Rotel A14MKII Repairs

Rotal amplifier in for repair

Rotal amplifier in for repair

This Rotel A14MKII was wired up for a 110v mains supply and was accidentally connected to the UK 230v supply.

By connecting twice the specified input voltage to the mains transformers their output voltages will be doubled, potentially causing all sorts of damage to the circuitry they power.

It also risks burning out the transformer primary windings.

If you need your hifi repaired please contact me for a quote. Equipment can be shipped to me or dropped off.

Rotel A14MK2 being repaired
Rotel AV14MKII being repaired

Fortunately the CPU board and front panel display with all the expensive voltage critical digital parts such as the microprocessor survived, probably due to everything on that board running from voltage regulators that had input voltage limits high enough to cope with the over voltage.

The front panel display, buttons and LEDs were working but the amplifier was no longer working as an amplifier.

Below is a link to my electronics repairs YouTube channel where I take a look at this faulty amplifier.

In this amp the microprocessor is able to isolate the power to the main amplifier circuitry via its timed auto shutdown feature.

I presume this is also used when putting it into standby. The fault was that this feature was permanently activated, so the main amplifier board had no power.

The fault was due to a failed transistor used in the power supply for the shutdown relay.

Fortunately the transistor failed in a way that switched the amp off rather than on, thus minimizing the risk of further damage!

After I’d repaired it I rewired the transformers (main and standby) to operate on the UK 230v supply.