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1959 Invicta 638

 
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1959 Invicta 638

Post by AidanLunn » Sun Apr 17, 2016 8:29 pm

So after a long while, this is the next set to be up for treatment on my bench.

I can't find any trace of anyone having restored one of these before when doing a Google search for "Invicta 368 TV", but I'm sure I have seen one of these some years ago on UKVRR (possibly, as I'm sure it was before VRAT was even launched!) - that bronze-effect screen bezel and "goldfish bowl" implosion screen look very familiar. Could there have been a Pye version of this model?

Anyway, pretty much textbook results when taking the back off quite dusty, and a thick layer of coal dust especially behind the mains selector panel.

Upon switching on, first light and a recognisable picture were obtained! I have no service info as of yet, so no further progress will be made until I have the necessary paperwork for this model. (A request will follow in the appropriate section shortly after this post). The CRT looks to have plenty of life, but then again it is an AW43-88.

And again my camera has not taken too kindly to the brightness, so the photo makes the frame cramp look brighter than it actually is.

So far this looks to be a good 'un - possibly just a few caps in the frame and sync stages and it will be a worker!

EDIT: forgot to attach pics
Attachments
Invicta_1.jpg
Invicta_2.jpg
Invicta_3.jpg
Invicta_4.jpg

 
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Re: 1959 Invicta 638

Post by AidanLunn » Sun Apr 17, 2016 8:33 pm

Pics of the inside. It might not be clear where it is on the set but pic 3 is of the underside.
Attachments
Invicta_5.jpg
Invicta_6.jpg
Invicta_8.jpg
Invicta_9.jpg
Invicta_10.jpg

 
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Re: 1959 Invicta 638

Post by Duke Nukem » Sun Apr 17, 2016 9:31 pm

I recently had a bash at a very similar chassis - Pye V310S. Only had supplementary info for it so had to guess at what some of the components were. Anyhow, also had a V300 manual which had a different timebase panel - extra valve, like yours has, so I'm guessing your Invicata is a Pye V300 chassis.

Be aware that a couple of caps in the LOPT area are a real *&@!£ to access and will need replacement - shortly afte I was taking the first pic the picture began to shrink and I dived for the off switch,whilst what little wax had been on one of the caps finally departed said cap. It's a tube-out job to do these caps, though the CRT comes out easilly enough (particularly if you get someone else to do it :qq1 )

TTFN,
Jon

PS: Should anyone have a correct set of knobs they'd be much appreciated.
Attachments
1.jpg
After a bit of fettlin'
2.jpg
Chassis
3.jpg
CRT-out access to caps
4.jpg
Geting there

 
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Re: 1959 Invicta 638

Post by Katie Bush » Sun Apr 17, 2016 10:20 pm

Hi Jon,

That's a handsome looking set! :aad I can't say I've ever seen one before - good luck finding the knobs for it.. :bba

Marion

 
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Re: 1959 Invicta 638

Post by Lloyd » Mon Apr 18, 2016 8:44 pm

Hi Aidan,

That looks very much like the Invicta version of the Pye PV110, one of which I have here!

I've done nothing with it, whoever had it before me did some work on it, so it basically works, but the brightness control does nothing, and the picture looks too big, so some adjustment is needed. I got an original Pye manual for it from a member of the UKVRR forum last year, and I did promise that when I get round to looking at it and sorting the set out that I'd post the results over there!

Regards,
Lloyd.
Attachments
IMG_2138.jpg
Pye PV110

 
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Re: 1959 Invicta 638

Post by mark pirate » Mon Apr 18, 2016 10:04 pm

That is the same chassis used in the Pam 600F, only the tuner is top mounted.
Be aware that a couple of caps in the LOPT area are a real *&@!£ to access and will need replacement - shortly afte I was taking the first pic the picture began to shrink and I dived for the off switch,whilst what little wax had been on one of the caps finally departed said cap. It's a tube-out job to do these caps, though the CRT comes out easilly enough (particularly if you get someone else to do it :qq1 )

I had to unmount the LOPT to change those caps, less risky than removing the CRT :zx:
Be VERY careful if you clean the tuner, there are a myriad of small coils that could be damaged when cleaning the contacts.

 
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Re: 1959 Invicta 638

Post by crustytv » Tue Apr 19, 2016 8:08 am

Lloyd wrote:Hi Aidan,

That looks very much like the Invicta version of the Pye PV110, one of which I have here!

mark pirate wrote:That is the same chassis used in the Pam 600F, only the tuner is top mounted.

Invicta, PAM as we all know, they are PYE underneath. Just checked the PV100 data in the 59/60 red book which also has the Invicta 638 data. The circuit does indeed look similar if not identical and uses the exact same chassis, valve and diode line-up. Not looked up the PAM but I've no doubt it will be similar if not the same circuit.

 
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Re: 1959 Invicta 638

Post by Till Eulenspiegel » Tue Apr 19, 2016 9:23 pm

The Pye V110 was the first TV set to be sold in the UK to be equipped with the slim 110 degree CRT. The 110 set was announced in late 1958. Early sets were fitted with a Cathodean CRT which had a 0.6amp heater, and for that reason a mains transformer was required.
The Invicta 638 is very similar to the V110 but not identical. All are very good receivers.
The 110 degree CRT first appeared in the USA in 1957. I'm not sure which company developed to the 110 degree CRT. I seem to think it was the Rauland Corporation, confirmation required.

Till Eulenspiegel.

 
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Re: 1959 Invicta 638

Post by AidanLunn » Thu Apr 21, 2016 2:23 pm

Thank you to those who have contributed so far.

Well, I managed to get the two caps on the LOPT replaced. The trouble was the only suitable capacitors I had in stock were physically larger than the ones that needed replacing, so whilst I could have taken the LOPT out from the bottom, I decided not to in case I ran the risk of replacing them and then not being able to fit the LOPT assembly back into the set. So I elected it would be more practical, although more difficult, to take the tube out. First I unsoldered the LOPT connections from the set as it would have been much easier to do if (of course) the LOPT was totally free.

I think the tube mounting is different on the V300 than it is on Jon (and possibly Mark's?) example or chassis, as the CRT on this is anything but easy to get out. As you would expect, the top panel needs unscrewing first, then the four CRT mounting screws, two bottom, two top. The bottom ones are fixed through sections that are bent upwards at 90degrees so the screws can tighten up to them. Easy? So far it is.

The next stage, i.e. actually removing the tube is difficult because those two bottom screw mounts being bent upwards are precisely the things that stop the tube from sliding out. You can't simply "pull it up", because just behind these mounting holes the rimband slots into holes on the chassis. You can't remove the tube by sliding forward out of the slots (because of the screw mounts) and you can't pull it upwards because of the slots. I searched all around the front part of the chassis for the best part of half an hour trying to work out how to remove it. I thought about sliding the CRT about an inch or two to one side and then pulling forward, as the rimband "arms" that slot into the chassis came into the slot from a side, but on each slot the arms slot in opposite sides, so as you slide the tube one way, one of the slots meets the rimband end of the arm. Slide it the other way and the same happens on the other rimband slot. The "arms" that slot into the slots are so long that it meets the rimband end of an arm before it meets the clear end of the other rimband "arm".

Short version is: The tube wouldn't come out.

(Why didn't they just design this with the arms that slot in both facing the same direction? That way you could just unscrew, then slide to one side by a few inches to release the rimband from the slots and then the tube assembly would be free!)

I hope that's a detailed enough description of how awkward I found it to get the CRT out of this.

In the end I came to the conclusion that the only way to get the tube out is to slide forward *but* first to bend the bottom screw mounts downward using pliers or somesuch. This frees the CRT and rimband to come out of the rimband slots. Overkill maybe, but in the face of what I was confronted with, it looked like the only option, so I'd welcome anyone explaining or showing me an easier way to get the CRT out as I tried for a good length of time and found no answer.

I then unscrewed the LOPT, did the capacitors, slotted and screwed the LOPT back in, put the CRT back in, bent the screw mounts back as best I could, screwed the tube back in, screwed the top panel back on, then resoldered the LOPT assembly.

All that hassle just to replace two capacitors on a s&£!$ng LOPT! I get the feeling that if the whole thing had been designed from the servicing point of view, then a lot of time and anger could have been saved! But no, they had to design the most awkward chassis I have restored so far! *rantover*.

I also replaced a wax capacitor, C91, directly below the LOPT assembly. I only had an old used TCC yellow plastic capacitor as a suitable replacement, so until I got some new ones I had ordered, I thought I might as well use this one to prove that the circuit works. When I got some of these capacitors as part of an eBay auction for some valves, I tested each one and they all seemed to work OK, so possibly one slipped through the net and got fitted to the set. I mention this because there is now no line whistle at all. So on to the next stage, measuring the valve voltages in that part of the set, but first, yet another deviation, except this one was much more fun than replacing the caps on the LOPT!

To measure the LOP stage valve voltages you obviously have to turn the set on to its front. The strange thing was that when the set was upright, there was sound of the test tone from the Aurora through the speaker. on its front and switched on, there was no such thing as sound. Before I even went to check the speaker and audio stages, I noticed something I have never seen before.

When switching the set on with it upright, all valve heaters lit normally and, apart from the LOPT stage, it all worked fine.

However, with the set switched on but on its front, I noticed something strange as it was warming up. The heater in valve 6 would come on first, be brightest for a few seconds, then flicker back to about normal brightness as the remaining valves all warmed up. Then, after about 5-100 seconds, the heaters in valves 1, 2, (both tuner valves) 3 and 4 (both vision I.F.) would extinguish but they were still passing current (the valves before and after valves 1-4 were brighter than usual) as the valve chain as a whole didn't go out. Of course it couldn't be a dry joint in the heater circuit as all valves would go out if there was, so it had to be a defective valve (far more likely) or heater decoupler (far less likely).

Using the clue that it worked OK when upright, I powered on with it upright, waited for all valves to be fully heated then began slowly tilting the set forward. Did the valves go out? Did they hell as like! So it seems whatever it was was only affecting the valves when they were in the first few seconds of warm-up.

And lo and behold, replacing V9 (EF80, first sound I.F.) solved this. The valve heaters now work fine whether upright or screen facing downwards. Of course sorting this was essential as the power supply and heater chain need to be working properly in order to take voltage readings to diagnose another fault.

So a real mixed bag of a day, from the depths of pure hatred, spitting blood and screaming blue murder and a whole shedload of other blue words at the thing when going through the labour intensive task of replacing two capacitors on the LOPT to the much more fun task of diagnosing an electrical fault.

Even just recounting yesterday's events has soured my mood! I think I'd better calm down before tackling the lack of EHT! Even though my typing/prose style is that of someone who is permanently grumpy, I am actually quite a docile person so something really has to push me hard to come to the point of swearing and cursing out of anger. Yesterday, this set pushed all the right buttons!

One thing's for sure though, this chassis is not service-friendly! If the lack of EHT is down to a simple mistake on the LOPT - I didn't want to go through this again as it was so labour intensive so I made sure I wasn't making any - I am not going to go through the rigmarole of stripping this set down again!

 
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Re: 1959 Invicta 638

Post by Lloyd » Thu Apr 21, 2016 6:19 pm

I think you enjoyed it really :bba

That probably explains why the CRT in my Pye is loose in its mounts! I've not had the chassis out to investigate why yet.. I guess some one had as much fun as you did getting it out and couldn't be arsed to put it back properly!

Hope you get the line stage sorted!

Lloyd.

 
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Re: 1959 Invicta 638

Post by AidanLunn » Thu May 05, 2016 7:10 am

After a short break from this set, I had to force myself to get to the next stage (I think you can tell I really don't like working on this chassis), so I was determined to get the line stage running. A few taps with a screwdriver croc-clipped to chassis on the caps of the three valves in the LOPT cage revealed there was EHT present but no line whistle at all. How?? I reasoned that there was EHT there, much lower than it should have been, so there must have been oscillation present but too quiet to hear.

I began investigating around the line oscillator and lo and behold, C84 was totally s/c. Replacing this restored line scan!

 
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Re: 1959 Invicta 638

Post by freya » Thu May 05, 2016 7:37 am

Its great to read up on a different set with its unique issues, if you include component reference numbers then maybe a circuit snippet so we can all see the circuit your working on. Well done on persisting though. :aad

 
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Re: 1959 Invicta 638

Post by AidanLunn » Thu May 05, 2016 11:06 am

Hello Stephen, I am working from the manual in the library if you want to see the circuit.

It has taken a great deal of persuading myself to continue working on this pig of a chassis!

 
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Re: 1959 Invicta 638

Post by AidanLunn » Tue May 10, 2016 12:22 am

As some of you may well know, I really do not enjoy working on this set at all, and now it seems as though it is not going to work. Firstly, I just have not taken to being able to work with this chassis at all. Almost everything is very difficult to access from a service position. But now I think the set's fate is sealed.

The next bit is important as I think this was a contributory factor to the set's demise.

When I was trying to remove the LOPT to change two capacitors (I still can't get over how much labour is involved in doing that, that takes the urine!!), I first tried to remove the LOPT by pulling it through its hole in the bottom of the chassis, but I struggled to do this. In so doing, I managed to accidentally take out a chunk of the epoxy resin, so that a little bit of the overwind was actually exposed (size of the exposure was about the size of a rice grain, probably not even that). But as my attention was more focused on changing these two capacitors I thought nothing more of it. When I switched back on, there was still full-width line scan. I then thought nothing of the damage I might have done to the LOPTas there was buckets of EHT and the width was still full.

Then, on the day when I ended up replacing C84, there was no line scan. Replaced C84 and there was a raster, although with reduced width. So I set about doing the usual, checking boost capacitor, HT rails (apart from boost HT, there are two that the line stage is fed from) and replacing the line osc, LOP and boost rectifier valves, all made not an ounce of difference. That day i decided to pack up and go to bed.

The next day, I came down and switched on, only the raster was even narrower this time, then only moments later "crack!" and a brief bright blue flash from the part of the LOPT with the exposed winding followed by smoke, and a fizzling out of the picture.!

So I am now at my wit's end with this TV, my patience has run out (a lot of it was used up taking the CRT out to change those two capacitors!). I only ever bought this with the intention of using its CRT for my upcoming Ekco TC346 restoration to replace the CME1703 those sets use, as it's bound to be low emission!), I never actually wanted to restore it, but I tried my hardest to prove it can work. Many here will know that even when the restoration is at its lowest ebb, the point when I feel like giving up, I keep plugging on such is my enjoyment of restoring and using such old sets and my commitment to keeping these sets preserved.

I've experienced enjoyment on all restorations except this one. I just don't seem to be able to get on with this chassis at all. I hope other members can see where I'm coming from having tried to restore or service a chassis that is a nightmare to work with, as I don't enjoy giving up at all.

So tomorrow I will be going with my original intentions when I bought this set off eBay some months ago - breaking it up for spares. I have claimed the CRT for one of my future projects and also the valves, so if there is anything from this chassis that anyone wants, feel free to PM me. FOC + postage.

 
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Re: 1959 Invicta 638

Post by Till Eulenspiegel » Tue May 10, 2016 1:13 am

Don't scrap it, it's too rare a set to do that. I'd be happy to take it off your hands. Actually I was one of the bidders for the set on ebay.

Till Eulenspiegel

 
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Re: 1959 Invicta 638

Post by AidanLunn » Tue May 10, 2016 7:56 am

Till Eulenspiegel wrote:Don't scrap it, it's too rare a set to do that. I'd be happy to take it off your hands. Actually I was one of the bidders for the set on ebay.

Till Eulenspiegel


Well I need the tube anyway (that's what I got it for, really) as the CME1703 airbag in my Ekco is likely (as these tubes always are, according to Trev's UKVRR thread on the same set) to be dead or not far off. This Invicta has an AW43-88.

Alternatively, if anyone has a spare AW43-88 for my upcoming Ekco, this set can get a reprieve and be handed over to Till as s complete set.

This set's your problem now, Till! :P

 
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Re: 1959 Invicta 638

Post by PYE625 » Tue May 10, 2016 8:50 am

What a shame, guess the set didn't like you :aah

I must admit though, I remember the caps on the lopt being pigs to get to and change, some years ago with my old Pam 600f restoration.
I didn't want to remove the tube, but was only just able to change the caps by using a trained ferret and a lot of patience lol.

viewtopic.php?f=5&t=10349&hilit=+pam

 
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Re: 1959 Invicta 638

Post by AidanLunn » Tue May 10, 2016 9:37 am

Well before I forget I have to say thank you to everyone for the encouragement on this one, but it was just too awkward for me to service, then it decided to chuck in the towel.

 
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Re: 1959 Invicta 638

Post by Till Eulenspiegel » Tue May 10, 2016 9:54 am

Hi Aidan,
the set can be put aside until a CRT turns up. We have to accept these tubes are becoming scarce.

Till Eulenspiegel.


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