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Ferguson 3645 16" portable.

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Katie Bush
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Hi Brian,

I'd change those 'Callins' in the audio output, if it were mine, though "practice as I preach" because I've just remembered, my 1400 still has its own in situ. ? 

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Posted : 18/09/2018 7:56 pm
Focus Diode
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Hi Marion,

I've already purchased some 47uf capacitors to replace the 30PL1 cathode bypass. I'll fit it when I get back to the set.

I also have a new boost capacitor to fit. Much to my surprise the existing one is a colour banded lozenge type which, although usually reliable components I wouldn't think they were suitable for that position.

As it is, attempting to measure the boost volts results in arcing at the solder point!

Cheers,

Brian

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Topic starter Posted : 18/09/2018 9:07 pm
Focus Diode
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Good progress made last night, but still some work to do. I replaced the boost capacitor, C82, C101, C104 and the boost feed to the height control.

I was pleased to note the valve heaters no longer represented 40W bulbs. Maybe a leaky capacitor?

Brian

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Topic starter Posted : 21/09/2018 9:59 am
Focus Diode
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Thanks to Malc the 2M2 pre sets arrived. Fitting one in the width control position highlighted another problem.

Near adequate width at full control setting, the 405-line boost voltage low at just under 600V, (should be 670V max). The frame cramp, knowing I've yet to completely eliminate the problem, showed up worse too. Probably as a result of the low boost volts.

There's a few high value resistors to check in the line output stage. Most of the capacitors have already been changed. This I'll do at the weekend when I'm next off work.

On a positive note, the CRT is looking better.

Photo taken a few days ago with the set running for a couple of hours.

The system switch micro switch is corroded. The supply contact broke away on contact. This could explain the earlier instant fuse blowing. It was tuned to a VHF channel with the switch in the 625 position.

I have a couple of spare tuners so will see if I can salvage a micro switch from one, if they have one.

I see an excellent condition 3645 had turned up on Ebay.

Cheers

Brian

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Topic starter Posted : 23/09/2018 5:28 pm
Focus Diode
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Fortunately I've found a cannibalised ex 1400 VHF tuner complete with working microswitch which I'll be transplanting when I get back to the set.

Brian

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Topic starter Posted : 27/09/2018 9:06 am
Nuvistor
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Is it an artefact of the camera or software but the interlace seems to be about 75/25?

 

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Posted : 27/09/2018 11:22 am
Focus Diode
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It's the camera on the phone Frank. Taken at certain angles you get this ripple effect. I take several then select the best one.

Note the set is nowhere near finished. The eagle eyed would've noticed the bottom cramping and the none line linearity.

I'm doing a gruelling seven day week at work this week with little time to watch TV let alone work on one. I'm off next week so hope to get the restoration finished.

Cheers,

Brian

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Topic starter Posted : 27/09/2018 10:27 pm
Nuvistor
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Not easy taking photos off a TV screen. 

 

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Posted : 27/09/2018 10:48 pm
MongooseDC
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I've found that there's a knack to taking pictures of television and monitor displays. In practice I find that phones often work better than DSLRs owing to the slower shutter speeds Although there is the phosphor persistance, the camera needs to have its shutter "open" for at least 1 frame (2 fields or 1/25th of a second) to record a complete picture. I'm looking to set up an experimental device sometime using a long persistance monitor CRT and a phone to capture video and stills from video footage optically. Returning to the original subject; modern lighting can sometimes cause video images to flicker as cameras synchronise to the brightest light sources. Low energy bulbs and especially LED can often have high frequency flicker rates brought on by the SMPSU in the bulb.

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Posted : 27/09/2018 11:21 pm
Focus Diode
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I'm so grateful for digital photography. We shouldn't complain at all!

Not so long ago we had no idea how photos would come out until we got the photos back from the developer!

With camera phones it's often possible to adjust the speed and ISO etc.

Brian

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Topic starter Posted : 28/09/2018 5:34 am
Nuvistor
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I take photos all the time, something I couldn’t do with a film camera, it was too expensive. The other thing is I look at them, either on the phone or computer. I have digitised some of my paper photos from many years ago, otherwise they would never get looked at, gathering dust in a shoe box.

We are not all the same though, some would rather have the paper and want print outs of the photos from the phone.

 

 

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Posted : 28/09/2018 8:33 am
Cathovisor
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Posted by: MongooseDC

I've found that there's a knack to taking pictures of television and monitor displays. In practice I find that phones often work better than DSLRs owing to the slower shutter speeds

Eh? DSLRs have shutter speeds down into seconds.

Although there is the phosphor persistance, the camera needs to have its shutter "open" for at least 1 frame (2 fields or 1/25th of a second) to record a complete picture. I'm looking to set up an experimental device sometime using a long persistance monitor CRT and a phone to capture video and stills from video footage optically.

The problem there is that a long-persistence CRT will blur motion.

Returning to the original subject; modern lighting can sometimes cause video images to flicker as cameras synchronise to the brightest light sources. Low energy bulbs and especially LED can often have high frequency flicker rates brought on by the SMPSU in the bulb.

Can you explain how they 'synchronise', please? It's news to me.
 

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Posted : 28/09/2018 10:25 am
malcscott
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The cap on the loptx looks a little worse for wear? (220PF 8KV?)

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Posted : 28/09/2018 11:04 am
Focus Diode
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The microswitch was transplanted yesterday. This can only be done by removing the plate on the rear of the tuner as the switch is actually three separate parts.

All worked well for a little while before refusing to switch back to 405 from 625 with R123 sparking and emitting much smoke. It's badly blackened but still intact. Funnily how the fusible side didn't open, but the set was switched off immediately. Back to mechanical means of system switching for now.

Replacing some of the higher value resistors improved the width. Boost now around 610V with the control not at maximum. Decided to leave things well alone until the frame problems were sorted out. 

Replacing more resistors cured the bottom cramping but resulted in lack of overall height. Setting the control to maximum just about fills the screen. Its feed resistor has already been replaced.

This draws suspicion on R133, the boost feed 2W resistor. Looks to be in good condition and the original, yet I'm sure it's marked 470K. Service data suggests it should be 220K! I'll replace it next time.

Now to try the set on 625 VHF and UHF using the recently aquired modulator.

Ok, the contrast was set too high initially but was instantly reminded of the pulling on whites with occasional frame slip these sets are famous for. Surprigingly the sound seemed to be ok. As for tap sensitive flickering....

How on earth could Thorn produce their perfect dual standard model, the 900/950 series which gives equally superb results on both systems, then make such a mess with the 1400? I'm sure many service departments thought the same when they were new.

On the positive side the CRT is beginning to look much better than it did when I first got the set working.

Brian

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Topic starter Posted : 30/09/2018 10:24 am
Focus Diode
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Posted by: malcscott

The cap on the loptx looks a little worse for wear? (220PF 8KV?)

Hi Malc,

Not the first time I've seen a tubular disc on the Lopt tags. I'm sure another 16" example I saw was the same. They appear to be the original.

"Television" articles suggest they must be the round disc type. 

I think they are 160pF on the smaller screen sets, 220pF on the larger screen ones.

When I adapted the 960 portable to take a 1400 Lopt the nearest value I had was 180pF. It ran extremely hot after a very short time which was a cause for concern. I later removed a 160pF one from a 1500 Lopt which thankfully runs cool. Phew!

Cheers

Brian

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Topic starter Posted : 30/09/2018 10:43 am
MurphyV310
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Hi.

Well that reminds me to dig out my set, it has the maroon rexine cabinet but the mask is a bit tatty as is one knob, the picture is excellent as the tube. Again a bit of history as its the last 405 line only chassis as I believe the 981 is slightly later than the 980 series if I'm not mistaken.

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Posted : 01/10/2018 9:22 am
Focus Diode
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Hi Trevor,

Great to hear from you. You've been a big miss.

Did more work this morning. R133 was 220K after all but had doubled in value. Not having the correct 2W replacement I fitted 1W 100K and 150K resistors in series. Happily this put an end to the height problems.

Adjusting the linearity sleeve improved the stretched left side.

This is the result with the 405-line boost voltage set to 620V. The voltage shot up to 673V on a blank channel, this shouldn't happen surely hence why I left it at 620V when tuned in just incase. I have components to repair an EHT tray but not in the mood to do that at the moment!

The capacitor on the Lopt tags is just dirty. It visually looked sound when I scraped part of the dirt off.

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Topic starter Posted : 01/10/2018 12:01 pm
malcscott
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Plenty NOS 8kv disc caps here if you need one (or two) Malc.

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Posted : 01/10/2018 6:21 pm
Focus Diode
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Really very kind of you Malc seeing I've yet to send you anything for the pre-sets which I will do this week.

If you have a couple of 160pF types that would be great.

Cheers,

Brian

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Topic starter Posted : 02/10/2018 6:34 pm
malcscott
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Will check tomorrow, i think i have 180pf 8kv, Malc.

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Posted : 03/10/2018 12:10 am
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