Replaced ZD1, ZD2, IC1, IC2, IC3, C8
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