View Full Version : Is this a Merit HVO-6? If not, what is it?


VintagePC
06-01-2017, 06:02 PM
Was ordering a few things from Playthings of the past and saw he had an HVO-6 listed. Figured I'd pick it up to meet the minimum order requirements, since I am a little uncertain about the flyback in my Hallicrafters, and spares are always nice.

The SAMS only has HVO-6 listed as a spare, nothing else.


Got it today and opened it to find the attached... doesn't look right to me. The box certainly says HVO-6 on it, but the writing on the transformer itself is too smudged to make out (Not on the side facing the camera, silly me.. I can make out the "HVO" but not the number that follows)

It's only got three terminals and a filament winding... so I can't use it either way, but I did some googling and found this thread:
http://www.videokarma.org/showthread.php?t=248133&page=7

and mine looks nothing like Bob's. So if what I have is not a 6... what is it?

http://www.videokarma.org/attachment.php?attachmentid=194805&stc=1&d=1496354472

EdKozk2
06-01-2017, 07:31 PM
It looks more like merit HVO-8 air core . Something like the RCA 74951 for direct drive circuits. Stancor made one with the number A-8131.

VintagePC
06-01-2017, 10:32 PM
Looking closely, I think you're right. the "6" on the label is faded and could very likely be an 8.

Kevin Kuehn
06-02-2017, 06:04 PM
Yep that is a HVO-8 which is equivalent to a Fly 2. A HVO-6 is equivalent to an Fly 3 and were originally a GE replacement. I believe I have a Fly 3 or HVO-6 here if you want to swap me for your HVO-8.

VintagePC
06-02-2017, 07:07 PM
Sounds good, I was contemplating reaching out to Gary at POTP to see if he'd take a return since it was mislabeled and I (mostly) needed to fill out my order for a part I can't get the set running without (focus control).

I'm planning to work on the set this weekend, if all goes well, in a day or two I might actually know whether I need a replacement flyback or not. If I do, swapping is just as good for me, or if I don't need to swap, I'd do it for the price I paid plus postage, should you still be interested. I'll be in touch.

(Interestingly, the Thor column in the Sams does not list FLY-3 as a replacement option, only the HVO-6. Perhaps the 3 wasn't on the market when the SAMS was published?)

Kevin Kuehn
06-03-2017, 11:49 AM
(Interestingly, the Thor column in the Sams does not list FLY-3 as a replacement option, only the HVO-6. Perhaps the 3 wasn't on the market when the SAMS was published?)

Also interesting is that your sets OEM part number(55C172/B) is listed in my Thordarson catalog as requiring a FLY 12 as replacement. :scratch2:
I tend to believe Thordarson literature over Sams, but it's possible they both will work in the circuit. Often times it comes down to physical differences in the way they mount.

VintagePC
06-03-2017, 11:55 AM
Well, the manufacturer ought to know what works :) No reason there can't be multiple subs.

For flybacks it also just depends on what taps are available, so long as you have the right combinations of windings for your design any would work.

Kevin Kuehn
06-03-2017, 12:03 PM
Maybe someone can cross that RAM number that's currently in your set. It sure looks to be in good condition.

EdKozk2
06-03-2017, 01:28 PM
Maybe someone can cross that RAM number that's currently in your set. It sure looks to be in good condition.

Maybe this will help. Bob Anderson posted this on ARF at one time.

http://farm8.staticflickr.com/7232/7182408581_cf72eda594_k.jpg

VintagePC
06-03-2017, 01:44 PM
Yep, definitely looks good. Reason I'm a little hesitant about it is the primary measures about 4 times what the schematic/parts ref states it should.... but I guess if it makes the correct voltage it's not an issue.

EdKozk2
06-03-2017, 01:55 PM
The step-up voltage ratio is what your after. The resistance and wire size in the windings determine the current and resonant frequency.

Bill Cahill
06-09-2017, 11:49 PM
Also interesting is that your sets OEM part number(55C172/B) is listed in my Thordarson catalog as requiring a FLY 12 as replacement. :scratch2:
I tend to believe Thordarson literature over Sams, but it's possible they both will work in the circuit. Often times it comes down to physical differences in the way they mount.

Speaking of problems with part numbers.
I have a new old stock RCA flyback That they swear was used in a 10" table set with a single 1B3 rectifier. Hlowever, this flyback has two filament windings, and, two hv rectifier connections. Also, the single flyback is shown to put out maximum Ten kv.
Ne flyback gives a total of 13-15 kv.
Bill Cahill

Kevin Kuehn
06-12-2017, 09:26 PM
Bill,

The double windings are a dead give-away that it was really intended for a larger CRT set. Otherwise the frame and core look identical. We recently discovered this while looking up fly numbers for another member, but I can't find the other post right now.

Bill Cahill
06-13-2017, 03:54 AM
Well, thank you very much.. If you find it, I surely would be interested.
Bill Cahill