{"id":4979,"date":"2016-06-19T16:52:39","date_gmt":"2016-06-19T14:52:39","guid":{"rendered":"http:\/\/www.knottinbotswana.com\/?p=4979"},"modified":"2016-06-19T16:52:51","modified_gmt":"2016-06-19T14:52:51","slug":"rotel-repair","status":"publish","type":"post","link":"http:\/\/www.knottinbotswana.com\/index.php\/2016\/06\/rotel-repair\/","title":{"rendered":"Rotel Repair"},"content":{"rendered":"

Back in the mists of time (1997) when compact discs ruled and I had access to second-hand CD shops I blew a portion of my student loan on a cheap(ish) Rotel stereo amplifier<\/a>, Technics CD player<\/a> and KEF Coda 9 floor standing speakers<\/a> (the KEFs<\/a> were particularly spectacular with built-in rear-ported passive subs).<\/p>\n

\"My<\/a>
My first hi-fi, student days.<\/figcaption><\/figure>\n

A few years ago, after importing it to Botswana (thanks, Mum), the amplifier started giving me gyp and it got consigned to a cupboard, then I felt the need for noise again and decided to try and fix it.<\/p>\n

But back to my hi-fi history… the equipment lived with me through my 2nd and final student years in a couple of Victorian-era houses (oh, the joy of suspended wooden floors – sorry guys), but I left them behind when I emigrated.<\/p>\n

When my mum came to visit for the birth of my daughter in 2003 I was able to persuade her to pack the amp and CD player, sadly not the speakers (10.5kg…) though.<\/p>\n

They ran paired with some no-name Chinese speakers for a couple of years but something went wrong and the amp started producing terrible hiss and unpleasant crackling until the speakers died.\u00a0 On autopsy the capacitors on the speaker crossovers<\/a> had failed, whether this was caused by the amp, Chinese quality control or capacitor plague<\/a> I don’t know.<\/p>\n

When I started in Gaborone I noticed a set of Jamo speakers for sale in Game, at a mildly silly price.\u00a0 They sat there for months, un-moving (people here like their home-cinema systems with blingy flashing lights, not hi-fi separates), until soon after Christmas I saw they had been put on special… finally, a manager had realised they were dead-stock.\u00a0 I swooped.<\/p>\n

And the amplifier ran fine for a few days before starting to play silly buggers again, finally dropping the left channel completely.\u00a0 I did some reading and found various possible causes: diodes, capacitors and so on.\u00a0 Time for some exploratory surgery.\u00a0 Armed with a circuit diagram I opened the belly of the beast and started multi-metering everything, until I found diode D601 that seemed not to be doing what it was supposed to.<\/p>\n

A local electronics store luckily kept stock of the 1N148 diode so I bought one, then tried to fit it… after managing to briefly melt the solder holding the diode while burning my fingers I decided electronics repair was not my thing and went to the professionals, who tested the diode themselves and found it to be fine… so I came home, played some music with the covers off and found it to be… fine.\u00a0 Props to Maja Enterprises<\/a> on Lejara Road, Broadhurst (opposite and up a bit from Barclays) for not laughing, and for having an astounding range of electronic components and a shop largely full of knackered cathode-ray TV sets.<\/p>\n

So, how to put it back together with all those different length screws? Luckily I had put the top and bottom screw sets in separate bags, but hadn’t made a note of which lengths went where.<\/p>\n

Luckily the bottom screws were all in prime number combinations with 3 long, 5 medium, 2 short and 2 fat.<\/p>\n