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 Post subject: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer diagram
PostPosted: Sep Sat 12, 2020 8:13 pm 
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Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
I am looking for pinout diagrams of Hickok 536 and 539 transformers. I have a KS-5727 (like a 536) tester with a heavily damaged transformer, half the pins are broken free from the transformer body,and even worse, the tap leads are broken at the point where they exit the transformer coil body . I purchased a good transformer from a KS-15559 (,539). The transformers physically look similar (8terminals on the right, 7terminals on the left bank). However the winding configuration is obviously different. Military TV series testers include transformer diagrams in the manual, but the civilian tester's don't, and the schematic for both testers looks the same, as it does not reference the terminal numbers.
Thanks
Ken N5VSW


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Sep Sun 13, 2020 3:18 pm 
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Joined: Jan Thu 24, 2019 1:22 pm
Posts: 316
Location: Centennial, Colorado 80122
This is the transformer pin layout for the Hickok 539B, 539C, RD1575 and the WE KS-15750 tube testers.


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Sep Mon 14, 2020 1:14 am 
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Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
Bill, thank you.
Ken


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Oct Tue 27, 2020 12:43 am 
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Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
I wanted to give an update to this thread. As you can see from the pictures, the transformer was damaged severely. I sent it to be rewound, received it back, and after going through the standard switch cleaning and replacing out of tolerance resistors, the tester is up and running. One complication, once the transformer was repaired I discovered the 83 tube was shorted. If you have a bad transformer, it isn’t exactly cheap to have it rewound, but it is possible. It was about 250.00 all in (including shipping), and the time was a bit over a month. Best regards everyone. Ken


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Oct Tue 27, 2020 4:12 am 
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Joined: Jun Sat 15, 2019 7:43 pm
Posts: 1002
A 83 tube can show shorted if it hasn't warmed up enough to vaporize all the mercury.

DM


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Nov Tue 03, 2020 7:20 pm 
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Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
Hi DM
Thank you, the Mercury Vapor Rectifiers are unique, I enjoy them, and have a respect for the capabilities of this “old technology”. I experienced what you are describing, when troubleshooting another tester in my collection, a Hickok 533A, where the transformer winding tap wires were broken by shipping damage. I was measuring the phase pulses of the 83 tube using a scope, and found that the phase pulses were high/low by >80Volts. I put the 83 tube on a tester to warm it up, and that cleared up the uneven pulses (Mr Thorusen helped me through the troubleshooting).
Not the same as showing shorted, but pretty dramatic, and I’m sure the tube could appear to be shorted due to not being vaporized properly just as you say.
I am allowing that tube to sit idle on the newly repaired KS-5727-L1, and will see if the short condition clears up.
This tester is a pleasure to use, now that the transformer has been rewound.
I held off identifying the company that did the re-wind, until I put hours on the tester, and proved it really is working. I am now confident in the repair.
I had J and K Audio Specialties do the work, and they did a fine job on this transformer, and another transformer that goes into a TV3 (non a-b-c) tester. It cost around 180.00 per transformer. They are located in Taipei Taiwan, so the shipping was around 60.00 usd each way. These folks are great to work with, and communicate well at each step. I cannot recommend them highly enough.


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Nov Tue 03, 2020 7:34 pm 
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Joined: May Wed 18, 2011 2:40 am
Posts: 5065
Location: Littleton, MA
How do you like your Hickok 455 VOM? I haven't restored mine yet.

_________________
Steve Byan https://www.byan-roper.org/steve/steve-at-play/


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Nov Tue 03, 2020 8:04 pm 
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Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
Hi Steve
Thank you
I love the Hickok 455. It is pretty good for all around utility measurements. I got lucky, this one came from a Milwaukee technology school, and was fully operable and accurate, when compared to my fluke dmm. It is a high-z meter as you know, 20K Ohm/Volt on AC and DC, and measures high ohms at 30V (good for fast-rough capacitor checks). It’s handy as it sits on the bench, has a low profile and does not tip over. It has a circuit breaker. I thought the meter movement might be sketchy, but it is very solid.
I also restored a Hickok VTVM that is a fine instrument as well. I replaced the small pin jacks with safety banana plugs just to be safer, with these old tube projects we often have wires running here and there on the bench. A live un-shielded pin connector tied to b+ Is scary to me. But the VTVM works well, I recapped it (all paper caps) just because it is a ritual, and went through the alignment steps (it aligned in all functions).
Ken


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Nov Tue 03, 2020 9:20 pm 
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Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
An update: After 2 hours sitting on the tester with filaments lit, the bad 83 tube still shows a short. I don’t think any additional time “cooking” will clear up the short condition.
Ken


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Nov Wed 04, 2020 6:43 am 
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Joined: Nov Fri 30, 2012 3:35 am
Posts: 497
Location: Phoenix, AZ
The short indication is with the rotary switch on your KS-5727 set at position 4. Which tube elements does that denote? Do you also get a shorted indication at any other switch positions? I agree, after two hours of cooking, leaving it to cook longer is not likely to resolve it. But is there any visible cause for a short inside the 83? The construction inside is pretty simple; there are no grid structures, and it appears that the glass on the top of the envelope is clear and might allow a person to view (using a magnifier) down basically the entire length of each cathode inside each plate. Is there nominal physical clearance all around between the inside surface of each plate and the cathode? This is speculation, but maybe there is a tiny whisker caught somewhere inside which (perhaps) could be dislodged by gentle tapping of the tube. (If you do this, be careful to not break the tube, lest mercury be released.) I ask these things because there simply isn't much to go wrong with an 83, other than loss of emission due to many, many hours of use. I have never seen an 83 indicate shorted after warming up. Good luck.
R/ John


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 Post subject: Re: Hickok 536 (KS-5727-L1), vs Hickok 539-C transformer dia
PostPosted: Nov Thu 05, 2020 6:53 pm 
Member

Joined: Jul Thu 30, 2020 3:35 am
Posts: 38
I was asked about contacting J and K Audio. The approach I took was:
1. Emailed them including pictures of the transformer, and the transformer portion of the Hickok Schematic.
2. I received the estimate
3. I sent an email affirming, then sent the package to Taiwan. At their suggestion, I identified a value of $10.00 to avoid import tariffs.
4. I used USPS online shipping which includes creation of customs forms(not tough to fill out).

Email: jandkaudiodesign@gmail.com
Address:
Attn: Yang Zhengfa
2F No.17, Ln124 Lanzhou Street,
Datong District, Taipei City,
10361 Taiwan R.O.C.
Tel: 02-25983284


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