I am part way through doing something that I vowed to do one day, namely to 're-resistor' my AU-D11 II. I had ordered the required resistors in February 2015, and they had been sitting in their box in my workshop all this time. The standard resistors are a mix of mostly 'Carbon Film', but also some 'Carbon Composition', these are all being changed to Metal Film's. So far I have completed the Control Amp (read Pre-amp), but I am having a pause to listen and see what difference has been made by the changes. The amplifier seems more precise and clear, and is quieter noise-wise but you can only notice the reduced noise when using headphones. Overall I am pleased, but I want to listen some more before committing to do the rest.
Do you trust new resistors?
Something happened while I was working away on the Control Amp board which really surprised me. I was making the job that much harder for myself by measuring each resistor as it came out, and measuring the new ones going in, (just for my own interest). It was all going well until I removed a couple of 220KΩ resistors and checked them - they were very good, each reading well within spec at about 400Ω high. Then I checked the new resistors, 220KΩ ? - nope - how about 224KΩ, and another 227KΩ, and the worst one of all 254KΩ, with a 1% tolerance these should all have been 220KΩ +/- 2200Ω and none of them (50) were, they were all reading high. So I tried 2 other multimeters - exactly the same, all reading high. I went back to the old ones, still 220.4KΩ - and checked the meters with my resistance standard 1KΩ 0.01% - reads fine.
Still scratching my head I decided to complain to the supplier, and hopefully get some replacements. So I fill out a Quality Query form online with the relevant info - but hearing nothing I ring up the supplier. They were all ears until I told them I bought the resistors 3 years ago, the customer service representative says "sorry Sir we can't help you, our standard warranty is 1 year, but 3 years is out of the question". So I went through the '
resistors are supposed to be eternally stable, especially if not used' thing - and that I would send back the faulty ones for their inspection - they were having none of it. Lesson learned I suppose, but I am still stunned by the hard line taken for just £4 worth of resistors. There is no question of my ceasing to order from them, they are far too useful a supplier for me to get all bitter and twisted about the issue.
Sorry for the long post, thanks for reading - if you got this far.