Alchemist Forseti APD15A RC Integrated amplifier

We recently had a customer present this faulty Alchemist Forseti integrated amp for repair – I’d guess this dates from the 1990’s and has been well looked after. It’s a bit of a bruiser as you can see from the extensive heatsinking!

 

Alcemist Forseti integrated amplifier

Alcemist Forseti integrated amplifier

Unfortunately it developed a DC fault on the loudspeaker outputs and destroyed the customers speakers, so it’s now in the naughty corner awaiting surgery.

Access to the internal circuitry is via the top panel, which is secured by 13 cap head screws.

alc2There are 13 screws to remove in total, an allen key is needed.

Alchemist Forsceti rear panel

Alchemist Forsceti rear panel

The rear panel has good connectivity for analogue sources (all line level, no phono input 🙁 but there are two pre-outputs to drive extra power amps should you need even more power.

Once the top panel is removed, this is the view of the printed circuit boards and power supplies – it’s very nicely laid out.

Alchemist Forseti amp main pcb

Alchemist Forseti amp main pcb

The Forseti is constructed as a dual mono design, which should give better channel separation and therefore improved stereo image – here is one channel’s output stage which employs two pairs of output transistors per channel – 2SA1302 are the PNP transistors and 2SC3281 are the NPN making a class B push pull output stage.

Forseti transistor output stage

Forseti transistor output stage

Each amplifier channel is fed power from it’s own dedicated power supply comprising 200VA toroidal mains transformer, bridge rectifier and four 10000uF/ 50V resevoir capacitors.

Forseti mains power supply is heavy duty

Forseti mains power supply is heavy duty

All of the the inputs are electronically switched by relay to keep signal paths extremely short for best possible sound quality.

Forseti relay switched inputs

Forseti relay switched inputs

The Forseti is a very well constructed amplifier which promises excellent performance – we will have to wait to hear this until we have diagosed and fixed any issues.

Facebooktwittergoogle_pluspinterest
This entry was posted in Hi-fi workshop, Top Off on by .

About Phil Glazzard

Phil describes himself as an 'audio nut from an early age', and is the director of the company as well as our in-house repairs engineer and custom installer. He takes interest in all music forms and spends most of his free time playing the drums, or geeking it up with PIC microcontrollers. He can't resist a gadget.

Leave a Reply

Your email address will not be published. Required fields are marked *