Author Topic: B&K 2040 Repair video  (Read 21460 times)

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Offline Porkchop

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Re: B&K 2040 Repair video
« Reply #30 on: June 04, 2016, 06:53:14 PM »
I hate to bring up an old thread but since there's only a few, I guess it's ok, haha.

I've got one of these also, checking the output on two different frequency counters, I see 27.183 on channel 19.  Well actually on the BK 1801 counter, I see 27.184 and on my Victor VC2000, I see the 27.813 reading.  I opened up the crystal oven to adjust the trimmer as per the service manual... well, made no difference and it looked kinda bad.  On the side of it is 8-60, that's the only number or markings on the piece, I figure it means 8pf on the lowest adjustment and 60pf on the highest.  So I ordered something very close from Digikey, it arrived today and I put it in as best I could (not the same exactly as what came out).  So I get the same exact adjustment ranges or frequency, still off by the same readings.

Those two crystals that are inside, the 10.240 and 10.243 mhz.  On the 10.243 crystal, using the oscillator built into the frequency counter I get 10241.457 kHz which is two off from what's marked on the part.  Which is also two off just like the frequency output of the generator.  Could this be the issue?

The 10.240 piece, I get 10239.657 or so... which is almost dead on for what's marked on the part.  Other than being slightly off frequency, it seems to work just fine and I only noticed it once I hooked up an inline freq counter on my bench.  I attempted to find one with Google, seems they don't exist any more, so where would I find a crystal to replace the 10.243 one with?


Offline The Radio Shop

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Re: B&K 2040 Repair video
« Reply #31 on: June 05, 2016, 02:23:22 PM »
The 10.240 looks ok. The 10.243 is off quite a bit.  I am not sure if I have any more in stock but I will look.  This is not an off the shelf part.  But a custom cut crystal for these units.
I would contact ICM:
https://www.icmfg.com/
Let them know what you need and cut the crystal for you. They are about the best I know of.

You have to remember the age of this unit. And that oven plays a toll on parts. Check all the capacitors in that area to be sure some have not moved too far off. Should be a capacitor from crystal to ground off the 10.243.. If that cap goes out then the crystal will go off frequency.
Buddy kc4umo

Offline The Radio Shop

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Re: B&K 2040 Repair video
« Reply #32 on: June 05, 2016, 02:24:25 PM »
BTW
Welcome to the forum. Are you the PorkChop from CBT?
Buddy kc4umo

Offline Porkchop

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Re: B&K 2040 Repair video
« Reply #33 on: June 05, 2016, 04:45:16 PM »
That would be me! I found this site by luck looking for a solution, looks good and lots of cool stuff here!

I put it back together cause I needed some sort of generator to check a radio, it now shows 27.1849 on the 1801, haven't checked with the other counter yet. I did email that company though, guess I picked wisely huh?  I'm going to replace everything in that section, just got to order the parts.

I really like this generator and I have the whole setup including the scope for it but it's a POS. Looking for another scope, just don't know what I really should buy, guess it depends on what I can afford.

Offline The Radio Shop

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Re: B&K 2040 Repair video
« Reply #34 on: June 06, 2016, 07:09:33 AM »
Cool. Hope you will find stuff here you like and can use. Not a lot of activity here. It comes and goes. But I spend most of my time here.

Good thing about the generator is it is still usable. Although it is off a bit.  Let me know what you find from the email.
Sort of hard to suggest a scope. Not knowing just how in depth you want to go.  If you are looking at expanding your knowledge and getting deeper into electronics then a Rigol DS1054Z is a good all around 60 MHz 4 channel scope hackable to 100 MHz.  If you just want something to use with the gen then about anything you find should be ok. What model do you have now?
Buddy kc4umo

Offline Bigmic919

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Re: B&K 2040 Repair video
« Reply #35 on: June 06, 2016, 11:13:17 PM »
My 2040 as best I can tell is dead on the modulation side. When you turn it on the meter doesn't move and the green light comes on for a few seconds then turns off. The mod meter doesn't move when adjusted and it doesn't move with the af adjustment either but the lights will change from + to - on the af side. I haven't as yet hooked it to anything to see what I am getting but first assumption is I got problems.

Offline Porkchop

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Re: B&K 2040 Repair video
« Reply #36 on: June 07, 2016, 02:36:15 AM »
Ok, so I emailed them and the reply I got was that they needed the holder style and load capacitance in order to make one.  SO.. this is where my ignorance will shine through, I don't know what the holder style is, I saw it somewhere but don't remember what site I was on when I was comparing them.  And I have no idea about the load capacitance... how might one find that out?

The two scopes I have now are by BK Precision, a 1474 and a 1474B.  Both of which I think are trash, I believe it'll take way too much work to get them back up and running and I really want something much newer, like what you're talking about.  So I'm thinking about tossing these two relics in the trash. 

BigMic919, don't be afraid to pop the lid off and look around.  Start testing some points in it and see what you get, it's possible it's something simple and easy to fix unless you need the same part I need... haha.

Offline The Radio Shop

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Re: B&K 2040 Repair video
« Reply #37 on: June 07, 2016, 07:16:54 AM »
Porkchop
The holder is HC-18/U. I cannot remember the load capacitance. I do have it written down somewhere. One thing we have done in the past is send the old crystal in and they can figure it out.

Bigmic
In the video above the same chip handles that section. it is a quad op-amp. Maybe be bad or missing voltages.
I can get more detailed on all this by the weekend guys.
Buddy kc4umo

Offline Bigmic919

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Re: B&K 2040 Repair video
« Reply #38 on: June 07, 2016, 01:28:12 PM »
That is where I was going to start. All I have is a 20 mhz scope will that work to check it out?

Offline The Radio Shop

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Re: B&K 2040 Repair video
« Reply #39 on: June 07, 2016, 04:39:28 PM »
That will work,
Buddy kc4umo

Offline Bigmic919

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Re: B&K 2040 Repair video
« Reply #40 on: June 07, 2016, 11:34:40 PM »
I checked it out and have signal on the scope at the input but nothing at all on the out put. I also noticed it looks like IC1 has been changed out as well if that makes a difference. Where is the best place to get these parts?

Offline Porkchop

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Re: B&K 2040 Repair video
« Reply #41 on: June 12, 2016, 12:04:20 AM »
Well boys, it appears mine has taken itself a dump.  I turned it on a few minutes ago to check a radio... nothing.  Well, the yellow/amber light about meter function burned steady even though the switch wasn't flipped.  I checked the output with my frequency counter and basically got nothing.  Turning the modulation and power knobs, the meters increase but I'm not getting anything out.  I opened it back up and checked before the signal left that box in the back, nothing there either. 

I don't get it.  It was working fine.  I turned it off and it sat in here for a few days, now it won't work.  This really puts me in a bind, can't check this pile of radios I have without a generator... dang it BK...

SO I guess this means I'm gonna have to buy a new one or new to me. 

Offline scootter

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Re: B&K 2040 Repair video
« Reply #42 on: June 12, 2016, 01:51:16 PM »
 Ok got the time to check Q312 with the flat side facing to the left, top pin is 12.89v, middle pin 12.18, bottom pin 0. Q313 top pin 12.98v, middle pin 12.13v, bottom pin 0. the oven has melted the styrofoam cover just like in the other post.

Offline Porkchop

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Re: B&K 2040 Repair video
« Reply #43 on: June 18, 2016, 02:47:01 PM »
Tell me more about that scope you mentioned. I bought a Marconi 2018 to use until I can figure out the 2040. Of course, I'm gonna use the 2018 but I still like the 2040.

That 2018 also showed me that Victore freq counter was off ass well.

Offline The Radio Shop

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Re: B&K 2040 Repair video
« Reply #44 on: June 20, 2016, 05:26:04 AM »
Ok got the time to check Q312 with the flat side facing to the left, top pin is 12.89v, middle pin 12.18, bottom pin 0. Q313 top pin 12.98v, middle pin 12.13v, bottom pin 0. the oven has melted the styrofoam cover just like in the other post.

Those sound correct. I will verify just as soon as I can.
Real busy here this week. Those covers have melted on about every unit you see now.
Buddy kc4umo