Along the same line, is there a chance that you have a counterfeit 7490
chip? A lot of chips coming from Asia are marginal manufacturing
rejects or remarked circuit pulls that may have been mid-labeled.
Dave
On 3/9/2017 4:21 AM, JohnK wrote:
Very very good advice from Nick in these two posts.
Changing like-for-like or interchanging if easy is valid -
modifications aren't. [Unless you deduce something from a *temporary*
mod to allow you to fix the original problem.]
I have had to deal with the fallout from bad approaches: "We"
discovered that, in the Chinese factory, there was an 'engineer'
modifying the units that failed test until they worked or passed.
Things like changing the value of a resistor in a voltage divider that
supplies a ref voltage to a comparator making up for an IC with a
leaky input ( or a solder bridge to a different part of the circuit as
in one of the customer returns that I analysed). Eeek!!
John K
----- Original Message ----- From: "Nick" <[email protected]>
To: "neonixie-l" <[email protected]>
Sent: Thursday, March 09, 2017 1:37 PM
Subject: [neonixie-l] Re: Taylor Edge Nixie Clock Kit
...Also, reading your problem description isolates the issue to the
10s digits.
The 10s are driven by 7490s whereas the units are driven by 7492s. Do
you have the right chips in the right places?
I'd also try swapping round the 74141s between the 10s and units to
see if the problem moves with them - 74141s can fail....
--
You received this message because you are subscribed to the Google Groups
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send an email to [email protected].
To view this discussion on the web, visit
https://groups.google.com/d/msgid/neonixie-l/1b0cedd9-9b5f-30ef-7e8d-200e8eba5e5a%40davidspeckmd.org.
For more options, visit https://groups.google.com/d/optout.
