Test Equipment Video Circuits 'Tripler Tester' V15

Looking at the picture on the back of the tripler, I connected the V15 blue drive connection to the back spare tag of the Granada tripler, which I believed to be input (drive). I then connected the V15 black neutral connection to the green wire on the Granada tripler which is GND. Finally, the V15 red EHT to the Granada triplers EHT.

I set the V15 to tripler, powered on, and pressed test, the meter read 100%. That indicates the line frequency pulses introduced into the tripler, produced 100% efficiency, thus the Granada tripler is good, and the V15 is working.

I think I kept a duff 8500, I'll see if I can find that now, to see what it produces.

D.U.T. Granada Tripler

Rare indeed, in fact that is the first I've ever seen other than pics in TV mag. I have a faulty tripler I kept from one my ITT FT110 sets, it generates EHT but has obvious tearing at high beam currents. I wonder if it would pick that up as a drop in efficiency on the meter? 

Re quadruplers, the only sets I know that used them were the Baird 700 series and later versions of the RBM dual standard hybrids. 

Posted by: @jayceebee

I have a faulty tripler I kept from one my ITT FT110 sets, it generates EHT but has obvious tearing at high beam currents. I wonder if it would pick that up as a drop in efficiency on the meter?

Hang on to that, we can test it next time you're over this way. I thought I'd kept a few of my failed ones, but it looks like I only kept one, and that's de-potted with parts removed, ready for rebuilding.

Nice bit of kit. Only ever seen one before. Cap dated April 1972.

At a glance it looks as if the mains is voltage doubled for the HT. At least the case is earthed!

This evening, John dropped off his failing ITT FT110 tripler, so I can see if the V15 tripler tester detects the fault. You can see the tripler fault in this post of Johns.

I'm pleased to report the V15's absorption test reveals the FT110 tripler is only 60% efficient.

Thanks to @jayceebee for dropping off the duff tripler, up until now all the ones I've tested thus far in my stock were 100%. At least I now know the tester is working as it should, and importantly I've a lot of good triplers.

@crustytv Certainly does what is says on the tin, I have to admit that I did have doubts it would pick up the issue but there you go. The tripler would work ok until there was any peak white in the picture leading to the lines and a screeching/arcing noise. I originally suspected it might be CRT, this was common with ITT’s own and also Videocolor manufacture.

Try it again after cutting the anode cap off. Might be the resistors inside the cap failing but often when they showed signs of overheating it was due to internal problems in the tripler body.

Posted by: @jayceebee

Try it again after cutting the anode cap off. Might be the resistors inside the cap failing

You're rarely, if ever wrong John 👍 

Indeed, with the anode cap removed, and as such the resistors within also removed, the tripler now tests 100% good.

Next time you're here, you can have your tripler back for your spares, especially as you have two FT110's to maintain.

Whilst we're on the subject of triplers, I've just put this up in the workshop, it will surely help me identify a lot of the triplers I have in stock. An RS chart from 1975, perhaps some of you ex TV engineers might have the ability to instantly identify triplers on sight, us mere mortals can a few, but not all. It also covers a few I.C, Electrolytics and droppers, for popular sets of the time.

I happen to have a 1975 RS catalogue with the prices of the triplets on that RS chart. 

When did Radio Spares give up on consumer electronics parts ? I can only ever remember RS being professional / industrial electronics, I had an Uncle who would give me RS catalogues in the early eighties and all those parts were gone by then I'm sure. Did they abruptly stop or just phase out such components. I guess there was still a market as Willow Vale, HRS, Wizard and of course CPC continued suppling such parts for years

@mfd70 

Thats a good question, I left the trade 80/81 and for the life of me I cannot remember if I used RS at that time.

Posted by: @crustytv

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This is a piece of test equipment I've been looking for, for a very long time. I had thought the chances were next to nil, to ever encounter one. I've not seen another in all the years I've been looking, and I only found one reference in a Television magazine from the 70s.

Normally I wouldn't touch anything coming out of the 'Video Circuits' stable, especially not their CRT tester/rejuvenator. However, the Tripler tester is something that has intrigued me and as far as I know, unlike CRT testers, nobody else had ventured into providing an instrument to test triplers.

The V15, if you've not already worked out from the thread title, is an EHT tripler tester. It tests drive absorption and final output on load. It produces pulses of around 800V pk-pk at 625-line frequency. There are five buttons, mains, 1-3 for DUT and the test button. Efficiency results are displayed on a meter, as a percentage. In fact, it tests not only triplers, but doublers and quadrupler's too, though I only know of one set that used a quadrupler.

1. Single/Doubler
2. Tripler
3. Quadrupler

 

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I doubt many, if any, of these have survived, there's certainly nothing online. Thus, as far as I'm aware, this is an exclusive to VRAT. I will document as usual, with lots of photos, and put through its paces. The first thing to note is just how tiny it is. From the only photo I had from the TV mag, I assumed it was a large piece of kit. In fact, it only measures 8" wide x 3.5" at its uppermost height and 3.5" deep. Inside, there's not a lot to report, a TX, a switch bank, a couple of diodes, two electros, a few caps, resistors, pot to the meter and a single Brimar 12AU7 (ECC82).

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As you can see from the internals it looked to be in remarkable condition, throwing caution to the wind, powered it up, no dramatics. Now to give it something to test.

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Obviously no manual, so no operating instructions or circuit data. Connectivity although appearing to be simple, I'm a little uncertain of one of the connections. Red to EHT is self-explanatory, Blue to drive, I believe would be to the triplers input? Black to neutral, this is the one I'm unsure of, any thoughts? For example, here is a Granada Tripler of unknown state I'd like to test.

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Hmmmm not sure Yellow ? Grey is easy EHT, so connect that to Red, Green is Ground? The middle tag is Focus, The back tag ?

It would be nice to reverse -engineer this unit. It would be simple enough to build one, once all the component values voltages etc were known.

David.

@ancientengineer 

A while back just for my own curiosity, I did a simulation based on a circuit gleaned from pictures posted. Not sure of supply voltage though but with 260V it was possible to determine the effect of various simulated tripler faults e.g. leaky capacitors and diodes. If anyone is interested I will need to retrieve the LTSpice project off my netbook and post.

Rich

Sounds interesing, but only if you have the time.

David.