[time-nuts] HP 106B part no.

[Brian Kirby]

Double check: "Q11 is marked as 1854-0003."  I can't find it in any of 
the HP cross references.

Brian - KD4FM


Jim Palfreyman wrote:
> Hi all,
>
> Latest update.
>
> With some help and phone calls from Bill the fault seems to have been
> isolated. I have removed Q11 from inside the oven and it is cactus. Q9
> is also very suspect so I'm going to replace that for good measure.
>
> Q9 is a 2N1701 in a T08 package. Thanks to various people I should be
> able to track one down. Q11 is marked as 1854-0003 and that's an HP
> internal number and all I know. Might have to substitute that one.
>
> After all this I have some quality photos and can knock up some good
> descriptions of the repairs and the 106B internals if anyone is
> interested. Any websites hanging around that want to take what I have?
>
> Regards and thanks to all!
>
> Jim Palfreyman
>
>
> 2009/8/9 Adrian <rfnuts at arcor.de>:
>   
>> Re-read Jim's posts.
>>
>> To me it seems clear that he is talking about the 2N1701 Q3 in the upper
>> right corner of fig. 5-12.
>> He mentioned that +18 measures high, around 26V.
>> So, the problem is NOT in the battery charger circuit.
>>
>> The purpose of that Q3 is to generate +17.4V (and +7V) from +26V, with the
>> base being connected to +18V, thus the emitter voltage of Q3 is +18V - 0.6
>> to - 0.7V.
>>
>> The +18V regulator circuit is on the lower left of fig 5-8, A1A4 Outer Oven
>> Controller. For a circuit description see 4-40 to 4-44.
>>
>> The +18V feed the AC amplifier (A1A2), the +15V through R14 (might be cooked
>> if run at 26V for extended time) and CR2 on the same board, the power
>> amplifier (A1A3), the outer oven temperature control circuit (decoupled
>> +18V), and the inner oven control cuircuit A1A5.
>> The 17.4V that are derived from +18V feed the dividers.
>>
>> Any adjustments make sense only after fixing the +18V supply.
>>
>> Actually, Q3 might as well be shorted. I would first remove it from the
>> circuit to see if the +18V are then correct.
>> If not, check the voltages at Q9 and Q7 of A1A4. Q9 is mounted on the oven
>> housing cover.
>>
>> Regards,
>> Adrian
>>
>> Bruce Griffiths schrieb:
>>     
>>> christopher hoover wrote:
>>>
>>>       
>>>>>  The 2N1701 is a general purpose transistor rated at 60V, 2.5A.
>>>>>
>>>>>           
>>>> I've mentioned this before, but it bears repeating.
>>>>
>>>> If you are having trouble with an old school linear power supply, in
>>>> many cases you can replace the TO-220 PNP pass transistor *and* the
>>>> reguatlor circuit (based on a 723 or whatever) with a modern
>>>> integrated regulator in TO-220 such as an LT1581.  Strip the regular
>>>> board of everything except for the the input and output caps (if they
>>>> are still good) and wire up a pair of resistors to set the voltage.  Add
>>>> a couple of jumpers to complete the circuit.   And then you are
>>>> good to go.
>>>>
>>>> -ch
>>>>
>>>>
>>>>         
>>> That probably wont work in this case.
>>> The supply is actually an NPN discrete darlington buffered 32V zener
>>> with a current limit transistor to set the battery charging current to
>>> one of 2 values.
>>> With the battery removed the supply output should rise to 32V - 2Vbe - a
>>> diode drop, ie about 29.8V or so.
>>> The series diode is required to isolate the battery from the regulator
>>> output when the main fails.
>>> It should be much quicker and easier to just find suitable transistors.
>>>
>>> Bruce
>>>
>>>
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>
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