Project [Sticky] 1969 Philips G22K511 Missing I/F & LOPT, Conversion

Superb, congratulations!

Thanks to you John, your mentoring over the weeks and months is what kept me going. I think the TV finally sensed, that if it didn't play ball some serious trouble was coming its way as I had finally run out of patience, it was work to day, or you're going to die.

Just need to get this height sorted, then I can sort of relax and move to the decoder diagnostics

Waveform 23 spot on at 32V

Just checked boost, it is spot on at 590V. Voltage across C7110 is 175V not 190V but close for now.

How remiss of me, this recent success not possible without the fantastic design from Keith @ctc15, if you're reading this at all Keith, I'm so very grateful for your CVC5 conversion advice, it was spot on 👍 

This is getting ridiculous, the LOPT has died, I was progressing with sorting out the height by adjusting on test the value of R4102 and R5034. Almost had good height when there was a screech from the LOPT area, the raster disappeared and the isolation transformer wanting to go into full Chernobyl. Quickly powered off and installed my Kilowatt meter, powered up and it showed 426W and climbing.
This is where I had managed to get was before the LOPT died.

GAME OVER AGAIN...... Think I've had enough!

Oh and before anyone starts suggesting the TV is a LOPT killer, as John pointed out to me, it didn't kill the PYE Wayrad and that was running for significant lengths of time and survived the abuse of those resistor burn ups. No Philips LOPTs are ....... It's a family forum so I won't.

So Close. 😰 

No way ! 😥 

I must admit when I saw the LOPT and realised the CVC5 LOPT was in effect a Philips, my heart sank, but thought maybe I will be lucky, deep down I had a feeling it might go the same way, and it looked like it had been stored in less than ideal conditions.

After seven months I really have had enough, this is getting boxed up and put away. Maybe it will come out again when I can find a good and perhaps new CVC5 LOPT, though the chances are slim.  I have far more deserving sets of my time and attention waiting in the wings.

Nooo!!!! 😥 😪 😫 

It was looking so damn good as well!

Regards,

Lloyd.

@crustytv 

What IS it with Philips LOPTs? You would think that with layered windings, polyester insulation and epoxy sealing they should last forever.

Experience with the Australian made ones was the same. The main contributing factor though was if the regulation (which most designs had) was maladjusted they would fail quite quickly. The only Philips LOPTxs in colour sets we saw here were in solid state designs and I never had to change any of those. But I note WES components still have them as a spare part.

B&W days:

HMV here used a Philips NT3101 LOPTx in the P series chassis in the very early 60s, unregulated. The M series chassis used the same circuit but with MSP deflection components. Failure of an MSP LOPTx was unheard of, but the Philips ones failed so often our service vans carried 4 or 5 of them in van stock. Philips eventually gave up arguing and released the NT3010A replacement which had an extra tap for the EL36 anode especially for the HMV, listed in the instruction sheet as for "240v unregulated" operation. No more failures.

As a keen young tech I was known to add regulation (a VDR, a couple of resistors, a cap and a pot) to HMV P chassis and remove the width coil. My supervisor didn't approve, nor did he stop me. It really should have been there when the set was made because, with the DC coupled video and a good CRT, the raster would "breathe" with APL changes. Adding the regulation fixed that.

HMV relented in subsequent models and included regulation, although it was a notable exclusion in the W1 hybrid which did eat its MSP LOPTxs. HMV blamed heat and released a mod which consisted of a matt black EHT cage!

So, might you have an issue with the primary tuning and the regulation setting?

Posted by: @irob2345

So, might you have an issue with the primary tuning and the regulation setting?

I don't think so, boost was set as per book at 590V and line freq was bang on.

Besides the "Brand New", never used WeyRad PYE clone LOPT had been running for a number of weeks, for very lengthy episodes whilst testing. I never once worried about that, unlike when I saw the ITT CVC5 LOPT which is basically a Philips, my heart sank but hoped for the best. The Weyrad even suffered some abuse with resistor burn ups, it still didn't miss a beat. I would have stuck with that LOPT had the Pulses for Flyback discriminator not been so woefully low. I guess it's still an option to wind a couple on the empty limb. I mean, look at the float below, pretty darn good from the Weyrad.

I think, if I had a problem as you suggest, surely it would have killed the Weyrad LOPT also?

As for Philips LOPTs, well they didn't get their reputation for nothing, it's not something I've just invented. I'm not saying all were bad, but I would say the good ones are an exception, and if you got one your lucky.

Now when you get into poorly stored pulled G6 LOPTS your chances shrink even further. I've three Philips LOPTS, all the primaries are toast, all stored in a barn. The CVC5 that died yesterday also looked to have been poorly stored by the evidence or rust. I need a NOS Philips or CVC 5, I think pulls and poorly stored ones are all going to end the same way. That or I revert YET AGAIN! all the cct changes for the Weyrad and add some manual wound pulse windings for the Flywheel.

In my present state of mind, I can't face reverting nor winding, or spending any further time on the TV. It's going to be put away, I may get back to it but as I said in a previous pose, after seven months, I'm sick of it. I don't think anyone could accuse me of giving up, nor sticking at a problem, I think I've demonstrated quite the reverse.

Final chassis & TV shot before the back goes on.

That is a real shame 😥 especially after all of the work been put into it by yourself, JC and others.

I certainly don't blame you for 'shelving' it for a while 👍 

@crustytv 

I have to say I've admired your persistence with this set but unless you go for a rewind of a genuine G6 LOPT, I'd put this set to one side, have a few TV-free days to clear your head and then pick something else from the collection to look at for now. 

Damn, I'm stuck for words.  I expected to drop back into this thread with everything looking peachy. I even spent last night raking through what I remember of the common decoder faults in readiness for the arrival of colour.

Not much comfort, I know, but at least this part of the the thread would seem to prove that things are otherwise okay in the sync department, and that with appropriate pulse windings, a good lock can be achieved. It seems likely that reworking the PYE substitute LOPT with a few hand wound turns to produce those pulses would have worked. In a sense, it's a pity that line of enquiry wasn't explored instead of, or at least before, the ITT sub.

I can't help but feel that success wouldn't be far away if we could just get through this hiatus.

I know from personal experience that the G6's 'Achilles heel' is/was the LOPT, and critically, getting the line output stage properly set up. Most G6s would work happily and without issue, but there were some, and this one may be one of them, which were oh so finicky (maybe why it was scrapped?) and needed everything to be 'just so'.

I can't help but wonder if there was some obscure aberration in them that allowed certain voltages to fluctuate unseen in operation, and push the LOPT beyond its tolerance. I wonder too, if that's why my hand wound LOPT died after a few hours of running, but also, that LOPT's primary wasn't sealed, and was easily unwound to count the turns - Perhaps not an original Philips, but also, there was the NOS from CHS which fried after a very short life.

Postulation.......

How critical is the harmonic tuning in these LOPTs? and what would be the worst case scenario if the tuning was "off frequency"?

After a 4-week wait, another ITT CVC5 LOPT has been sourced. It tested good by the owner and this time, this one looks to be in much better condition (no rust) than the previous one I used. I'll post an update when it arrives, at least it's a simple hook-in now. Maybe third time lucky this one will hold, and I can finally get on to diagnosing the decoder.

Hi Chris, do you think it is applicable in this case to warm the LOPT by passing a small current to drive off any possible moisture? Or is this more modern type much more resiliant to such a thing?

Is it also worth performing an insulation test before and after such treatment?

Just thinking out loud.

Hi Andrew, being that these LOPTs are encased in a hard white resin, I'm not sure whether they suffer the same moisture ingress troubles as pitch coated ones, but who knows. I'll certainly do an insulation test, this one thankfully looks to have been stored well, unlike the previous one. Having said that, if it was a Weyrad I would be 100% confident all would be well, but it's not. They are bulletproof, as demonstrated by the Weyrad PYE clone I had working, it even stood up to abuse.

Posted by: @crustytv

Hi Andrew, being that these LOPTs are encased in a hard white resin, I'm not sure whether they suffer the same moisture ingress troubles as pitch coated ones, but who knows.

Dipped and autoclaved I would imagine, to force the resin into the windings. By the same token though, it wouldn't hurt to heat the windings, even if it was later found to be of no benefit. I would go so far as to say that however good these later LOPTs became, moisture and time are relentless adversaries, and as has already been said, the previous identical LOPT hadn't been stored all that well - It may have succumbed to moisture ingress?

@crustytv 

absolutely awesome project - others would have thrown in the towel many times along the way - but you guys hung in there and I feel a result is close - every single post added to the shared knowledge and understanding of ‘how it worked’, or didn’t as the case may be, especially the excursions into ‘frankenland’ which are surely the way forward as the availability of original parts and assemblies continues to dry up

Little update to the G6 project:

I will be getting back to the G6 lopt transplant in due course, it will likely be a winter project. Also, I have a couple of new TV's arriving for the collection, in little over a week. A particular model I've been searching for, I'm keen to have a play with them, so I'm holding back returning to projects or starting new ones.

In the meantime though and relevant to the G6, I found a period  stand on e-bay devoid of its TV's. Initially I thought it was for the Ferguson 3710, but it turned out that TV was a tad too wide, wrong colour and wrong legs.

However, miraculously, not only was it the correct colour but also the exact, and I mean the exact width for my 22" G6. This afternoon I had a little rearrange in the shop and the G6 is how happily married to the stand. OK, it's not original (they had much more spindly legs) but I think it looks fab. I'm very pleased with it, and If I ever get it working reliably, I'm looking forward to getting into the 70's lounge for a period of time, it'll give the Bush console a long earned rest.