[NJARC] Mega 328 Tester

[Aaron Hunter]

I read with interest the comments from our learned radio collector 
experts.  So I decided to run a test of the multi tester against my 40+ 
year old Heathkit capacitor testor.

First let me preface this with my electronic training.  I graduated from 
Philadelphia Wireless Technical Institute 50+ years ago.  My grades were 
not stellar, so I won't go into them.  What I did manage to understand 
and learn, I've forgotten years ago.  I now drive a school bus, so you 
can see how my electronics background has paid off.  LOL

I fired up my Heathkit IT-11 and tested some electrolytics and compared 
the results with the multi tester.  The first thing I noticed this time 
was I had the Heathkit switched to non-electrolytic for the leakage test 
the other day.  This is why two of the dented electrolytics tested bad 
then but good when forced up to a working voltage of 450 with 500 Volts 
applied for a minute or two.  The other two dented capacitors were also 
forced to the working voltage, again using 500 Volts.  They took several 
minutes to reach the working voltage, one getting warm and the other 
showed signs of leakage, didn't take notice if it was warm or not.

The first three tests were with the Heathkit and bringing the capacitors 
up to the working voltage, then testing with the multi meter.  (Make 
sure to short the capacitor before inserting in the multi meter.)  I 
reversed the next two tests, using the multi meter first to see if there 
was a difference in readings after bringing the capacitor up to working 
voltage with the Heathkit.

Notice on the 5th capacitor, I took multiple readings with the multi 
tester and got varying results for value.  I couldn't find the specs. 
but it appears the 4th digit is meaningless and the 3rd questionable.  
To me, it seems to have an accuracy (regarding reproducibility) of about 
+- 10%.

The last two tests were with capacitors of the same value but different 
manufacturers.  They had even higher ESR values, which I don't know if 
that's good or not.

I still question reforming capacitors.  Did you recheck the capacitor 
after it sat for several days with no voltage?

Years ago, when my Sansui 5000 was about 8 years old, one of the channel 
fuses popped.  When I inserted another fuse, it worked fine until the 
next day when it would pop the fuse or take out the output transistor.  
I found if I inserted a resistor into the fuse socket first, I could 
then replace the fuse and use it off and on for the day, but the next 
day would have to do the resistor trick again.  This made for difficult 
normal trouble shooting techniques, so I pulled the mini electrolytics 
on the problem board.  Using the technique mentioned in an earlier 
email, I watched the current draw when voltage was applied and found the 
culprit.  Once it got up to operating voltage, voltage could be applied 
off and on all day and the capacitor would charge quickly each time.  
But let it sit for a day and you'd start all over again.  So again I 
ask, were those reformed capacitors rechecked after a few days to see if 
they needed reforming again?

I hope my chart comes across, otherwise this email was all in vain.

Aaron Hunter

PS  I threw out the dented electrolytics!
>
> On Wed, Dec 30, 2015 at 11:31 AM, Aaron Hunter <ahunter01 at comcast.net 
> <mailto:ahunter01 at comcast.net>> wrote:
>
>
>     _________________________________________________________
>     I hope everyone realizes when checking capacitors, only the value
>     is checked, not the leakage current.
>     I had some fairly new electrolytic capacitors that had dents in
>     the cans.  I checked them with the checker and a good capacitance
>     value was shown.  When I check them with my HeathKit capacitor
>     checker, all dented capacitors had high leakage current.  The only
>     one of the group to escape a dent tested good.
>
>     Aaron Hunter
>

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