hifi repair

AV Receiver repair – Yamaha RX-V450

by
AV receiver repair

This AV receiver repair, a Yamaha RX-V450, was completed on a fast turnaround for a local radio producer who needed it in time for a show. It’s got 6x85W channels and more inputs and outputs than you can shake a stick at.

Although I’m well versed in solid state electronics, this is the first AV receiver I’ve worked on, because most of my work is on musical instrument amplifiers.

The fault was with the power supply and is a known design flaw with the otherwise reliable unit. Over time, power surges can damage a 600V capacitor that resides in the soft start circuit. This might sound surprising when UK mains is 230V, but audio equipment should be designed to cope with 1kV or 4.5x the rated mains voltage to withstand surges. I replaced the device with a 760V capacitor, which was the biggest part that would fit in the available space. I added epoxy glue to prevent the larger part becoming a vibration risk. AV receiver repair

The amp was dropped off on the tuesday and the repair completed by the thursday. Just one hours work, with a short break for 24h turnaround on the new part.
The repair was completed within the first hour and returned quickly to the customer, who then brought me two other AV receiver repairs! He’d not been having much luck with them!

If you have an AV receiver repair, please let me know and I’ll see if I can help.

Hifi Repair – Restek Charisma

by

I don’t normally ‘do’ hifi – the construction often makes hifi repair inconvenient, and I don’t get to the opportunity to rock out when the repair is finished. However I took this hifi repair on for an associate who was very helpful to the Engineering team I work with in my ‘day job’. It’s a Restek Charisma – ebay tells me its worth what I’d call ‘silly money’!

The amp quite simply wouldn’t turn on.

Medium High end linear Hifis often have what’s called a ‘soft start circuit’. These prevent a massive inrush of current into a highly spec-ed transformer, the like of which you wouldn’t see in a guitar or bass amp, though you may be familiar with the ‘dong’ that you get when you turn on a powerful bass amp or linear PA – that’s the sound of the current vibrating the mains transformer. This soft start circuit uses another small mains transformer to power a couple of relays that then allow current to pass from the meaty mains transformer. This small transformer died resulting in a complete lack of anything. Replace the transformer and we’re good to go again as seen in all the pretty lights on the picture.

If you have a hifi repair, please do get in touch though I’m afraid I don’t always take them on.