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b&k FUNCTION GENERATOR

chucksue

Jan 31, 2013
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I need help troubleshooting a b&k 3011b generator.The readout shows frequency change but there is no output at the b and c connector.There are two transistors just before the output and they are heat sinked and they are very hot.
 

shrtrnd

Jan 15, 2010
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Sounds like you've got an output problem, but the generator itself is still working.
I'd find a manual (schematic) for it if I could.
I think you mean a 'BNC' connector for the output.
Your transistors are heat sinked, so they're supposed to get hot. They may be bad, but
something in front of them made them get that hot if you've got no output.
A schematic should help you a lot in isolating the problem.
 

chucksue

Jan 31, 2013
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3011b

I found a schematic on line and bought it.The two transistors that get hot are the last ones before the output.In the circuit with the transistors are two electrolytic caps..They may be bad I haven't checked them yet.The transistors are set up like a push pull or a balanced circuit.
 

davenn

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Sep 5, 2009
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can you scan around that section of the circuit and post it ?

it may be easier to help you if we can see how its layed out

Dave
 

chucksue

Jan 31, 2013
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3011b schematic
Dave how do you post the schematic?I scanned it and have it in my doc's.I clicked on insert a image if that is where it is done.It asked for a htpl or something like that. ???????????
 

chucksue

Jan 31, 2013
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3011b

Here is the b and k schematic.

attachment.php


Please let me know if you are not able to view it.
 

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chucksue

Jan 31, 2013
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Jan 31, 2013
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3011B

The base to emitter voltages on the Q502 Q501 Q504 Q505 transistors all are around .7 volts.The Q503 has 2.84 volts base to emitter.
I replaced the 2n2905 transistor and it got hot also.I cut the base lead on this transistor and it didn't get hot.The base must be over biased.The signal atVR502 has all wave forms on it when I select the sine,square and saw tooth wave form.I do not see any out put on the collector of Q501.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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I'd check F501 (just in case)

And 2.84 V between base and emitter on Q503 seems very wrong. Just check again that you haven't measured base and collector. (It should be the same voltage as is across R502)

A failed Q503 *might* be affecting the signal at the collector of Q501. Remove Q503 (at least the base connection) and see if the signal reappears (at the collector of Q501).
 

chucksue

Jan 31, 2013
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3011 B

I had to remove the Q503.They have all the transistors soldered down close to the board.I still do not have any signal at the collector but a lot of static.I will order transistors to replace the 503.We will see what happens then.The base to emitter voltage I checked and it was high.Looking at the transistor the base and emitter should be the outside leads.I down loaded the data sheets to be sure.
 
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