1854-0003 is a good part number. I have a few here that were removed
from equipment.
Possibly someone with the proper equipment could characterize this
part and determine a suitable parametric substitute.
73
Glenn
WB4UIV
At 11:43 AM 8/9/2009, you wrote:
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 <[email protected]>:
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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