Dumpster Dive audio amplifier

[seanhaz]

got this Marantz audio amplifier for free from a end of year student rubbish drop off.
forgot to take a before picture of it but it was really dirty

took it apart and temporarily hooked up a mains cable to test run it, had to put a new mains cable in it because at the rubbish drop off site they chopped off all the appliance cables for safety reasons.

first fault i found was no display on the LCD screen, turned out to be an easy fix which was just the incandescent back lights had blown, replaced them with LED's


The next fault was the plastic volume buttons broken and by pressing either of the volume micro-switches causes the volume to increase which is probability how the volume button got broken lol.
first i tested the continuity of the micro switches and they were both around 0.5M ohm when on, so luckily i had a few spare ones laying around and replaced them and now works perfect, just need to try find a new plastic volume button.


next problem is the amplifier has a "two system" speaker output and the first "system" works fine, but when push the button to select output to both "systems" i get no output. have tested the switch and all the contacts are fine and cannot see anything obvious, so im a little bit stuck on this fault so any ideas are very helpful, or is it still a bit of a vague fault with the info given?

so after that i decided next to strip the whole thing down and clean it out as it was pretty dirty and needed to repair a break in the plastic on the front panal


pushed the break in the plastic back in are straightened it out and glued it back together


reassembled the unit and gave it a test run and decided to add an IEC socket to the rear of the unit to replace the mains cable that was cut off


and heres the finished piece(just need a new volume button)


so all in all a great free score with little problems (well one im yet to solve so any help is welcomed)

oh and the main thing, the sound quality is good

[David_AVD]

Did you have two pairs of speakers connected when you pressed the "both" switch?

Some cheaper units simply put the speakers in series when A & B sets are selected together.

This is so the amplifier won't have the paralleled impedance (too low) of the two speaker sets.

[calexanian]

Good luck with that one.. They are not that great to begin with.

[seanhaz]

Did you have two pairs of speakers connected when you pressed the "both" switch?

Some cheaper units simply put the speakers in series when A & B sets are selected together.

This is so the amplifier won't have the paralleled impedance (too low) of the two speaker sets.

 that was the case =) thank you