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Re: help!? - plex thermal problem even with mod?

At 10:39 PM 7/7/97 -0700, you wrote:
>Hi Dan-
>you've asked about undo on the echoplex a bunch of times recently. I've
>been meaning to help you out, but haven't yet had a chance to get to it. I
>can get you a quick answer today:

i appreciate it.

>At 8:16 PM -0700 7/7/97, dan mcmullen wrote:
>>just saw the "undo == record" behavior on my new plex after having it on
>>for most of today!  has anyone else seen this?
>>the only twist to my mod was that the adc chip in my plex is socketed, 
>so i
>>just bent the pin out rather than clipping it.  this should work, yes?
>two possible problems:
>a) you bent up the wrong pin. check the diagram on the website to make 
>you got it right.
pretty sure on that one.

>b) it is July and you live in the Northern Hemisphere, where it is the
>middle of a hot summer, and your echoplex was on all day in a poorly
>ventilated room with a high ambient temperature. If that is the case, take
>the advice of our friends in equatorial climates, and use a fan.

as a last resort, i'll do that.  alternately, is there one component in
particular that is heat sensitive?  the adc?  i've glued heat sinks on
particular chips in the past.  this problem hasn't recurred yet, but it
wasn't all that hot in the house at the time.

>>ps- figured out that the undo led goes on the 2nd loop after recording if
>>feedback is less than 100%: you can undo the gain reduction for each 
>>:-)  seems like this could interfere with undoing overdubs & such when
>>feedback is <100% though.  is there any way to disable this behavior?
>Reducing feedback is changing the loop in exactly the same way as Overdub.
>Undo takes away changes made to the loop, whether they are made by overdub
>or feedback or whatever. There is no way to change that or have undo
>differentiate between one kind of change and another. (boy, that would be 
>complicated user interface!) Take another look at the section in the 
>that explains how memory and undo are related to get a better 
>of this. As you are probably noticing, undoing the gain changes is pretty
>useful anyway!

sometimes yes.  other times it can make it hard to predict what undo will
(un)do.  also, it means that 'undo' memory gets used up rather quickly when
feedback is reduced.  i see the difficulties though.

mostly, i was surprised to see undo kick in w/ reduced feedback.  it seems
that there have been other times (after multiply?) when undo became active
without obvious reason.  is there a comprehensive list of undoable events?
are there other surprising undoables?

just what you need: more questions with too little time to answer them!  

>hope this helps,

it does.  thanks.


dan mcmullen                               don't worry - pay attention
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