Collins Radio 516F-2 Power Supply Blowing Fuse & Arcing Problem

Update - 4/22/2018 - Had the exact same thing happen again (11 months later) - arced right thru the insulation from one wire to the other, not to ground. The leads that arc are the ones going to pin 4 and 6 (the plates) of the 5R4. This time I replaced the wires (again) except I used meter lead wire with thick insulation. I also did not cinch down the cable ties so hard. For 800 VDC to the plates of the 6146's and the Collins PS being a full wave into a choke input filter, the RMS voltage, plate to plate, on the 5R4 will be approximately 1800 volts. This is twice I have had the arcing problem. I think it is best to make sure these two wires coming from the transformer to the 5R4 can withstand some serious high voltage. 10KV insulation would be a good idea. 73 WA4QGA
Hoping to help others save their original Collins power supply which will look like a shorted power transformer but actually is just arcing between wires within the power supply that is easily repaired.

[@bucyruserie1211]

David you have stated in prior videos that you like to see other people's work shops, equipment, etc..... Mr Carlson's Lab just posted a video of his 1940's Gates BC-250-GY Broadcast transmitter, I think you would enjoy watching if you have not done so already.. Take care, Tom

[@waynethompson8416]

Would love to see a short video where you give us an update where you let us know if you had anymore arcing issues.

[@ElPasoTubeAmps]

I am glad to see that this video may have helped you. I posted an update above that I will copy and paste here. Since this video I did, indeed, have more arcing problems until I completely eliminated the original external wires on the transformer HV secondary winding and replaced those wires with red meter lead wire. Since the second fix as described below, I have had no issues. Not sure if I mentioned it in this video but I had arcing problems on the 5R4 tube socket, pins 4 and 6 to ground (where the transformer HV windings connect to the plates of the 5R4) and that was solved by using old style red TV glyptal HV liquid insulation (know as Red GLPT, Mouser.com # 590-4228-225ML) around the top and side of the socket next to where the pins of the 5R4 plug into the socket. Update - 4/22/2018 - Had the exact same thing happen again (11 months later) - arced right thru the insulation from one wire to the other, not to ground. The leads that arc are the ones going to pin 4 and 6 (the plates) of the 5R4. This time I replaced the wires (again) except I used meter lead wire with thick insulation. I also did not cinch down the cable ties so hard. For 800 VDC to the plates of the 6146's and the Collins PS being a full wave into a choke input filter, the voltage, plate to plate, on the 5R4 will be approximately 1800 volts. This is twice I have had the arcing problem. I think it is best to make sure these two wires coming from the transformer to the 5R4 can withstand some serious high voltage. 10KV insulation would be a good idea. 73 WA4QGA Hoping to help others save their original Collins power supply which will look like a shorted power transformer but actually is just arcing between wires within the power supply that is easily repaired.

[@paullongoria5764]

Hookup wire is generally rated at 600 volts breakdown voltage. I don't know what Collins originally spec'd , but you can source wire from Belden or other mfgs to almost any voltage rating you need.

[@captlarry-3525]

AMEN.. SOME FIBERGLASS SPAGHETTI WILL FIX THIS.. ALONG WITH BETTER LEAD DRESS... SINCE IT IS IN CONTACT WITH A CAPACITOR LEAD AND ARCING AT THAT POINT !

[@abelezcurra4104]

Many, many thanks for this post! I had this same issue a few days ago and couldn't understand what happened and after seeing this video now I realize about the arcing (it happens twice on the 516F-2 PS that I was refurbishing) and blew two fuses. I'm going to get some High voltage cables! Thanks again.

[@ElPasoTubeAmps]

I am very pleased this helped. I have had no issues after replacing the two HV AC wires going to pins 4 and 6 on the 5R4 with HV meter lead wire. Pretty amazing how thin that insulation is in the original transformer. It appears after it dried out over 50-60 years, it became a little conductive. I think I also mentioned in this video that I had arcing at the 5R4 tube socket that I cured with red glyptal. That occured at the top of the socket of the 5R4 to the chassis. 73

[@abelezcurra4104]

@@ElPasoTubeAmps I have added insulation to those cables from the transformer and is working perfect. Thanks!!

[@ElPasoTubeAmps]

@@abelezcurra4104 Very good... I think the lesson here is 50-60 years of insulating drying out can be a problem but it can be fixed. I am also going to assume in some cases, this is diagnosed as a shorted transformer and is considered an unfix-able loss. I am very pleased that you took the time to diagnose the problem and resolve it. WA4QGA 73

[@militaryhfradio244]

David, I appreciate the video. We recently had West Point's (W2KGY) 32S-1 refurbished along with power supply. I left the supply on for almost a week and found it blew a fuse. I replaced tubes but still blew fuses. I heard about these things needing 110 instead 120. I am going to try your approach and see if it fixes it without needing to drop 120 to 110.

[@ElPasoTubeAmps]

Matthew, I hope it fixes your problem. I haven't had a single issue since this fix almost exactly one year ago of this posting. Some people put in SS rectifiers. I think that is a really bad idea. The one thing they sometimes also do that can possibly help if SS rectifiers are installed is add the now unused 5 volt rectifier windings in series with the primary (making sure phase is correct, etc) and that would help drop the secondary voltage but still probably best to stay with the 5U4 and 5R4. The 5R4 is necessary for the 800 volts as I have used a 5U4 in that socket and seen it arc inside the tube. I have had this PS since 1983 and it was used then. Also, every year or two, I sparingly and with TLC spray clean the band switches with the best contact cleaner I can find. Even so, sometimes I have to carefully "wiggle" the switch(s) into good contact if I haven't used the radio in a couple of weeks. Overall, it is still a grand radio transmitter and I am on it pretty much daily. Best of luck and keep the 32S-1 working. 73 WA4QGA

[@militaryhfradio244]

ElPaso TubeAmps , David it will be fun to try it out as I thought it might be something inside the 32S causing it. I had PS on and then plugged it to the 32S and fuse would blow...of course placing PS under load could cause that condition. Before all this started up, we visited ARRL HQs with our Cadets and Bob Allison himself tested our 32S and 75S. 60 to 80W output depending on band. Not bad for a radio that was used throughout 60s, 70s, and portion of 80s before just sitting on a shelf up until N2AAN refurbished them Dec of 2017. 73's KF4WZB

[@eliduttman315]

Dave, You did a VERY nice job. The PTFE insulated wire you put in should hold up better over time than the OEM PVC insulated stuff. PVC is pretty rigid and requires plasticizers to be flexible. I suspect those plasticizers failed over time. Definitely replace the selenium rectifier. Those things are ticking, toxic, time bombs. :>(( It's only a question of when, not if, failure will occur. When a selenium rectifier fails, toxic vapor and dust are produced. Some additional resistance is needed to account for the lower forward drop in silicon vs. selenium. Eli D.

[@ElPasoTubeAmps]

Eli, You are right, I should have replaced the bias rectifier while I had it out. Actually, it may not be selenium. It is an encapsulated unit so, hopefully, that will prevent the thing from going up in smoke and poisoning me. :-) That is good to know about the PVC insulate wire. I think I said it would be about 45 years old but if it was made in 1962, as I suspect, it is 55 years old. Still, I am a bit surprised I have had two incidences of arcing between these wires. One method to deal with replacing the 5U4 and 5R4 with SS rectifiers is to use those two rectifier filament winding in series with the primary giving an additional 10 volt primary option. However, I suspect with SS rectifiers, the amount of voltage drop derived from the additional primary turns would be lost in the voltage gain from the SS rectifiers and the HV would only get higher, I hear as much as 1 KV from some blogs. I like to keep this old stuff as original as possible and an additional 20 watts, or so, output is not what I am after. Thanks for your comments and information.

[@mikesamra9126]

David,I would put a 1N4007 diode across that selenium because if that negative bias voltage fails which it can,end up lunching the 6146s.

[@LarryTusoni]

Interesting - would you add it without disconnection the selenium? You need to at least removed one leg of the selenium rectifier.

[@TechTins_Projects]

55 years since 1962. Great video. Love your approach. What would have caused such arcing to occur?

[@ElPasoTubeAmps]

I just updated my comment as I had this arcing problem again, same place within the wires. It has happened at a place in the wiring where they (gently) make a 90 degree bend and the two HV wires out of the power transformer are routed to the tube socket of the 5R4. This time I replaced the arcing wires with some blue meter lead wire with seriously thick insulation.

[@knightsofnee8626]

@@ElPasoTubeAmps how has that worked out?

[@ElPasoTubeAmps]

@@knightsofnee8626 Haven't had any issues since this last repair.

[@matthewf1979]

Does that teflon insulation strip off easily? I bought some stuff from Tube Depot a while back and it's really stiff, hard to cut and damn near fireproof. I believe it's called Tefzel. I wouldn't recommend it for anyone working on stationary equipment, but it would probably be the absolute best for vehicle mounted or off grid boondocks can't ever fail operation. It's really thin insulation for 20awg 600v too. I would love to have old school cloth covered vinyl wire like the transformer from the late 50's/early 60's. I would pop the bells off every transformer in the newer amps I built immediately! The patterns of stripes and spirals are beautiful on that stuff.

[@ElPasoTubeAmps]

Hi Matt, This Teflon insulation wire that I have is great. It isn't hard to strip with a good sharp wire stripper and the wire inside is a silver plate which accepts solder better than anything I have ever used. It sounds like the Tefzel wire you have is very flexible. From another comment on this video, it seems the old wire that Collins used in the early 1960's was a PVC with a softening agent that, over time, deteriorates and starts to become somewhat conductive. I have some of the old style HV wire you are describing. I like it too and it is usually pretty big as #14 or #12. Works great for me and I use it at 3500 volts and more.

[@st2nh]

Great

[@gilbertstevenson3275]

well you know the Thunderbolt comes with a lockout switch in the back of it when you take the casing off I had had it wife 110 but when you turn the power on the 4-4 hundreds light up real nice and meet the fan comes on when you hit the high voltage switch with the safety lockout switch pushed in it blows a fuse I tried cleaning the prongs on the tubes will you trying to be Plus on act like a goes to ground and knock out a fuse on the the Thunderbolt amplifier

[@gilbertstevenson3275]

I have a Johnson Viking Thunderbolt desktop one of the 866 mercury vapor tube socket Arc over and the chassis and I wonder what caused that when you hit the high voltage switch on it it Blow the fuse underneath it has an oil capacitor on that amp it's a fuse right beside the high voltage caps do you think the Transformer might be bad I hope not

[@ElPasoTubeAmps]

It doesn't sound like a bad transformer since it is producing enough voltage to arc. Is the arc inside the 866A ? Maybe it is a bad tube ? I think I would pull the 866A's out and see if it arcs. Oil capacitors could be bad but they do last a very long time. BE CAREFUL. Always use a ground stick (dead-man stick to short all HV points to ground) This thing can kill.

[@johnsimms3957]

Would it help if the wires weren't so close together?

[@ElPasoTubeAmps]

i guess that would be best but for compact reasons they are usually twisted together with many other wires. For real HV connections, I use either HV meter lead wire or solid conductor spark plug wire. This is the first time I have ever had the issue of arcing between wire-to-wire and in this particular supply it has happened twice. When I research on the Internet this issue, it seems no one has had these problems. I don't know why my situation seems unique.

[@JesusvonNazaret]

Insulation aged and became brittle?

[@ElPasoTubeAmps]

That made sense to me at the time as the PS and wires are well over 50 years old but it happened again today with the new wire I put in eleven months ago so this time I replaced the arcing wires with meter test lead wire.