AirKing 4602

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Re: AirKing 4602

Post by frank1956 on Tue Feb 09, 2016 8:19 am

willy,
Thanks for the clarification. I took the reading withe meter set at 200 ohms.

12SK7 pin 4 to wire connected to the lug on the antenna 00.3 ohms.
Red wire connected to the antenna via the terminal lug 00.3 ohms.
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Re: AirKing 4602

Post by Wildcat445 on Tue Feb 09, 2016 11:44 am

The red wire from the antenna to the terminal lug on the chassis appears to be going to the AVC bus. The other wire from that terminal lug goes to an IF can. The green wire from the antenna goes to the tuning cap, then down to pin 4 of the 12SK7. The resistor that Willy has pointed to looks like a resistor in the AVC line to me. You guys are getting close.......

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Re: AirKing 4602

Post by willy3486 on Tue Feb 09, 2016 12:49 pm

frank1956 wrote:
75X11 wrote:





Ok my next suggestion. Look in the photo  of the schematic I enclosed. I have drawn around a coil you want to check. It looks to have 3 lugs on it from the diagram. All three of the wires should connect. With that in mind you should get a reading on each check, check pin 1 to 2, 1 to 3, and 2 to 3. As with the other coil no resistance will mean a hair thin wire is broke. I think it is the coil from the post I quoted that is a cardboard form on the right hand side. Sometimes these coils can  have a wire broke.


Other thing I would check is the tuning cap itself  and the mounts. Sometimes the makers would use rubber bushings and they will dry out and ground to the chassis. If that is the case take out the screws and put new bushings in. I have used all kinds of stuff for bushings, rubber grommets,sink washers,etc , whatever works. If these are not the issue I would start at the antenna and check each component from there to the IF transfomers.  There is not a lot usually that goes wrong in this area but when it does it can be a pain as you have seen.

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Re: AirKing 4602

Post by 75X11 on Tue Feb 09, 2016 2:10 pm

Here is one replacement for the insulating grommets.

http://www.tuberadioforum.com/t2101-mounting-grommets
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Re: AirKing 4602

Post by frank1956 on Wed Feb 10, 2016 3:32 pm

willy,
In the attached picture is this the coil you are talking about the one I circled?? If so it has 3 three lug, but only two are connected. One goes to pin 6 12SA7 and the other to pin 5 via a mica via a wire to the tuning cap. I checked the mounts for the tuning cap and they are seem to be in good shape, not brittle or cracking.


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Re: AirKing 4602

Post by willy3486 on Wed Feb 10, 2016 4:29 pm

There should be three lugs connected. That is the coil on the diagram just under the tube you mentioned. What I think is going on the third lug is probably connected to the metal bracket piece that holds it to the chassis. these things can be decieving so here is what I would do. From the diagram it looks main electrolitic caps have the negative side  grounded, is this to the metal chassis? If so Check the ground of the caps and see if you find a direct connection with your ohmmeter to the lug of the coil that goes to the chassis. if yes this is the ground of that coil. Then connect one lead to the cap ground since it is a direct contact to the coil log then test the two lugs that you mentioned that go to the mica and the other connection. Do you get a reading? You should get a reading from the cap ground to each of the two lugs. If not that is the issue to the radio. If no connection inspect the coil and see if there is a wire broke. You can also lightly run a soldiering iron over the wax to melt it.

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Re: AirKing 4602

Post by frank1956 on Wed Feb 10, 2016 5:56 pm

willy,
There is a very thin piece of copper wire connected to the coil grounded to the chassis. The reading are below.

Electrolytic cap neg side to mica 6.6 ohms
Electrolytic cap neg side to 12SA7 pin 6 1.1 ohms
Electrolytic cap neg side to coil ground 00.4 ohms
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Re: AirKing 4602

Post by willy3486 on Wed Feb 10, 2016 8:17 pm

At this point without seeing I don't know what to suggest next.These are the steps I take with one not tuning. If you can inject the 455 signal into the circuit and it works from the IF down then it is in the tuning section. It sounds like the coils are fine. The one you checked and the antenna round coil. If the bushings are not letting it ground. Then if all parts replaced are checked for proper ratings and connection location. Then all the rest of the parts like resistors are checked and the tubes are good. I am stumped at this point without actually seeing the radio. Does anyone have any other suggestions?

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Re: AirKing 4602

Post by 75X11 on Wed Feb 10, 2016 8:51 pm

The only thing I can think of would be if the unit were misaligned somehow. It seems everything of fixed value is correct.
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Re: AirKing 4602

Post by Wildcat445 on Wed Feb 10, 2016 9:28 pm

We went thru an IF alignment earlier. Aligning the RF and oscillator trimmers on the tuning cap has not been done. Are you guys satisfied that the antenna is not the problem?

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Re: AirKing 4602

Post by willy3486 on Wed Feb 10, 2016 9:44 pm

At this point I can't think anything in the Antenna area being the problem. Has the IF freqency been injected in the IF transformers area? If not that could be done and rule out that area.

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Re: AirKing 4602

Post by Wildcat445 on Wed Feb 10, 2016 10:43 pm

We injected IF into the 2nd IF first, then the 1st IF, then where the antenna connected to the tuning cap.  We verified that the oscillator was running, both by seeing negative voltage on the grid of the converter tube, and by hearing the oscillator squeal in another radio.  We are getting IF all the way thru the radio.  For some reason, we are not getting RF.  IT is either not there, or is not getting past the tuning cap.  This does not make sense.  That radio should work.  I remember reading where you guys were working with the antenna, measuring resistance and that.  I'm like you guys.  I'm not aware of anything we have missed, and can't think of what should be next.....

Are we absolutely 100% satisfied that this radio is wired right? The schematic is horrible, and there are two or three versions of this chassis on the schematic. Could their be running production changes of which we are unaware? Has the wiring been confirmed as correct, beyond any reasonable doubt?

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Re: AirKing 4602

Post by willy3486 on Wed Feb 10, 2016 10:58 pm

Wildcat445 wrote:
Are we absolutely 100% satisfied that this radio is wired right?  The schematic is horrible, and there are two or three versions of this chassis on the schematic.  Could their be running production changes of which we are unaware?  Has the wiring been confirmed as correct, beyond any reasonable doubt?


Although its a pain one suggestion would be to follow each piece from the antenna down to the IF transformers and on. Two of the radios I have done did not go with diagrams. The philco had a magnet coil but the diagram was for a PM speaker. The Silvertone was suppose to be like a traveler I think it was but the area I was having trouble with was wrong in the beitmanss. Only after looking on some other info did I find the correct schematic in the riders. I would go down it by the schematic and also check each component.

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Re: AirKing 4602

Post by Wildcat445 on Thu Feb 11, 2016 1:00 am

Had this radio been messed with before Frank got it? Is there another schematic other than Riders for this radio? Perhaps a better one? We have to be overlooking something simple.

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Re: AirKing 4602

Post by frank1956 on Thu Feb 11, 2016 10:12 am

Wildcat445 wrote:Had this radio been messed with before Frank got it?  Is there another schematic other than Riders for this radio?  Perhaps a better one?  We have to be overlooking something simple.


WC,
To the best of my knowledge the radio was not messed with before I got it. I do agree that the schematic is terrible to work with, and with that said, since you and the rest do not have the radio right in front of you I am going to put this out. Going from what I can make out on the schematic and using the 12SK7 (closest to the antenna) & 12SA7 tubes  for an example these are my thoughts comparing the schematics with the radio. Not sure if this amounts to anything, but my two cents. Y"all are the experts. Side note someone wrote in pencil inside the radio S3 reversed???

Schematic  Tube 12SK7          
Pin 1 connected- not connected on radio                    
Pin 2  not connected-connected on radio
Pin 3 connected- connected on radio
pin 4 connected- connected on radio
pin 5 connected- connected on radio
pin 6 connected- connected on radio
pin 7 not connected- connected on radio
pin 8 connected- connected on radio

12SA7
pin 1 connected- not connected on radio
pin 2 connected- connected on radio
pin 3 connected- connected on radio
pin 4 connected- connected on radio
pin 5 connected- connected on radio
pin 6 connected- connected on radio
pin 7 not connected- connected to pin 2 12SK7
pin 8 connected- connected on radio
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Re: AirKing 4602

Post by Wildcat445 on Thu Feb 11, 2016 11:46 am

Pins 2 and 7 on the 12SK7 are to the filaments. Those should be connected to the rest of the tube filaments in series. Without those pins connected, that tube is not working. I remember you measuring elements on that tube, and you had B+. The radio will not work if that tube is dead. Pin 1 on metal tubes is typically connected to chassis. Pin 1 on metal tubes serves as a ground for the metal case used as a shield.

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Re: AirKing 4602

Post by frank1956 on Thu Feb 11, 2016 3:43 pm

So the schematic does not always agree with the radio? I am confused if the schematic show one thing and the radio another is this normal??
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Re: AirKing 4602

Post by willy3486 on Thu Feb 11, 2016 4:06 pm

frank1956 wrote:So the schematic does not always agree with the radio? I am confused if the schematic show one thing and the radio another is this normal??
 

Not necessary normal but it does happen.Sometimes they will leave out the wiring to the filiments because they go to a specific connection. That is so there will be less lines on the diagram. Different wiring can be production changes, previous repairmen changing stuff.  I see it from time to time. I fixed about 10 in the last month and 1 of them was not by the plans.   Another one yesterday had previous work done to add a speaker to a speaker with a coil magnet, it had a external speaker connection along with some weird stuff added and changed on the wiring of the antenna. Do you have any radio meets in your area? Do you know anyone else that works on them close? The reason is another set of eyes looking at it can give you a break. I have asked other people questions on stuff I was repairing as a person can sometimes get stumped. I am like wildcat I think there is something simple everyone is overlooking and I don't know what it could be. The IF sends out to the speaker so that section sounds like it works. So it has to be from the ant to the if . We checked the coils, the tuning cap rubber grommets holding it are ok. No obvious issues, all resistors ohmed out close or correct. All caps double checked to see if correct value and location.  I have had sets like this I have set aside then come back to and figure it out. I am thinking you have injected signals into the IF transformers but I don't remember if you injected a signal at the antenna and then follow it through to the IF transformers?

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Re: AirKing 4602

Post by Wildcat445 on Fri Feb 12, 2016 10:25 am

Frank got a 400 cycle tone modulated at 455 kHz thru from the antenna connection on the tuner to the speaker. This radio should be working. There is no part in it that we have not checked at least a dozen times. I don't remember seeing a picture of the entire bottom of the chassis. How about if we ask Frank to post a picture of the bottom and top of the chassis, along with the schematic on the same post. This will allow everybody who wants to a peek at what we are dealing with. I believe I'll print a copy of the schematic and blow it up so I can see better. There has to be a "got ya" somewhere on this radio. I don't know what else to do. Frank, if you decide to do this, get as detailed and clear a picture of the bottom and top of the chassis as you can. I don't know what else to do at this point.

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Re: AirKing 4602

Post by frank1956 on Fri Feb 12, 2016 12:30 pm

All I really appreciate your help on this. I was hoping for and easy fix for my brother-in-law affraid To answer willy question, there is no radio meets in my area that I am aware of, I do know of a place I can take it to, but was trying to avoid the $69.00 whats wrong with it fee lol. But per your request WC here are the pic's of top and bottom. Thanks again







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Re: AirKing 4602

Post by Wildcat445 on Fri Feb 12, 2016 1:25 pm

The only thing I have seen right off hand is this. Do you see the red wire going from the antenna to a terminal lug? That goes to the AVC bus. There is a white wire off that terminal, goes thru a piece of un-shrunken shrink tubing, then turns into a yellow wire that goes to the IF can. What is up with that wire? What's up with the un-shrunken shrink tubing? Is the yellow/white wire connected under that tubing?

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Re: AirKing 4602

Post by frank1956 on Fri Feb 12, 2016 2:17 pm

WC,
It is connected. Looks like someone for some reason cut the yellow wire and used a leftover piece of white wire to re-connect. But they are solder together for a connection.
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Re: AirKing 4602

Post by Wildcat445 on Fri Feb 12, 2016 2:35 pm

Got it, Frank. I'll keep looking.

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Re: AirKing 4602

Post by willy3486 on Sat Feb 13, 2016 12:44 am

I have one question about the radio and I am grasping at straws here but everything should work. I figure you have tested the tubes and they tested good but have you tried different tubes? On rare occasions I have had a tube that tested good but for whatever reason it was garbage. I ran across one this week like this. I would turn the radio on and it would work at first then nothing. I thought it was a wiring issue but could see nothing. Then I swapped it out with another one and its worked fine every since. I don't know why it did that but the tube tested good but was flakey. If you have other tubes have you tried them?

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Re: AirKing 4602

Post by frank1956 on Sat Feb 13, 2016 9:52 am

willy,
I have tried different tubes. I checked the ones that were already in the radio and then I obtained some NOS tubes and swap them out.

Just a question I was sitting here trying different things with this radio with no luck, so I decided to try tuning the oscillator. Turned on my signal generator per the schematic and let it warm up for about 30 mins or so, then turn on the radio and laid the leads across the radio I could not get any signal, tone or anything to come through the speakers. I wanted to make sure nothing was wrong with the signal generator and tried in on a working radio and it was fine. Is this something of interested Question Question
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Re: AirKing 4602

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