[Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)

[GGLL]

    I've forgotten to add, that you must realign the driver and final 
grid section for the upper bands (best if you perform a complete RF 
re-alignment as per manual), where you may note the worst tracking 
difference after C13 capacitor change.

Good luck
Guillermo - LU8EYW.

GGLL wrote:

>    Are your final tubes fine after C13 short?; that failure will turn 
> very positive final tube's grid bias, which causes an indeed high 
> plate current. Check them before you go to the shop. If I don't miss, 
> C13 was a 100 pF rectangular old style mica cap. You could replace 
> them with two 47 pF, 500V NP0 disc ceramics in parallel as I did in 
> several 101's with good results.
>
> Best regards
> Guillermo - LU8EYW.
>
> Jerry Pittman wrote:
>
>> Correction!!!  Sorry Rick,  I spoke to soon.  I pulled the C13 cap 
>> from the
>> circuit and found that it had shorted.  You were dead on for the 
>> diagnosis.
>> Now to go to the electronics shop tomorrow.
>>
>> Thanks a Million!!
>> 73 Jerry
>> WD4OIX
>>
>> ----- Original Message ----- From: "Jerry Pittman" 
>> <jerryp49 at worldnet.att.net>
>> To: "R_Davis" <WD8JJA at arrl.net>; <yaesu at contesting.com>
>> Sent: Sunday, February 15, 2004 5:59 PM
>> Subject: Re: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
>>
>>
>>  
>>
>>> Thanks for the tip Rick.  I checked that cap and it appears okay, so 
>>> the
>>> search goes on.
>>> Jerry
>>>
>>>
>>> ----- Original Message ----- From: "R_Davis" <WD8JJA at arrl.net>
>>> To: <yaesu at contesting.com>
>>> Sent: Saturday, February 14, 2004 12:41 PM
>>> Subject: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
>>>
>>>
>>>   
>>>
>>>> Check the coupling capacitor, C13, between the 12BY7A and the finals.
>>>> Rick, WD8JJA.
>>>>
>>>> ----- Original Message -----
>>>> From: <yaesu-request at contesting.com>
>>>> To: <yaesu at contesting.com>
>>>> Sent: Saturday, February 14, 2004 12:00 PM
>>>> Subject: Yaesu Digest, Vol 14, Issue 9
>>>>
>>>>
>>>>     
>>>>
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>>>>> Today's Topics:
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>>>>>   1. Problem in FT-101E -100v Circuit (Jerry Pittman)
>>>>>
>>>>>
>>>>> ---------------------------------------------------------------------- 
>>>>>
>>>>>
>>>>> Date: Fri, 13 Feb 2004 12:41:26 -0500
>>>>> From: "Jerry Pittman" <jerryp49 at worldnet.att.net>
>>>>> To: <yaesu at contesting.com>
>>>>> Subject: [Yaesu] Problem in FT-101E -100v Circuit
>>>>> Message-ID: <006e01c3f258$9b485ac0$6101a8c0 at JerryPittman>
>>>>> Content-Type: text/plain;
>>>>> charset="iso-8859-1"
>>>>> MIME-Version: 1.0
>>>>> Content-Transfer-Encoding: quoted-printable
>>>>> Precedence: list
>>>>> Reply-To: Jerry Pittman <jerryp49 at worldnet.att.net>
>>>>> Message: 1
>>>>>
>>>>> Hello to all,
>>>>> HELP!  I wonder if anyone has run into this problem:
>>>>>
>>>>> My 101E was just idling along while I was working on the computer the
>>>>>       
>>>>
>> =
>>  
>>
>>>>> other evening, when I started smelling something hot.  I shot the rig
>>>>>       
>>>>
>> =
>>  
>>
>>>>> off immediately and found that the bias control (VR1) on the 
>>>>> voltage =
>>>>> control board (PB1547B) had over heated, as well as the (2) 10K =
>>>>> resistors on either side of the control.
>>>>>
>>>>> When I check the voltage at pin 5 of the 1547 board, I found that it
>>>>>       
>>>>
>> was
>>  
>>
>>> =
>>>   
>>>
>>>>> getting -160v instead of -100v.  I went to the Rectifier board
>>>>>       
>>>>
>> (PB1076B)
>>  
>>
>>> =
>>>   
>>>
>>>>> and made tests there.  When I disconnected the lead from the -100v =
>>>>> terminal, the voltage shows -60v but with it is connected it shows =
>>>>> -160v.  With the lead disconnected I also tested it for AC voltage 
>>>>> and
>>>>>       
>>>>
>> =
>>  
>>
>>>>> it shows 125vac as well as -60vdc.
>>>>>
>>>>> I checked all the components on the 1076B board and found all okay,
>>>>>       
>>>>
>> but
>>  
>>
>>> =
>>>   
>>>
>>>>> just to be sure I hadn't missed something, I put in a used PB1076B
>>>>>       
>>>>
>> board
>>  
>>
>>> =
>>>   
>>>
>>>>> and found all of the same readings.  I had already checked all of the
>>>>>       
>>>>
>> =
>>  
>>
>>>>> other voltages coming and going from the 1076B and all are correct =
>>>>> except the -100v.  The voltages from all of the transformer taps
>>>>>       
>>>>
>> appear
>>  
>>
>>> =
>>>   
>>>
>>>>> to be within range as well.
>>>>>
>>>>> Does anyone have an Idea or run into this before?
>>>>>
>>>>> Thanks in advance for any responses.
>>>>> Jerry
>>>>> WD4OIX
>>>>> jerryp49 at att.net------------------------------
>>>>>
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>>>>>
>>>>> End of Yaesu Digest, Vol 14, Issue 9
>>>>> ************************************
>>>>>
>>>>>       
>>>>
>>
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>>  
>>
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