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9200 Clock Problem - 2nd Time

(26 posts)
  1. Biggles

    Biggles

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    How many people have failed to fix this problem and fitted a replacement board board at a cost of £32 ?

    Presumably none that have read my instructions and posted, or at least they haven't posted as such. If someone had a problem I tried to help them out.

    Why is there a video on YouTube on how to replace the board?

    I'm sure PCRowan was just trying to be helpful, he has at least now linked to my instructional thread on this forum, originally he didn't. There is much more feedback on my original DS thread.

    On my card the "super capacitor" is a battery.

    That's an interesting one. Was your 9200 second hand, is it possible someone has tinkered with the board before you got it?

    Why is this topic so hard to find with the most common search terms?

    My original DS thread comes up top of the list with a Google search of '9200 clock problem', PCRowan's video second.

    | Wed 25 Sep 2013 10:15:46 #21 |
  2. aldaweb

    aldaweb

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    A search of this forum for 9200t clock problem shows 2nd item in relevant posts as this FAQ item My 9200t shows --:-- in Standby (link)

    I don't see any benefit in this discussion continuing in this vein. I am minded to lock the thread if it continues.

    | Wed 25 Sep 2013 18:06:39 #22 |
  3. Biggles

    Biggles

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    aldaweb - 51 minutes ago  » 
    A search of this forum for 9200t clock problem shows 2nd item in relevant posts as this FAQ item My 9200t shows --:-- in Standby (link)
    I don't see any benefit in this discussion continuing in this vein. I am minded to lock the thread if it continues.

    Please do, I really don't have the time for arguing the toss about a problem that has been solved and proved to have been solved many times over.

    | Wed 25 Sep 2013 19:01:06 #23 |
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    Pottsy

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    I have never said that your fix doesn't work. I think that your explanation of a mysterious contamination that takes 5 years to have any effect, is just a theory. Why do all the millions of RTCs in the cheapest of domestic equipment not suffer this contamination. Are Humax circuit boards so poorly made as to be the only ones to suffer this problem?

    When the oscillator stops for whatever reason, the RTC chip is sitting there powered by the mains supply or, when the board is unplugged or mains lost, powered by the supercapacitor or battery, (it really is irrelevant which). The oscillator will be latched up. As you say the input pin is a very high impedance and will just drift until the output hits a supply rail and latches up. The oscillator will not restart until the power is removed or the input is pulled in the opposite direction by what? Static electricity, a scope probe, cleaning? Power cannot be removed without disconnecting the power source.

    Why did the oscillator stop? Why did cleaning not fix my board a 2nd time? Remember the other members who started this topic and the title.
    I don't have a supply of duff boards to test these theories. I simply reported my experience that replacing the crystal fixed my board.

    My complaint was that search terms on this forum did not find this topic -- not on the internet.

    Enough

    | Wed 25 Sep 2013 19:15:39 #24 |
  5. aldaweb

    aldaweb

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    Pottsy - 8 minutes ago  » 
    My complaint was that search terms on this forum did not find this topic -- not on the internet.
    Enough

    You obviously did not take the time to search the FAQ section or you would have found the FAQ item I linked to above, which could also be found by a search of the forums.

    Thread locked

    | Wed 25 Sep 2013 19:26:30 #25 |
  6. aldaweb

    aldaweb

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    Biggles has requested the following to be posted to correct assertions made in the above posts.

    With reference to the second paragraph in post #24 I would like to point out that this is not the behaviour of the circuit during the clock failure that my repair instructions refer to. Also there is no ‘kick-start’ required to restart the oscillator, it runs freely once the problem contamination has been removed. While the affected part of the circuit is high impedance (I used the word sensitive in my instructions due to the intended audience) I certainly did not say or imply “and will just drift until the output hits a supply rail and latches up” because it doesn’t.

    In a recent PM to me from Pottsy he has revealed that the cleaning fluid he used was a professional product designed for cleaning components, switches and printed circuited boards. I would not expect this type of product to remove the contamination causing the clock failure and would urge the use of the cleaning agent I recommend. I used ethanol but surgical spirit (mainly ethanol according to the bottle I looked at in Boots) has been used successfully by many and is probably the best alternative to pure ethanol. I would expect methanol, isopropanol and methylated spirits (denatured alcohol or household meths) to also work. Household meths is cheap, is mainly ethanol with additives to make it unpleasant to drink and sometimes dyed purple as a warning.

    As an additional help, after cleaning the clock end of the board with cotton buds and a small brush it might be advantageous to hold the board clock end down and brush on more cleaning fluid to effectively swill down the cleaned area, shake off the excess and blow dry with a hair dryer. Obviously only lightly warm the board rather than toasting it.

    Biggles

    | Tue 1 Oct 2013 18:32:34 #1 |

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