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 Post subject: Johnson Viking II Issue
PostPosted: Nov Fri 13, 2020 3:10 am 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
Hello all, I’m having an issue with my Viking II, when I tune up on any band and go to check Plate current I hear HUM and then POP goes the fuse. I noted on the Plate switch that it shows constant continuity between the red and black wires only the green and white switch open close. The unit wired to it is just a 12v PTT so I don’t shock my butt, it works great!
I removed and tested the 6 domino capacitors on the Coupling switch as it was suggested to check as they are know to go bad but they tested good, all 6.
Any suggestions on what to try next would be greatly appreciated!

Thank you, Andrew

Oh ya pic of the Plate switch.
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E953C7C9-A33A-410F-80C1-3DAD70B9FAF1.png
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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Fri 13, 2020 3:21 am 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
Remove the 5R4 tubes and test the HV transformer for an internal short first. Next, remove the 6146 plate caps and test. Next, clip one lead of C46 .01uF capacitor at the 6146 RF choke HV input. Although very rare, the 8uF 1000 volt oil cap could be bad. Temporary install two series 22uF 450 volt or what ever you own electrolytic caps. Other issue may be the 5R4 rectifier tube filament winding is breaking down. Remove the 5 volt filament wires and solid-state the 5R4s. Due to the choke, use seven series 1000 volt diodes for each 5R4. Cheap 1N4007 are a good choice. You have to place the transmitter in transmit for the above tests.

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Last edited by jimbenedict on Nov Fri 13, 2020 4:38 am, edited 3 times in total.

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Fri 13, 2020 4:08 am 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
Thanks for the reply, I tested the oil cap and it’s shows 8.1uf on my meter. I will look into the rest tomorrow.

Thank you


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Fri 13, 2020 5:02 am 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
BTW- IMO the Johnson Viking 1 and II are the best AM transmitter ever made. Even the Collins 32V series have a lot of low B+ transformer failure and difficult to service. 110 lbs is too heavy too. Heathkit DX-100 is 100 lbs. Viking II is only 70lbs. I think the Viking I is about 90 lbs due to rack type case, but can be carried with transmitter separated from the case for about 65lbs and 25 lbs.

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 1:44 am 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
Update?

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 6:01 am 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
I checked the transformer and found no short. I pulled the 8uf oil filled Cap and it checks good. While I had the 8uf cap out I checked for continuity from the positive lead of the cap to ground and it shows a short. I did that with the 4 HV tubes removed. I’m not sure if the plate switch can cause an issue as the one side of the switch is always remaining closed so I did order a new switch.
I’m going to check the rest as you suggested hopefully tomorrow.


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 6:30 am 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
Ugctheaters wrote:
I checked the transformer and found no short. I pulled the 8uf oil filled Cap and it checks good. While I had the 8uf cap out I checked for continuity from the positive lead of the cap to ground and it shows a short. I did that with the 4 HV tubes removed. I’m not sure if the plate switch can cause an issue as the one side of the switch is always remaining closed so I did order a new switch.
I’m going to check the rest as you suggested hopefully tomorrow.

Positive on 8uF 1KV cap should show 20K ohm to ground. To be a zero ohm short to ground it would likely be a short thru the modulation transformer. Disconnect the modulation transformer wires and check for short again. Plate switch is not connected to the high voltage.

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 2:22 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
Ok will try disconnecting modulation xfmr today, thank you again!


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 3:42 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
disconnected audio transformer and still seeing shot to ground from 8uf oil cap. the audio transformer shows 420ohms across leads disconnected. here is a pic of one of the sections that i had rebuilt as it was missing most parts when i acquired this transmitter maybe i did something wrong?
also if you look at the terminal strip to the left i numbered them 1-5 and I'm seeing this on my meter from the 8uf oil filed cap disconnected and audio transformer disconnected.
1) short to ground
2) short to ground
3) short to ground
4) 95ohms
5) 105ohms
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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 6:09 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 22185
Location: Somers, CT
With the modulation transformer disconnected, put the mode switch in the AM position and see if the short still shows on the filter cap... if not, does the short show on the final tube plate to ground? If the short is on the plate, check for a bad plate bypass capacitor. If the radio was modified with a 1 mH or 2.5 mH choke from the antenna to ground, check for a bad plate coupling cap to the pi network.

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 6:33 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
With the modulation transformer disconnected and the switched to phone (I assume AM?) I still show a short


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 6:37 pm 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
Did you discinnect 5R4 filament windings and C46 capacitor?

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 7:33 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
I didnt :shock: I will do when I get home later, once again thank you!


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 10:08 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
OK I disconnect 5R4 filament windings and C46 capacitor and modulation transformer and still seeing a short to ground.


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 10:36 pm 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
Ugctheaters wrote:
OK I disconnect 5R4 filament windings and C46 capacitor and modulation transformer and still seeing a short to ground.

You must have a wiring error. It would be too difficult to see wiring in a picture. I suggest finding a Ham in your local area to find the short.

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 10:45 pm 
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Joined: Jun Sun 19, 2011 2:31 pm
Posts: 7694
Did you try what Pete asked you to do earlier in terms of the short being in the RF compartment? To check, temporarily disconnect the lead from SW3B that goes to L21/C46 which will isolate the HV section from the rest.

Rodger WQ9E


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Sat 14, 2020 11:18 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
Yes I tried all the suggestions and thank for the help, I do believe it to be a wiring issue. I just acquired a copy of the assembly instructions so I am going to follow some wires. I already found a one issue on the CW/ Phone switch in regards to 2 wires and the fuse one pin off. I’m guessing my best bet is to just take my time do it proper and trace each line back to stock and go from there.

Thanks again everyone I appreciate it


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Mon 16, 2020 9:41 pm 
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Joined: Mar Wed 27, 2019 1:56 am
Posts: 246
Location: Mountainside, NJ
OH MAN after all this I followed the assembly instructions, checked every component, connection bla bla bla and so on. I get to the time to test your work part and pop the fuse goes. It happened at the insert your 5R4GT tubes. pull ther tubes and check on my BK747 and they test good, check on my Precision 920 and I get a Filament short on both tubes. now is it normal to get both tubes with a filament short or did something cause this? So i go back and look and still that DANG short from 8uf cap to ground!


Last edited by Ugctheaters on Nov Mon 16, 2020 10:21 pm, edited 1 time in total.

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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Mon 16, 2020 9:49 pm 
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Joined: Jun Sun 19, 2011 2:31 pm
Posts: 7694
Those two wires are the high current filamentary heater winding from the LV transformer and will show a low resistance across those wires because the winding resistance is very low. They should NOT show a short to ground however.

There is no reason to apply power blowing out fuses and potentially damaging components while there is still an easily measured HV short.

If you haven't already done so, please disconnect the HV feed to the junction of C46/L21 and measure the resistance to ground from L21 after you have disconnected it.

Don't apply power again until you locate the failure point. It is hard on components and increases the possibility of you being injured by high voltage. The oil impregnated filter cap in the Viking II will hold a charge for a very long time if the bleeder resistor opens and those resistors do fail.

And on edit, take a very good look at the top and bottom of the 5R4 sockets which are prone to developing carbon tracks to ground. These won't result in a zero resistance reading but the resistance would be low and would definitely blow fuses.

At this point, isolate portions of the HV circuit to find where the short is located.

Rodger WQ9E


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 Post subject: Re: Johnson Viking II Issue
PostPosted: Nov Tue 17, 2020 12:00 am 
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Joined: Jan Tue 07, 2020 1:41 am
Posts: 3567
Location: Fenton, MI 48430
Ugctheaters wrote:
OH MAN after all this I followed the assembly instructions, checked every component, connection bla bla bla and so on. I get to the time to test your work part and pop the fuse goes. It happened at the insert your 5R4GT tubes. pull ther tubes and check on my BK747 and they test good, check on my Precision 920 and I get a Filament short on both tubes. now is it normal to get both tubes with a filament short or did something cause this? So i go back and look and still that DANG short from 8uf cap to ground!

I think your Precision 920 is in error. I would use a 250 watt light bulb in series with the 120 volts line in to stop the fuse blowing stress. No shorts produces a dim bulb. Short produces close to full brightness bulb. No shorts shows HV available.

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