Amplifier or receiver produces no sound
Your amplifier or AV receiver powers up, the display lights up, but the speakers stay completely silent — and the cause is almost always hardware, not a setting. Behind this simple symptom you usually find a tripped DC-protection circuit, oxidised speaker relay, blown output pair or a preamp section that has gone dead.
AV receivers add another failure mode: HDMI handshake, the DSP processor and Dolby/DTS decoders — any of which can block the audio stream even when the speakers and cables are fine. Before bringing the unit in, it is worth running a short check on inputs, mute and the headphone jack.
No sound is one of the most common faults on Hi-Fi and home-theatre gear. Behind a single description hide very different problems: from an oxidised output-stage relay to fully blown output transistors placing DC on the speaker terminals. In a classic integrated amplifier or stereo receiver the audio signal passes through the input selector, preamp section, tone controls, volume potentiometer and power output stage before it reaches the speaker binding posts. At every one of these stages there are components whose failure causes silence: coupling electrolytic capacitors, differential-pair transistors, op-amp ICs (NE5532, OPA2134, LM4562), protection relays by Omron, Takamisawa or Fujitsu, and the output pairs themselves (2SC5200/2SA1943, MJL3281/MJL1302, or MOSFET IRFP240/IRFP9240). In AV receivers you add a DSP processor, HDMI switching and Dolby/DTS decoders, any of which can block audio in software. We run full bench diagnostics, scope the signal at every stage of the chain and agree a firm estimate before any work starts. If you decide not to proceed, the unit goes back with no obligation. There is no mail-in service — equipment must be brought in person to our service centre during working hours.
Likely causes
- Protection circuit tripped: DC on output or speaker short — The protection circuit has detected DC on the output, an overload or a short in the cable/speaker and is holding the relay open — the unit powers up, the display lights, but the relay never clicks. The Protection LED is often lit.
- Output relay contact oxidation — The speaker protection relay (Omron G2R, Takamisawa, Fujitsu) oxidises over time — contacts stop passing signal even though the relay clicks audibly 2–3 seconds after power-on. A typical age-related fault.
- Output transistors blown — The output pair (2SC5200/2SA1943 or equivalents) has shorted, placing DC voltage on the speakers, and the protection circuit holds the relay open indefinitely. Often only one channel is affected.
- Wrong input selected or Mute engaged — On AV receivers the remote Mute button, an active Zone 2, the wrong input selected (CD instead of HDMI) or Pure Direct enabled with no source attached all give complete silence while the front panel still looks alive.
- Stuck headphone-jack switch — Many amplifiers automatically mute the speakers when headphones are plugged in. If the mechanical contact in the Phones jack has oxidised or stuck, the unit thinks headphones are inserted and keeps the speaker output disconnected.
- HDMI handshake or DSP processor fault — An AV receiver fails to negotiate HDCP or CEC with the source, or the on-board DSP chip has lost its firmware — video passes through ARC fine, but audio is dropped inside the receiver. A factory reset or firmware reflash usually clears it.
- Dried-out electrolytic capacitors in the signal path — Coupling capacitors between stages lose capacitance with age, blocking signal flow. Especially common on equipment older than 15–20 years.
Try this first
- Try a different signal source (phone via AUX or another player) — if sound comes back on a fresh source, the amplifier is not the culprit.
- Check the selected input and Mute on the remote, turn off Zone 2 and Pure Direct, and make sure the volume is not at minimum.
- Plug headphones in and out a few times — an oxidised Phones-jack contact often releases the speakers again.
- Toggle Speaker A/B on the front panel and check the wires in the binding posts — no stray strand should touch the chassis or the neighbouring terminal.
- If the Protection LED is lit or the display is flashing, unplug the unit from the mains for 30 minutes, disconnect the speakers and try again with no load.
When to bring it in
If after swapping the source, checking inputs, mute and the headphone jack there is still no sound, or the Protection LED stays on, the amplifier needs bench diagnostics. We open the chassis, scope the signal path from input to output, measure the output-stage bias and quiescent current and test the relays and electrolytics. If the output transistors are blown we replace them as a matched pair with originals or proven equivalents; relays are swapped for fresh Omron/Fujitsu units and the output stage is realigned under load.
Fast on-site diagnostics. Warranty: 3 months.
Brands we repair
FAQ
Why customers choose SATER
- Tube amplifier and Hi-Fi repair. We work with valve circuitry that most service centres no longer touch.
- Vintage audio expertise since 1993. Radiotehnika, Technics, Marantz, Pioneer — we know this equipment from daily practice, not catalogues.
- Turntable restoration. Belt replacement, tonearm adjustment, motor repair — we bring turntables back to life.
- 30+ years of experience. The service centre has been operating since 1993.
- We serve all of Latvia. Electronics service centre in Riga — we accept devices from anywhere in the country.