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Author Topic: Titan 425 Help (Blowing Fuses)  (Read 14647 times)
W8JX
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Posts: 5798




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« Reply #75 on: February 10, 2013, 08:22:09 PM »

It has been my experience that a good rewinder often yields a better job than original. 

Plus you know its fresh and has not maybe been on a shelf or warehouse 5 or 10 years or even more.
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KE3WD
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Posts: 5689




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« Reply #76 on: February 11, 2013, 07:42:40 AM »

Well, I know a fellow who rebuilds motors and xfrmrs, a rewinder, if you will, and he tells me that he can incorporate newer technology stuff onto an older technology core.  Things like better compounds than varnish or shellac, synthetics that won't be deteriorated by bacteria or chemical action over time, use of wiring that has better insulative properties than the plain old "varnish" coated stuff, etc. 

I don't know the particulars, but I do know that the xformers, motors, alternators, etc. that he rebuilds often actually do run "better than when new".  Cooler, sometimes he can even up the power ante a bit at the same time, things like that. 


73
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WU2M
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« Reply #77 on: February 11, 2013, 10:23:36 AM »

Hello Everyone,
 I wanted to bring you all up to date. I have ordered a transformer from Ameritron which Lou is going to retrofit for me. Initially I was concerned because I like to play around with some digital modes. One of the things I enjoy from time to time is SSTV and I was concerned that I may have a problem sending images. Lou gave me some specs on what the transformer would do and it would work just fine. The AL 800H is rated at 1000 watts RTTY for 1/2 hour and I won't hit those kind of numbers. The modes I use are anywhere frome 1.5 to 4 minutes long so I see no problem going this route. I tend to run my amps on the easy side so I think this will work out just fine.
 I will update everyone soon.

Rocco
WU2M
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K4RVN
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Posts: 772




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« Reply #78 on: February 11, 2013, 11:32:40 AM »

I think you made a good decision Rocco and thanks for getting back as I have been following the thread with interest. Since the transformer suggested by Lou is in stock along with another small transformer, you should be troble free for years. I thought the price I found from Ameritron's site seemed reasonable. Good luck and enjoy your amp when Lou finishes with it.

Frank
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WU2M
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Posts: 29




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« Reply #79 on: February 11, 2013, 01:05:56 PM »

I have no doubt that when I get the amp back from Lou, it will be better then it was when it left TenTec brand new! Lou went through and tested the RF deck and gave it a clean bill of health.
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W1QJ
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Posts: 1446




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« Reply #80 on: February 11, 2013, 04:19:26 PM »

For all following this, like Rocco said we'll be using an Ameritron Al-800H treansformer for his 425.  The Al-800H runs a pair of 3cx800's just like the 425 and so the Ameritron transformer already has the correct high voltage and filament voltage. We will need another small transformer for the signal voltage of 20vac and the rectifier is already on the TenTec PC board for that.  The Ameritron transformer has a heat sensor built into the transformer which if it overheats will break the keying line until the transformer cools down.  I'll probably hook that sensor up to a indicator that will alert Rocco if the transformer get hot and the sensor engages. I have already moved the step start resistor and fuse off the PC board.  I put in a fuse holder so the step start fuse can be replacxed externally.  This should be an interesting project doing the retrofit.  I have an Al-800H myuself as well as the 425 and they both make about the same amount of output power.  The Ameritron transformer runs about 200 or so more volts on the plates.  This should lower the grid current at higher power.  When this project is completed I will report back, in the meantime I will rip the transformer out of there and get ready for the transplant. Hmmmm, transplant.  Lou
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W1NK
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« Reply #81 on: February 12, 2013, 09:01:46 AM »

Thanks for keeping us up to date Lou. I never fail to learn something from your  posts & emails.

 Frank, W1NK
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W1QJ
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Posts: 1446




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« Reply #82 on: February 12, 2013, 04:06:53 PM »

Thanks for keeping us up to date Lou. I never fail to learn something from your  posts & emails.

 Frank, W1NK

Hi Frank, How is your AL-811 running?  You ought to stop by when I am finished retrofitting the Ameritron transformer into the Ten Tec power supply.  I started planning for this project and I realized that I am going to have to rewire the rectifier board in the TT because the Ameritron transformer requires a doubler circuit.  The TT uses a FWB so I am going to have to change things around.  No big deal, just a bit more work.  This is like doing a transplant.  I ought to know Grin  Lou
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KE2TR
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« Reply #83 on: February 16, 2013, 05:52:42 AM »

I find this post interesting, using the AL800H xfmr is n excellent idea nd by the look of thing's TT wants to get outa the amp biz as well, maybe SS amp's might be there new way but Ameritron seem to kick there but in sale plus have many amp's on the table, maybe not the best amp's on the market but dm good value nd they seem to run and run for year's. W1QJ's xfmr swap is and excellent idea aand will keep that amp running for many year's to come, great job!
Jim
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W1QJ
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Posts: 1446




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« Reply #84 on: February 22, 2013, 09:03:21 PM »

I suppose all those who had been watching this thread are wondering whatever became of poor Rocco's sick power supply.  Rocco had it packed up and ready to go to Tenn. back to Ten Tec.  I figured if it was something simple like a bad cap or a diode or some such simple thing, it would be easier and cheaper to ship it to me in Connecticut when Rocco is in upstate New York.  Well he did send it to me and I was doing the troubleshooting and found the same thing Rocco found, it was blowing the step start fuse right away.  Soon as you turn the amp on BAM.  A common occurrance in older power supplies is usually a shorted diode or a bad filter cap.  So I had to get down in there and check the diodes.  I did find 3 shorted diodes in one leg of the 4 in the FWB.  I replaced all 4 didoes in that leg.  I thought I had this problem put to bed.  After that I tried it once again, and again BAM!  The step start fuse blew again.  I had a full set of replacement type electrolytic caps, so I quickly removed all 8 and put in 8 new ones.  They are the screw in type so they are easy to change. tried it again.  BAM!  Well at this point I know it's not the power supply that is the problem, meaning the diodes and the caps.  The next thing I suspected was the transformer so I disconnected the secondary of the transformer from the recitifier and I ran just the transformer alone.  NO problem now.  The transformer secondary AC voltages right right on the money and there was no fireworks or humming or anything.  So I assumed the transformer was OK.  Back to the schematic again. Mulling it over I noticed they have a HI/LO relay on the PC board which switches the HV secondary between a 1010v winding and a 550v winding that are in series.  The common of the relay goes to the rectifier and the joined winding CT (if you will) goes to the relay NO and the bottom of the 550v winding goes to the NC contact on the relay.  This way there is a selection of HV of about 1800v and on hi 2400v.  When I looked at the relay being used for switching of HV AC like that I saw it was only rated at 250vac  I figured that perhaps somehow there might be carbon  traces inside that small relay that was arcing over the windings.  So I tried bypassing the relay and wiring the HV secondary seperate from the relay and straight to the rectifier.  I thought this is the last resort.  BAM!  same thing happened again.  So I finally figured it was time to see if I can bring this power supply up slowly on my Variac to see if I can hear some groaning or start to see some smoke from someplace by bypassing the fuses.  So I got my trusty Variac which I bought years ago from someone who pulled out the grounding pin on the plug, and began to see what I can find out by ramping the line voltage up slowly, bypassing the fuses.  So I went into the power supply and picked up the mains to the PC board and ran it to a cheater cord and hot wired the PS for testing.  I also hooked up my HV meter to the HV ouput so I could monitor the HV to see what is going on.  SO I plugged in my Variac and the amp cheater cord to the Variac and I slowly ramped up the HV.  It ramped up just fine no problem, all the way up to 1500v.  This was my 120v Variac, so I thought I would get my big 240v Variac and go all the way with it.  So I get my 240v Variac and plug that in to the wall and then the cheater cord into the Variac plug.  The Variac was on zero volts and looking at the HV meter I had hooked up I can see about 150vdc coming out.   So I'm thinking where is that voltage coming from to give me that little bit of HV on the meter.  I pull the plug out of the Variac and the HV droped to zero.  That's not good.  The other variac didn't show that voltage coming out on the high side.  This Variac has a good plug on it with a ground.  Ok, so I start ramping up the voltage with this Variac.  The transformer starts groaning.  It's not liking something. SO I unplugged the secondary of the transformer to the rectifier and the transformer ramps up fine with no rectifier in line.  Wait a minute the power supply looked OK with my other Variac(no ground on the plug) with this Variac (with ground on the plug) the transformer groans badly trying to make high voltage, remove the recitifier from the secondary and the transformer is OK by itself.  Ok now, I know everything was OK when I had no ground attached to the Variac, HV came up no problem up to 1500vdc.  Switch to the other Variac with a ground plug and GROAN right away.  Remove rectifier from tansformer Ok by itlsef.  AH OH...  I think we have something fishy with this transformer.  My Ten Tec 425 power supply was across the room in a box.  I pulled it out hooked it up to my big Variac and it ramped up to 2500vdc with no problem.  So now I start taking some continuity readings on the transformer and I see eveything looks ok on the primary and the secondary, but wait, I have some continuity between the primary and seconday.  Thats not good.  Ran the same test on my 425 transformer and no continuity at all between the primary and secondary.  So looks like we got a bad transformer here. YUP!  Somehow whatever kind of short there is in the transformer it involves ground somehow. I have heard of many old timers that used choke input filters on power supplies that blew out to ground.  They would mount the choke on rubber or something to insulate it from ground and put it back in business.  I'm not doing that!  SO I emailed Rocco and I gave him the bad news that the problem with his power supply is weirdly shorted transformer.  Told him we need another transformer.  Giving it some thought I recalled that my Ameritron Al-800H runs a pair of 3CX800's and is bascially the same kind of amp as the Ten tec 425.  I figured why couldn't I transplant a transformer for an Al-800H into this unit?  I looked at my transformer in my 800H and I see it can fit perfectly sideways.  Only thing it didn't have was a 20vac winding for the 28vdc needed for the control voltage on the Ten Tec.  So I found I coulod use a small 3A 20vac transformer for that and there was plenty of room to mount it.  I looked up the price of the AL-800H transformer and the Ameritron website said $247.00.  I figured that wasn't a bad price and asked Rocco to check it out.  I told him I thought out the whole plan to transplant the 800H transformer and the little transformer for control voltage.  I said I think I can make this work.  The major consideration was that the 800H transformer requires a doubler circuit rectifier.  The present PC board in the Ten Ten is wired for a FWB.  I told Rocco I would get out my Dremel tool (can't live without it) and I would go in there and cut the traces off the PC board that configures the 4 diode legs into a FWB.  I would then do a point to point wiring of the 4 legs into a doubler circuit and tap it acordingly with the new transformer.  I then modified the capacitor PC board for doubler service by drilling a hole in the trace that connects caps 4 and 5 and connect my other AC secondary in that hole and solder it to that mid point on the cap board.  I unsoldered the molex plug from the PC board and marked each hole on the underside of the PC board with what wires need to be put back in there.  So when I had possesion of all the parts I mounted the both transformers in their places and then began sorting out the wiring that neded to be soldered into the PC board.  One by one I solder each wire in the right hole on the PC board for it's purpose.  Once I had all the wires in place I put the PC board back in and screwed it down.  I had one more issue.  The Ten Tec transformer had a buck winding for the fan so that the fan had a fast and slow speed as slected by a switch on the PS.  The Ameritron transformer did not have this.  So instead of not giving Rocco the same choice he would have normally had I decided to insert a high power Dale 25 watt 300 ohm resistor in series with the fan.  I rewired the original fast/slow switch so that on fast speed it would short out the resistor and speed up the motor.  One last issue loomed.  The 800H transformer has a safety overload sensor built in it.  It is some sort of temperature sensor.  If the transformer heats up too much the normally closed sesor opens up and breaks the antenna relay line so that you can not transmit with the amp until the transformer cools down.  I didn't want to waste this feature since Rocco told me he was going to do SSTV with this amp.  I thought Rocco better know if the sensor says the transformer is too hot.  SO what I did was to use the 12vac winding on the transformer that Ameritron uses for control voltage and I rectified that voltage and made a small 12vdc supply.  I repurposed the Hi/Lo relay I removed from the circuit board that was no longer needed since the 800H transformer only allows one HV setting.  It is a 12vdc relay with NO/NC contacts.  I wired the pimary of the relay through the sensor that is NC to the +12vdc.  I then got beeper from Radio Shack that sounds like a truck back up signal.  I wired it through the NC contact on the relay through to the +12vdc supply.  Now, If the transformer over heats the sensor goes open, the relay loses power and drops out the beeper starts beeping until the transformer cools down and the relay kicks back in and stops the beeping.  So after all this I fired up the RF deck with the new power supply and the amp plays real nice.  HV is up to 2500v and the filament voltage is 13.2.  The amp makes an easy 1500 watts with 40 to 45 watts.  I ran the power up to 1800w and the grid current is only about 30ma.  The amp loads real smooth and plays great now.  Rocco is back in business.  I'll be sending the PS and amp back to him on Monday or Tuesday.  I am hoping he will take a photo and post it here of what the transplant looks like.  I suspect he will let us know how the amp works with this transformer when he does his SSTV.  This was a real neat project and I enjoyed the challange.
Lou W1QJ
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K8AXW
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Posts: 3839




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« Reply #85 on: February 23, 2013, 09:10:25 AM »

Great job Lou!  I hope Rocco does post photos of this "transplant."  I  would enjoy seeing how this was done.

Al - K8AXW
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WU2M
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Posts: 29




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« Reply #86 on: February 23, 2013, 09:18:47 AM »

Hi Everyone,
 
I will be posting pictures of the successful transplant next week when the amp arrives home. I am looking forward to getting it back and excited to get it hooked up and running! I can't even begin to thank everyone enough for all the advise given to me and especially to Lou for all the time and work he put in to get it up and running again.
 
 Pictures Soon!

73,
Rocco WU2M
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K4RVN
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Posts: 772




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« Reply #87 on: February 23, 2013, 12:28:22 PM »

Thanks for posting your methods and results Lou. I have been checking often for the final chapter of the repair. Glad to see a doer who was not afraid to improvise. I'll also be anxious to see the photos from Rocco. Now if I can just get a mic wired up for my old AF67 Multi Elmac I'll be happy for a time.

Frank
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WU2M
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Posts: 29




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« Reply #88 on: February 27, 2013, 02:39:18 PM »

Hello Everyone,
 I got the Titan back from Lou today and all I can say is WOW! It works great. The work he did is great and it looks as though he took great care in his work. Everything is neat and clean and works like a charm. I am going to see if I can upload some pictures that I took. If not, I will upload them to a different site and post some links to them.
 I want to publicly thank Lou for all that he has done for me. Lou is a class act all the way! Thank you Lou. I am getting great reports with it already.
 Now off to figure out how to upload these pictures here.

73 Rocco
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W1QJ
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Posts: 1446




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« Reply #89 on: February 27, 2013, 05:38:10 PM »

Thanks Rocco.  The guys are waiting to see what is going on with that power supply.  I'll answer any questions when we see the photos.  But on my last post I went through the whole procedure I took to deal with all the issues.  Basically you will just see a bunch of wires going from here to there.  The PC board is way down on the bottom of the amp and may not be seen very easily.  We have to see how the digitals show up.  Once I bench tested the amp with the new power supply rebuild I couldn't hear any sign of a groaning by the transformer when producing 1800 watts into my dummy load.  I am anxious to see some of Rocco's SSTV pictures when he gets that amp going on SSTV. 
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