Infinity PS-12
amplifier board — fixed.
The Infinity PS-12 has one of the best-documented failure histories of any subwoofer we've researched: a combined amplifier/power-supply plate built with cheap electrolytic capacitors and no cooling fan, which fails in the same handful of predictable ways again and again. If yours won't turn on, keeps blowing fuses, or has started buzzing or crackling, this is almost certainly repairable.
Is it really the board?
These are the failure patterns we see on the Infinity PS-12. Match your symptom before spending a cent.
- No power / won't turn on — standby LED stays red or flickersBOARD — WE FIX THIS
Either the main fuse has blown, or the standby timer capacitor and a negative-rail filter capacitor have degraded enough that the control circuit can't detect a valid ready state and stays locked in protection mode.
- Fuse blows repeatedly, including seconds after replacementBOARD — WE FIX THIS
A degraded filter capacitor lets the negative supply rail sag from its proper voltage, which removes the correct shut-off bias from the output MOSFETs' gates — they stay partially on, overheat, and short, blowing the fuse again almost as soon as you replace it. The output MOSFETs need replacing as a matched pair, not individually.
- Visibly bulging, leaking, or burnt capacitors on the amp plateBOARD — WE FIX THIS
The original design used several budget capacitor brands throughout the board, combined with a passive-only cooling design that runs hotter than it should — a combination that reliably cooks these capacitors well within the unit's service life. This is the root cause behind most of the other faults on this list.
- Clipping or distorted sound at moderate-to-high volume, worse after 30-60 minutes of playBOARD — WE FIX THIS
A pair of small shunt-regulator transistors were built with undersized power packages for this application; they overheat during extended high-volume use and their regulation accuracy drops, which shows up as clipping right when you'd expect the amp to be working hardest.
- Chirping or squealing noise right at power-upBOARD — WE FIX THIS
A single timing capacitor in the startup sequencing circuit degrades and causes brief oscillation as the amp powers up — a well-known, cosmetic-sounding fault that's a straightforward capacitor swap.
Why the original board fails
The PS-12's amplifier and power supply share one plate, cooled only by a small passive heatsink squeezed into the cabinet with no fan — and, in some installations, a mounting bracket that restricts airflow even further. That thermal environment is hard enough on its own, but Infinity paired it with electrolytic capacitors from several budget brands throughout the design. The combination is why PS-12 failures cluster so tightly around capacitor aging: bulging and leaking caps are usually where every repair investigation ends up, whether the symptom that got you there was total silence, a repeatedly blown fuse, clipping at high volume, or a chirp on power-up.
The one failure that goes beyond a simple capacitor swap is a repeatedly blown fuse traced to the output MOSFETs — once the negative rail sags far enough for long enough, those parts can short and need replacing as a matched pair using correctly specified parts, not whatever's on hand. Every fault on this list is well-documented and repeatable across many independent units, which is exactly the kind of failure pattern that makes a subwoofer a strong repair candidate rather than a coin flip.
Mail-in repair for this model
No standardized board yet — but our bench repairs these at component level, tested and shipped back.
- 01 Submit the repair form with your symptoms and photos
- 02 We confirm it's repairable and send our address — you ship just the board
- 03 Bench diagnosis, firm quote by email — no fix, no fee
- 04 Repaired, tested, shipped back — return shipping on us
Questions owners ask
My fuse keeps blowing every time I replace it. Is this hopeless?
No — this is one of the most predictable PS-12 faults we see. A sagging negative supply rail lets the output MOSFETs stay partially on and overheat; once we replace the correct matched pair and the capacitor causing the rail sag, the fuse holds.
The sound distorts after 30-60 minutes but is fine when it's cold. What's going on?
That's a textbook PS-12 symptom — a pair of small regulator transistors were built with less thermal headroom than this design really needed, so they drift out of spec once they've heated up during use. It's a known, repairable fault, not a sign the amp is dying overall.
How confident are you diagnosing this model specifically?
Very. The PS-12 has one of the most thoroughly documented failure histories of any subwoofer amplifier we cover — the same handful of faults show up consistently across many independent repairs, which lets us diagnose quickly and quote accurately.