An old Cambridge Audio A500 amplifier came in for repair that wouldn’t switch on. The fault was tracked down to a failed mains transformer.
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Amplifiers often have circuit diagrams on the Internet but I’m yet to find one that states any useful information about the mains transformer and this was no exception. Being a very old amplifier Cambridge couldn’t / wouldn’t give me the information so some working out was required to find a suitable replacement.
The photo below shows the old and new transformer.
Before buying a replacement transformer the amplifier power transistors were checked as they’re unusual (SAP15N and SAP15P) and obsolete.
The power transistors are darlington devices with additional resistors and diodes in a five pin package. They tested OK with a multimeter so a new transformer was fitted that brought the amplifier back to life.
YouTube video of the repair is below.
If you have a Cambridge Audio amplifier or other electronics equipment you need repaired please Contact me for a quotation.
Related repair: Cambridge Audio A5 Amplifier Repairs