[time-nuts] General Technology Corp model 304b

Ed Palmer ed_palmer at sasktel.net
Mon Apr 30 03:47:04 UTC 2012


Hi Don,

On 4/29/2012 6:41 PM, Donald Henderickx wrote:
> On 4/29/2012 6:27 PM, Ed Palmer wrote:
>> Yes, there's a partial copy of the manual online.  It's missing a few 
>> schematics, but is otherwise complete.
>>
>> http://sundry.i2phd.com/ServiceManual_304b.pdf
>>
>> Ed
>>
> The bottom pin is not chassis ground,on this unit.

The bottom pin (pin B) is connected to circuit ground which is connected 
to chassis ground on my unit and the schematic confirms it.  That could 
be why you have to ground that pin to make your unit work.  There 
appears to be a broken or missing ground somewhere in your unit.

> The foam looked original before in crumbled.

That's good to know.  Thanks!

> The 400v cap in the ignitor circuit dumps into the primary of a 
> autotransformer, from the spark I observed I would i would guess 10kv> 
> so I do not think intimate contact is necessary

I looked right at the autotransformer on the schematic and still didn't 
see it.

> You asked about lamp voltage test point not lamp heater test 
> point,that is what confused me. I will check it when I power it back up.

You're right.  Sorry for the confusion.  This has not been one of my 
better days.

Ed


>>
>> On 4/29/2012 5:18 PM, paul swed wrote:
>>> Curious is the manual online?
>>> Would be interesting to look at.
>>>
>>> On Sun, Apr 29, 2012 at 6:33 PM, Ed Palmer<ed_palmer at sasktel.net>  
>>> wrote:
>>>
>>>> Hi Don,
>>>>
>>>> On 4/29/2012 2:54 PM, Donald Henderickx wrote:
>>>>
>>>>> On 4/29/2012 1:36 PM, Ed Palmer wrote:
>>>>>
>>>>> Thank you Ed,Paul,and Marco for the reply's
>>>>> The foam I was referring to is or was around ceramic base  were the
>>>>> igniter wire goes . Yes my wire also broke loose however I do not 
>>>>> want to
>>>>> disassemble any more than I have to. I think that just inserting 
>>>>> it back in
>>>>> to the hole and securing in some way should work. I do not know 
>>>>> what the
>>>>> potential is but I have seen a spark jump at least an eight of an 
>>>>> inch.
>>>>>
>>>> The igniter wire has to be connected to the base of the lamp.  The 
>>>> patent
>>>> explains it quite well.  Just inserting it into the hole in the 
>>>> ceramic is
>>>> unlikely to work.  I don't know what the voltage is, but the 
>>>> capacitor that
>>>> stores the voltage is rated for 400V.
>>>>
>>>> Does the foam look original?  It definitely isn't on mine so I 
>>>> wasn't sure
>>>> if it was supposed to be there or not.  The patent describes how 
>>>> the base
>>>> is the coolest part of the bulb.  I don't know if a foam covering is
>>>> appropriate.
>>>>
>>>>   Tell me about the lamp voltage test point. My manual has no 
>>>> mention of
>>>>> it? Were is it located?
>>>>>
>>>> All the test points are described on page 5-3 of the manual.  The lamp
>>>> heater test point is the sixth one from the top.  Ground is the 
>>>> seventh
>>>> point.
>>>>
>>>>   In you first posting I think you mentioned some grounding 
>>>> problems. On
>>>>> this unit there is a three pin amp connector on the rear on mine 
>>>>> the bottom
>>>>> pin -20 must be grounded or the unit will not work. The red light 
>>>>> will come
>>>>> on very bright but nothing else works.I believe you can also 
>>>>> ground the +20
>>>>>   this allows this to work in various ground polarity systems IE 
>>>>> telco
>>>>> systems +ground. Perhaps I am wrong.
>>>>>
>>>> Do you mean the 3 pin round connector on the back?  That's for an 
>>>> external
>>>> DC power supply.  It has no other function and grounding the bottom 
>>>> pin
>>>> (which is ground) shouldn't make any difference.
>>>>
>>>> Ed
>>>>
>>>>
>>>>   I have Hp113,Hp115 that caution you on the ground polarity of the 
>>>> systems
>>>>> you are installing them in. I think all the -20 floats from 
>>>>> chassis ground
>>>>> until they get to that rear plug.
>>>>> Thanks for foam an fiberglass suggestions.
>>>>>
>>>>>> Hi Don,
>>>>>>
>>>>>> You know that we're going to be swapping many emails, don't you? :-)
>>>>>>
>>>>>> On 4/29/2012 11:16 AM, Donald Henderickx wrote:
>>>>>>
>>>>>>> After following Ed Palmer's thread on 304b restoration,I was 
>>>>>>> inspired
>>>>>>> to get my GTC (tracor) 304b ser#279 going.  It seems that the 
>>>>>>> failure of
>>>>>>> this unit was the break down of the foam that was wrapped around 
>>>>>>> the vcxo
>>>>>>> located inside the control box. The vapors or the moisture the foam
>>>>>>> collected corroded the steel fasteners and caused the switches 
>>>>>>> to become
>>>>>>> intermittent.
>>>>>>>
>>>>>> The foam around my OCXO is still in great shape.  Still spongy and
>>>>>> providing lots of holding force for the OCXO.  My unit is serial 
>>>>>> #449.
>>>>>>
>>>>>>   The replacement of the foam in the control box is not that much 
>>>>>> of a
>>>>>>> problem,what I need help with is what to use around the Rb lamp 
>>>>>>> base. The
>>>>>>> foam has turned to powder.
>>>>>>>
>>>>>> Do you mean foam around the back end of the lamp where the wire lead
>>>>>> comes out or the foam that surrounds the reflector (#16 in the 
>>>>>> picture in
>>>>>> the patent that describes the lamp (3311775))?  My #16 foam is 
>>>>>> really solid.
>>>>>>
>>>>>>   Should I try Home foam sealant? The cell's ,of this seem about 
>>>>>> the same
>>>>>>> as the old foam.Will it take the heat?Should I make a fiberglass 
>>>>>>> cocoon to
>>>>>>> put around the lamp base.
>>>>>>>
>>>>>> Read the fine print on the can.  It may list the maximum temperature
>>>>>> rating.  I'd try a fiberglass cocoon first just because it's easily
>>>>>> reversible if it doesn't work.  When your unit is running is the 
>>>>>> lamp test
>>>>>> point voltage correct?
>>>>>>
>>>>>> Ed
>>>>>>
>>>>>>   The unit now achieves lock in about an hour. The only other 
>>>>>> thing I did
>>>>>>> was to replace the caps in the main supply.
>>>>>>> Any thoughts on the insulation?
>>>>>>> Don H



More information about the time-nuts mailing list