(newbie) needs help with viking ll

[KR4WI]

I need help with troubleshootin this viking ll. This is my first ll, I got it this past Sat, The fellow I got it from,  got it a couple weeks ago at a hamfest. I went thru manual couple times on tune up, turned on the filaments, then did manual adjustments, turned on plates, did tuning and when I went to tune the finals, sounded like bacon sizzling on stove, looked inside and the 5r4 tubes  looked like they were sparking inside on the tops of them. also, blowed the fuse.

So, where do you think I need to start from here, I destroyed the 5r4s, I put a fuse in and the filaments would not light up. I welcome any and all advice, remember I am new at all this. Thank You Very Much. Matthew KR4WI

[WV Hoopie]

Matthew,

Welcome to AM. I'm sure lots of Viking II owners will chime in. First: Get a schematic of that beast, if you didn't get one with the purchase, BAMA has one free for the download.

Second: Replace very electrolitic cap in that rig, my thoughts are the filter caps in the power supply are bad and took out the 5R4's. I'd go as far as even replacing all the paper caps. I've seen that sizzle before in a DX100, did the same thing as you. Turned on the power before checking out the rig.

Third check every componet, resistor, coil, choke, transformer, wiring, etc.

Then and only then try the power switch.

Check in often and let us know how the project is coming along.

73's
wd8kdg
Craig

[KB2WIG]

Matthew,
               I don't have a VK2 or the schematic so i'm not the one to advise you. There are a few things to consider/amplify. What type of test equipment do you have? Do you have the schematic for the unit? Do you have any experience working with high voltage? Any electronics training? Do you feel lucky? (sri Harry)..... Troubleshooting is a dynamic art, the most important part is Your personel safety........ As far as the bacon frying, we are hams and expect that to happen.......    gud luck     klc

[KR4WI]

Thanks for some quick response. Yes, I have schematic it came with tx. Test equipment I have old hickock meter, digital meter with ohms, cap, voltage on it, No I don't have any experience with this equpment, but I have been listening the last yr on the AM freqs, I do know this stuff has a lot of danger. I have been taking notes in a notepad while listening to qso's, and I read one tonite where someone said the 5v4 tube was known to go bad and take out the transformer. I guess we always think of the worse.
OK, well this is a good start. I will start checking those caps. Matthew KR4WI

[WQ9E]

Matthew,

I am not sure about sparking on top of the 5R4 tubes but I have had a problem in 2 rigs (including my Viking 1) with carbon tracks on the 5R4 sockets/ tube bases.  This is not uncommon in older rigs as dirt builds up and establishes a leakage path so I would start by pulling the tubes and checking the sockets and bases of the tubes for problems. 

Do you have any experience working around high voltage?  If so, consider measuring (AFTER removing all power from rig and using a shorting stick to short the high voltage supply) the resistance to ground for the HV supply, it should be about 20K.  If you have not worked around HV before, you really should find a local "elmer" who can assist you with repairing your Viking 2.  Please be extremely cautious if you are just becoming familiar with this type of gear as there are many ways to suffer accidents from unexpected voltage (open bleeder resistors leaving capacitors charged with high voltage, failed switches/relays, etc.)

 When you say you have no filaments, are you talking about all of the filaments or just those in the 5R4 tubes?  If you are using the standard Johnson plug that originally came with the Viking then you have fuses in both sides of the plug and you may have taken out both of them.  All filament voltage in the V2 are furnished by the "LV" transfomer T2 so if that transformer was damaged, you would probably lose all filaments (in addition to low voltage).

I have had a few "issues" over the years with both my Viking 1 and 2 so I will be happy to try to help with questions you have.  Feel free to email me (WQ9E@DTNSPEED.NET).
73, Rodger WQ9E

[KR4WI]

Rodger: Thank you, Sounds like some good simple points, First of all welcome to the forum. Sounds like you have had some experience with these old tx, I did check the tube socket/tube for carbon buildup, l cleaned them with alcohol, I do have an elmer about 30 miles up the road, I gave him a call and I will take it up on thursday for him to look at with me.
I really feel better with him helping since all this is new to me. but I really want to learn about how to troubleshoot this old stuff, The caps in the 5v4 have been changed, and i am not for sure, but one could be in backwards?? Then it may be for negative voltage, Thanks fo the email address, I may need to email you later on this project. Thanks Again Matthew KR4WI

[WA3VJB]

It's cool that you're diving into that VkgII and learning how to get it up and running.

You will find a tremendous amount of satisfaction having been around inside that rig leading up to when we finally get to work you on the air.

Plenty of folks on here to help, as you've already seen, and that deep bench can solve just about anything you can describe, including rounding up any parts/components from junkers if there's a calamity in there.

Paul/VJB

[WQ9E]

Matthew,

It sounds like you have a great plan for getting your Viking 2 "airworthy" again.  Have fun with the repair process, it is a great learning experience!  With equipment this old, things do happen but that is part of the interactive experience of using classic gear.  My Viking 1 came without a case but I was able to find an original case from the boatanchors mail list.  After taking care of a few circuit issues and putting it into its "new" case it was perfect for about 45 minutes then suddenly smoke everywhere!  The pilot lamp socket insulation had failed and shorted to ground which grounded the hot side of the 6.3 Volt circuit causing the insulation on the wire to begin burning/melting all the way back to the transformer.  I was in the room and shut it off before anything REALLY bad happened though I did have to remover the remains of that wire from the harness and fish a new one in (with an added filament fuse just so that particular failure mode doesn't happen again.)  That was 5 years ago and the Viking 1 hasn't missed a beat since so once you get yours going again it should give you many hours of trouble free on-the-air fun.

73, Rodger WQ9E

[Roy K8VWX]

       Matt I used to service TV and Radios years ago and before powering up any thing I would always measure  wirh a VOM/VTVM the resistance right at the rectifiers(B+ piont) to ground. It should be several thousands ohms with a slow rise as the fiter caps charged.The resistance will vary with the bleeder size and other voltage divider networks but should always show some fair size resistance.Then watch the rectifiers very close when you do power up and pull the plug quickly if they show any color.If they do start gettig red start disconnecting branch B+feeds until the culprit is found.Of course many other problems can arise but this is a good way to start. Good Luck - 73 Roy

[KR4WI]

Hello and thanks for help. I had chance to take it up to a friends house yesterday, I felt it was safer, and learned something too. We checked the power supply stage out and everything checked good, He checked the 5r4 tubes and they were weak, and they was a 5u4 where the 5v4 should had been.
Instead of ordering 5r4 and 5v4 he recommended I solid state it, Just put correct diodes in tube sockets. I tought I read somewhere here a while back about solid state instead of tube may raise the voltage to high on some rigs, what's your all thought on this? Matthew KR4WI

[WV Hoopie]

Matthew,

Pro's and Con's either way, I'd stick to the correct tube. They should not be hard to find. Someone living close to your QTH should have one of those cheaper than the internet sites, plus no expense of shipping or handling. (Support the local economy)

Anyone who has owned a Viking II could could chime in with reasons why solid state is better, maybe poor filimant transformers, etc. would dictate solid state is better.

With the power supply OK, check out the rest of the rig!!

73's
wd8kdg
Craig

[WA1GFZ]

I solid stated the power supplies in my V2 in 1983 and still works fine. Seems I remember the bias ended up needing a couple resistor changes to pull the voltage down a bit during tx.

[WQ9E]

If you are going to solid state your supply, you only need to "replace" one of the 5R4's since they are in parallel-of course pull the second tube out.  Use plenty of diodes in the 5R4 replacement strings as you don't want a small line transient to cause your solid state replacement to short.   I would still use a series resistor in the diode string for the replacements (especially for the 5V4) to keep voltage levels near original design value, this is very important if you are using the external VFO since its gas tube regulator circuit expects a certain voltage level from the Viking 2.  If you do solid state, disconnect the heater leads to the rectifiers so you will keep the HV off of the LV transformer, this is one of the only possible advantages in "solid stating" this transmitter.  I would also consider adding inrush current limiting (available from Mouser and DigiKey) to both the LV and Plate transformer primaries since your solid state replacements will have much lower series resistance.

Both my Viking 1 and 2 are using tube rectifiers and have all of their original iron.  I tend to stay with original rectifiers if there doesn't seem to be a real problem with using them.   I have replaced the 5U4G in a couple of Hallicrafters receivers I own just to take some of the heat load off of the power transformer, it does make this somewhat hot running transformer run much cooler.  My Desk KW came with commercial plug-in replacements for the 872A rectifiers so I left them in place.  I ended up removing the rectifier transformer from the unit which created a nice no holes mounting location for the solid state relays I used to replace a troublesome plate "contactor".

Good luck with whichever route you take!
Rodger WQ9E

[WA1GFZ]

I added an additional small filter choke on the Bias supply I think to change it to choke input. Do at least 5 KV PIV worth of diodes in the HV supply. I removed the two sockets for the bias and low voltage rectifiers. and put plates across the holes so I could mount terminal strips to hold diodes. The nice thing about the high voltage rectifiers is the tube sockets are further apart so bigger modulator tube will fit. I put a pair of 6DQ5 in as PDM modulators. I just repalced the tubes a few weeks ago and found they were still good so put them back in.

[KB2WIG]

M,
I suggest you get her working close to the original design specks. Take some measurements to give yourself a fall back position, and then you can play with modifications- there is a lot of material on this site. Don't try to do everything at one time, make some mods and see if they work...  This may save you from a lot of back tracking. << Is there a Chernobil resistor in the VFO in this rig??? >> gud luck .......   klc

[N8ECR]

Hi Matt:  There has been a lot of good suggestions for you hear,  As far as that sizzling sound, that was likly the rectifiers shorting out, and putting a load on the filament winding in the low voltage transformer...Not a good thing, It all starts from the fact that the electrolyic cap in the low voltage supply are just old and dried out and should have been replaced first.  I have heard of many VKII's that have lost there low voltage transformer, and actually have own one in the past.  Rule of thumb here is remove all tubes except the rectifiers, and hook the set up to a variac right from the start, and turn on all the switches, and slowly advance the variac over a period of a few hours.. always occationlly feeling the transformers and chokes for heating, any signs of heating you should stop and unplug the thing and look things over... But in the end I bet you are going to have to replace them elctrolytics, hopefully at this point it is not to late for the low voltage transformer. good luck...N8ECR!!!

[KR4WI]

Hello, And Thanks:  I would like to post that I got the viking ll going today. I found some resistors and a capacitor that was bad. This was my first fix so,I must say Thank you to Craig, KLC, Rodger, Paul, Roy,GFZ, and Mike I used  suggestions from all of you, and my Elmer that lives up the road, wb4nzs It is great help to have  AM forum with all the knowledgable folks that take the time to post to us new comers to the AM mode.  Thank You All.now I will be transmitting in the Angel Music Mode. Matthew KR4WI