Sourcing Panaplex Displays (SP-252)

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B Gladden

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Apr 12, 2021, 8:20:48 PM4/12/21
to neonixie-l
Hello all just found and signed up for the board! Really interested in what you folks do here. 

Just found a neat Heathkit kit clock at a yard sale and I'm hoping to revive the little guy. I assume the thing needs these 45 year old capacitors replaced at some point, but my real issue is with these Panaplex displays. One display appears to be on it's last legs and another is completely dead.

I'd like to go ahead and swap in some "new" ones, but what I thought would be a simple trip to eBay turned out to be much more complicated. Does anybody have a source for replacing the SP-252 displays in here? I've checked with Sphere Research and they do not have any in stock.

Thanks in advance!

Bill Stanley

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Apr 12, 2021, 9:59:39 PM4/12/21
to neonixie-l
It may depend on the Heathkit clock you have. I have the original GC-1005 that uses the SP-352 tubes just fine. I do note that the 353 displays have more pins than sockets (pin bent out of the way) so perhaps the 352 is a superset of the 252. In the manual on page 20 it indicates that your display may have 2 extra pins that are simply bent out of the way.

In terms of available parts, I ordered 2 from ebay at:

Note that they do not test or indicate that they will work  "Sold as none (sic) working units, for parts"
One display worked fine while the other one had a metal "blob" in the middle of the E segment. It displays only 1/2 of that segment. YMMV

The good news is that current capacitors are smaller and probably have longer life than the original. You will probably want to replace C203 (2x20 uF 350V) and C204 (1200 uF 25V).
DigiKey would be a good source to check.

  -Bill-

Michail Wilson

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Apr 12, 2021, 10:29:37 PM4/12/21
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Hello B Gladden,

 

First, congrats on joining.

 

The 252 and 352 are basically the same except that the 352 has 2 keep-alive indicators which are not needed.  That is why they have the 2 extra pins that the manual and Bill mentions.

You ‘could’ even use a 752 if a must, although the resistors would best be changed to account for the difference in power requirements.

 

It’s unfortunate that the 352 (2 digit) are more expensive than the 353 (3 digit versions) which are less than half the price.

Example… the 352 is $30 on ebay.

The 353 is about $12 on ebay.  I have been buying them up nearly every day.

 

Another note on the caps.  I have seen units that people want to appear as original.  So, they drill out the original cap to fit in modern caps.

 

 

Michail Wilson

206-920-6312

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