[time-nuts] HP 5275A

Adrian Godwin artgodwin at gmail.com
Sun Nov 6 18:48:59 EST 2016


Glenn,

I think you're describing what Robert has photographed.

There are some of those packages, but they're the 2N1373 driver transistors
and have a smaller mounting hole. I dismounted Q2 and found it's really a
2N2556 (but still T05) and similarly mounted, but in a bigger stud. The
threaded part is wide enough to hold the package itself.

Since the insulating washer can now be kept safe, I can probably just punch
or heat the T05 out (it has a hole right through the stud).

On Sun, Nov 6, 2016 at 11:16 PM, Glenn Little WB4UIV <
glennmaillist at bellsouth.net> wrote:

> A 2N1038 is in a TO-5 or TO-11 package.
> A 2N1038-2 is a modified or selected part.
> Is this transistor pressed into a hexagonal bushing that is about 1/2 "
> long with a 10-32 threaded stud for mounting?
> If so the bushing/heatsink is part of the transistor.
> A google search for 2N1038 will show this this transistor and a similar
> one with the integral heatsink.
>
> Glenn
>
>
>
> On 11/6/2016 5:46 PM, djl wrote:
>
>> Just homemade opto-isolators. Used in choppers, too. The transistor was
>> indeed bonded to the heatsink.  Just replace the whole thing with a
>> 3-legged regulator? or simply a modern PNP t0-220 with a little heat
>> sink on it.
>> 73, Don
>>
>>
>> On 2016-11-06 15:15, paul swed wrote:
>>
>>> Don't know what to say on the transistor. It may have been actually made
>>> that way. They did lots of things back then. Yes familiar with the bcd
>>> decoder its used in the 5245 class counters also. I think someone was
>>> doing
>>> some funny stuff at lunch time to come up with that. It was the 60's
>>> after
>>> all.
>>> How about some pix of a 9815 calc. That would be pretty neat.
>>> On really old stuff if you can't find the part needed its pretty easy to
>>> replace the whole function with modern answers. I know it sort of breaks
>>> the original mode but for me at least its a case of getting it going.
>>> Regards
>>> Paul
>>> WB8TSL
>>>
>>> On Sun, Nov 6, 2016 at 1:59 PM, Adrian Godwin <artgodwin at gmail.com>
>>> wrote:
>>>
>>> Slightly off-topic, as this is a general repair question. But it's a
>>>> TIC.
>>>>
>>>> I'm repairing a 5275A timer (all-discreet count logic to 100MHz, neon
>>>> bulb
>>>> display, a most amazing bcd to decimal decoder made from neons and LDRs,
>>>> 1-2-2-4 decade counters ..) and the current problem is a 2n1038-2
>>>> germanium
>>>> T05 transistor in the power supply.
>>>>
>>>> It's mounted in an aluminium bush which is then isolated from the
>>>> chassis.
>>>> I don't think the bush is also a collet but I can't see how to remove
>>>> the
>>>> transistor. It resists ungentle pushing .. should I push it with a
>>>> hammer ?
>>>> Or is there a kinder way ?
>>>>
>>>> (I'm hoping to eventually put this into a system with a 101A
>>>> oscillator and
>>>> a 9815A calculator to measure the ADEV of a Boule electric pendulum
>>>> clock).
>>>> _______________________________________________
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>>
>>
> --
> -----------------------------------------------------------------------
> Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
> Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
> QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
> "It is not the class of license that the Amateur holds but the class
> of the Amateur that holds the license"
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