Reposting with IMPROVEMENT spelled correctly in the title so this letter can be easily searched. Sorry for that. Model 9 Crosstalk Mmprovement Hello to everyone. This is an easy fix. On each of the two ICs on the M9 (one a TLO74, One a TLO72), you will find two small blue capacitors flanking those components which are unmarked (meaning there is no C number - as in C1, C2, etc. - designator). SO two per IC for a total of 4 caps. On the M9 all four of those guys are by the edges of the PCB. There are a few other small blue caps on the board, but those have designator numbers and are in the pf range, somewhere around 22pf (I'm at my g/f's place, not around my schematic reference or system, please pardon my 52 year old memory). These shouldn't be changed. They merely kill potential oscillation in the feedback loops of the gain buffers (wouldn't ya know it, hardest thing in analog is to get a oscillator to do it's thing properly, yet it will happen all over the place were you don't want it so you have to through components to it to stop that from happening). Until quite recently those four caps were .01 uf, marked "103" on the cap itself. They need to be removed and replaced with .1 mf, which is marked "104". That's it. Not that bad, five minute job and will cut the crosstalk down a lot. We've been shipping the m9 with this new part since this was discovered about a month or so ago and are now using .1's on all of our modules. For a reference of how to read the value of small capacitors, see this: http://www.electronics2000.co.uk/data/itemsaf/capconv.php CAPS are marked with the Picofarad value. A .01 microfarad is 10,000 pf - their marking reads 103, which visually must be read as 10 plus 3, meaning three extra zero's after the initial 10 (10,000). .01's = 100,000pf or 10 plus 4 - four extra zeros after the 10.
Message
Model 9 Crosstalk Improvement
2008-12-20 by (i think you can figure that out)