[Test-Equipment] Hickok 288X signal generator

[Brian Burns]

Hello Pete,

Thanks very much for all the excellent information! I'm much relieved. I
never could get my mind wrapped around the concept of a "flow of holes",
much less the functioning of an IC, hence my self imposed limitation of just
working with tubes. Besides, working on solid state gear is much like
building a ship in a bottle, and I'm not all that well coordinated!

Cheers,

Brian

-----Original Message-----
From: Test-Equipment [mailto:test-equipment-bounces at mailman.qth.net] On
Behalf Of Pete Lancashire
Sent: Monday, April 21, 2014 1:18 PM
To: Discussion of Electronic Test Equipment
Subject: Re: [Test-Equipment] Hickok 288X signal generator

The pcb was labeled "Heath",

Its been added much later

>Texas Instruments IC's with numbers like:
>Z7647
>
>443-7

the 7647 is 1976, 47th week

443-7 is a Heathkit part number, in this case it is a 7490 TTL counter

One of the cross references that are on the web

 http://www.pestingers.net/heathkit_interface/Heathkit1/

>I'm not sure when the unit was made, but the IC's are surely around 50
years
>old, and I would guess are no longer functioning, and that replacements 
>are non-existent.

I would guess other wise, unless the parts we kept in a damp location, the
failure mechanisms for IC's around that time were less prone to long term
failures then some today. The bond pads, wires etc in most cases still gold.
Purple Plague was not a big problem in TTL. A killer will have been the
Kovar leads (mostly Iron) corroding, out gas/ion issues from the
plastic/epoxy packages, process contamination, and just poor handling in
general.

Since it is a Heathkit board, almost all the parts were common, and there's
many still around usually just for the asking.

-pete




On Sun, Apr 20, 2014 at 12:21 PM, Brian Burns
<brian at lessonsinlutherie.com>wrote:

> Hello All,
>
>
>
> I just acquired an Hickok 288X signal generator thinking that this old 
> timer would be entirely tube based, and hence within my pay-grade for 
> restoration.
> Imagine my surprise when removing it from its cabinet that the first 
> thing I saw was a printed circuit board with 5 integrated circuits! 
> Four were Texas Instruments IC's with numbers like:
>
>
>
> Z7647
>
> 443-7
>
>
>
> The pcb was labeled "Heath", contained all the circuitry for the 10, 
> 100, and 1000 kHz markers, and was clearly a stock part, factory
installed.
>
>
>
> I'm not sure when the unit was made, but the IC's are surely around 50 
> years old, and I would guess are no longer functioning, and that 
> replacements are non-existent.
>
>
>
> All of which leads me to the question of what to do with the old girl. 
> As it stands it's just a box of parts for me, but I hate to tear into 
> a well made piece of gear that might be restorable.
>
>
>
> As the man wired home on arriving for the first time in Venice:
>
>
>
> "Streets are full of water-please advise"
>
>
>
> Cheers,
>
>
>
> Brian
>
>
>
>
>
>
>
>
>
>
>
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