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 Post subject: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 1:33 am 
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Location: Davis, CA
In the middle of conducting an alignment several days ago my E-200D stopped working. I know nothing about this device and am looking for advice or a contact of someone who works on these older signal generators so that I can get it repaired .

I have no output on any of the ranges.

The meter functions when the meter switch is in the %Mod position but does not function when in the Carrier position.

The pilot lamp is working.

Any suggestions will be appreciated.

Bob


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 4:01 am 
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Location: Albuquerque, NM 87123
I have worked on a few. Could be a power supply failure to the RF circuitry, or something open inside the RF cage or at the function switch.


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 6:24 am 
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Having worked on a few of the E-200D generators myself as well, I agree with Johnny.

My first tests would be of the power supply voltages. Based on what you're saying, I suspect you'll see the 10V output OK, but the 9V output will be low or missing. If so, the filter cap, C32 would be a prime suspect.

It would be pretty easy to isolate the 9V feed to the RF section to see if the problem is in the supply itself or if there's something on the RF board pulling it down.

I'm not sure what equipment or experience you have, but that unit is not too bad to work on.

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 7:04 am 
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Try this site. It has a lot of good info.

http://e200d.eqth.net/

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 6:14 pm 
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I would look at the output jack. I bought one a few years back at a hamfest for $10 cause it didn't work I had it fixed inside 10 min after I got home as the output jack had came loose and broke the wire connection.

Good luck getting it working, I really like mine.


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 7:57 pm 
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k8cca wrote:
I would look at the output jack. I bought one a few years back at a hamfest for $10 cause it didn't work I had it fixed inside 10 min after I got home as the output jack had came loose and broke the wire connection.

Good luck getting it working, I really like mine.


Just thinking out loud (always dangerous for me) but wouldn't the carrier meter still work if this were the problem?

Always interesting troubleshooting by remote.

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 8:32 pm 
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Location: Davis, CA
Thanks for the comments.

I found the points on the circuit board near C32 that were labeled 10v and 9v and measured voltages. They were 10.0v and 8.73v respectively. Is the 8.73v measurement considered too low? If it is too low I will replace C32. If it is ok I will need further guidance on where and what to check. I do have a circuit diagram so references to the diagam might help me locate check points.

I checked the output jack and it seems ok.

Thanks, Bob


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 9:09 pm 
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Location: Albuquerque, NM 87123
My advice is to take the cage off and poke around; there may be bad connections in there. I assume that all bands are dead.


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 10:36 pm 
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Again, I second Johnny's suggestion - not that it needs it - and would add that I'd suggest starting by checking the voltages around Q3, the rf output transistor on that board.

On one of the units I restored Q3 was shorted and exhibited the same symptoms you are seeing.

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Thu 04, 2018 11:23 pm 
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I am not familiar with transistors at all. Do I check the voltages between ground and each lead of the transistor?

Bob


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 12:11 am 
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Yes, but carefully! They're not nearly as forgiving as tubes if you short somethings out.

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 12:40 am 
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Here is an earlier thread--includes information on a particular transistor that typically goes bad

viewtopic.php?f=8&t=300518&p=2515216&hilit=200D#p2515216

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 12:55 am 
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Thanks Pix. I was sure I'd been down this road before but couldn't find the thread earlier this afternoon.

Actually, the referenced thread shows all three of us have been here before!

What I was wanting to find was the pictorial diagram of the Q3 area of the board for Bob's benefit to save him a bit of tracing.

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 1:11 am 
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I checked the voltages at Q3. I used the lettering on the circuit board to identify the B, C, and E leads. The voltage readings are followed in parenthesis by the printed values indicated on the circuit diagram.

B: 3.88 (2)
C: 8.08 (8.8)
E: 4.05 ((1.3)

Is this an indication of a bad Q3?

Bob


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 1:13 am 
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I don't know where that funny face came from but the circuit diagram value should be 8.8v.

Bob


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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 1:38 am 
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In the values from the schematic, you have base = 2, and emitter= 1.3. That is a normal difference (0.7 volts) for an NPN Silicon transistor. Your reading indicate that transistor is almost certainly bad.

But, before you remove it, is it the one that is reported to fail often?

If you don't have a transistor tester (part of many DMMs), I can tell you how to do it with a n ohmmeter

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 1:50 am 
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Sure looks like Q3 has been toasted again, like it did on you in June of 2016 (see thread Pix linked).

Time to pull it carefully and test it as you did before in the above-linked thread.

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 1:55 am 
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as who did before??

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 2:51 am 
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Bob.

Am I confused again? Didn't we 3 have this discussion in the thread you linked?

Aren't you still waiting on a kewpie doll to arrive!

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 Post subject: Re: B&K Precision E-200D signal generator not functioning
PostPosted: Jan Fri 05, 2018 3:47 am 
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I feel terrible guys. I forgot all about that previous thread that was referenced above. That thread was originated by me with the same problem as today. Old age is setting in. I will pull the transistor and check it as suggested. If it checks out bad what replacement should I be looking for? (Chuck was kind to furnish one the last time).

Bob


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