Sold: Gorgeous GFA-545 II

hoppesbrain

10 years ago

Sold to Maxim in NYC!

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And the amps just keep on rolling! This is the nicest GFA-545 II I’ve ever restored. Cosmetically, It’s pretty close to perfect! The face is nearly flawless. There’s just one scratch that I’ve touched-up on the top cover, towards the back, and a two barely noticeable scuffs on the sides. Click on the photos to see it in hi-res. Overall, it looks just about brand new.

But it’s better than brand new! This is a complete tear-down and restoration using every trick I’ve learned about Adcom amplifiers.

Power supply capacitors upgraded from 10,000uF to 15,000uF Panasonic TS-HA 105C for higher current reserves, longer life, lower DCR and more ripple current capacity.
All electrolytic capacitors replaced with carefully selected audio-grade capacitors from Nichicon and Panasonic. Signal capacitors upgraded to WIMA MKS.
Transistors in the critical input stage are matched for gain. This step is important to assure low DC offset at the output, and low distortion.
Circuit boards cleaned and all solder joints re-flowed and inspected.
New power switch and spark-supressor capacitor.
New and higher-rated surge-protection MOV. I replace them even when they test OK. They’re known to develop latent failures due to exposure over time to moderate spikes.
Sealed Bournes trim-pot installed for precise bias adjustment and better reliability.
Heat sinks added to the transistors in the thermal protection circuit. (These are known to run hot and burn the board.)
Emitter resistors changed from 5% tolerance sand-cast types to mil-spec DALE LVR 1%. These are more reliable, and frankly, prettier.
25A bridge rectifiers replace original 10A.
Heavy-duty gold-plated binding posts.
A high-quality snubber capacitor is installed across the AC power input to reduce RF interference and reduce noise.
All wiring is obsessively neatened.