Ferguson 998T

[mark pirate]

I was given this set a few up via my variac, after 20 mins it was on full mains, results were no audio, but a nice strong line whistle, but no raster.

I found the reason for no sound was an o/c output transformer, so a replacement was lashed up, now we have audio, so plugged in the aurora, but can't get the thing on the screen.

The problem maybe the retrofit ferguson tuner, there is life as the sound crackles when the turret is turned.


Mark

[ppppenguin]

Trader 1108 is claimed to be close. On your BVWS CDs.

Have you checked for EHT? The usual spark tests at the EY51 EHT rectifier anode and cathode.

[mark pirate]

Thanks Jeffrey, did look for the 998T, but will try your suggestion.
The EY51 has a cover over it, check for a spark, ican draw a small spark from the topcaps.

Mark

[Heatercathodeshort]

Hello Mark,
Without doubt one of the most reliable 405 receivers ever produced. Many of these ran for their entire service life without a single service call. Slight downpoint is the self oscillating line timebase that can be a bit sensitive but other than that, brilliant. Strangely enough I replaced the mains power lead to the 'museum' this morning and accidently left the mains isolator 'on'. When I returned this evening the 998T was happily playing away with some even older models. Took this picture a few moments ago. The picture is well focused and of good contrast. Not shown in pic!
Probably requires a recap of Dubiliar waxies. The 'coffin' LOPT may require drying out if when you get it working the width reduces after 30 mins. This is the receiver I carried out the 'saturation' tests with a while back now. Maybe still on archive. You may find a few circuit differences as the model progressed in production. regards, John.

[mark pirate]

Hi John, i can well believe these were a reliable set, this particular set looks to have been well used, it is fitted with a 'newvu' re-gunned crt, the only signs of repair are a couple of replacement caps below the chassis.

I wonder if it was taken out of use due to the o/c output tx?

I will take out the chassis today, and see if i can get some more life out of it, i had it running for over half an hour with no signs of distress, i noticed one end of the mains filter cap was cut, i can't remember powering it up before, but as this is usually the first thing i do, it is possible i have

The set has been stored in my garage for a couple of years, so i will take your advice re drying out the lopt

The cabinet is a bit rough, but no worm, so a bit of danish oil should smarten it up no end.

mark

[mark pirate]

A bit more progress, after seeing no heater in the ey51, but drawing a good spark from it's anode, i went about replacing it, not an easy task without removing the tube, as it is under the tube support.

This time, i got a better result, it was now less twitchy, and i now have test card 'c'.

The linearity is not good, but a recap should have this sorted, the tube also looks reasonable, the picture has now improved even more with the replacement of the py81 which was well tired.

Now i know it is a viable project, i will order some replacement caps!

Mark

[Heatercathodeshort]

You need to plug the Aurora into the Band 1 socket on the rear of the chassis. The tuner only operates on ITA and the aerial lead from the tuner is for Band 3 only...Got caught on this one myself. You have the later version with the octal socket for the tuner. The original circuit including the tuning wheel operates normally on Band 1. Band 3 is entirely separate. J.

[mark pirate]

Hi John, i did try the band1 tuner, but got nothing more than a few flashes on the screen while inserting the aerial plug, i did try the tuner in the band1 position, as i guess the wafer switch on the tuner switches back to band1, i also got nothing via the tuner wheel.

It is working fine via the band3 aerial socket, with the aurora on channel 8, so i will leave it at that for the time being.

It may benefit from a couple of new PY82's as they look to have lead a hard life,
I tried the set on the 220-230 tapping the improvement to the picture was noticeably better.

When i replace the caps (not many in this set) i will replace one at a time to notice the results, i have repaired quite a few sets, but never really gone down the tv restoration route as yet, this set looks to be a good starting point before i get stuck in to my more valuable sets!

Mark

[Boom]

I suspect the increase in performance as the voltage selector is dropped is probably due to low emisson valves.

[Heatercathodeshort]

Replacement of C23 .1uf [Newnes book] the sync coupling capacitor should straighten up the cogged effect on the test card and allow you to see what exactly is happening. The receiver should work very well on Band 1 and 3 and I can only think that the local oscillator has stopped the operation of Band 1, maybe something around the ECC81.
I have had all the tuning cores on the rotary tuning control become detached from their [brass?] wire supports due to being stuck in their formers but that is unlikely and can be set aside for the time being.
I can't make out if the fault is low R.F. gain or the video amplifier has bottomed out. Replacement of all the waxies in the frame timebase should sort out picture shape. Nice clean example. I can pull mine apart if we need to, takes only a minute to dismantle. Regards, John.

[mark pirate]

Hi John, you are spot on, i have had another look at the band 1 tuner, one of the cores has become detached, this will be repaired (hopefully) when i start replacing the caps.

I have a nos ecc81, so will see if that improves things.

I have now fitted the replacement audio o/p tx, luckily one of the original holes on the chassis is slotted, so the replacement went straight in

I am getting to like this little set, it is very easy to work on, it is now back in it's cabinet, all cap replacement can be done easily from underneath, unfortunately the bottom panel is missing, but i can easily make one, the back also needs repair at the top, but this should also be easy.

Mark

[Heatercathodeshort]

They get a bit tender with age. Araldite is superb for this and a slight rub down with fine abrasive paper will ensure the cores slide easily in the formers. Probably worth a blob on the other two. More than likely it's the oscillator coil that has become detached. Make a note of the settings with Tipex. Not critical but saves retuning the bandpass and R.F. coils. It's difficult to stop the oscillator on the 998T! It may well be running but just off tune. They are a really simple set, what would have been called 'an entry model' in today's nonsense. Probably the last 12" table model. Worth having a rough check on the anode voltages on the ECC81 to make sure the supply is being switched. I think the oscillator voltage is removed on Band 3. [circuit not to hand at moment] J.

[mark pirate]

I have got this set back on the bench replaced a few caps it is certainly better but the frame hold is very touchy and after a minute or so it drifts again am working without service info as rader 1108 has to many differences to my set any ideas what to go for to sort this would most welcome.

Mark

[mark pirate]

I have replaced 4 more caps, and the set is nearly there, still a bit to do, but it's looking positive.

Mark

[Heatercathodeshort]

Looking good Mark. They really are a super set. The appearance is a bit boring so no chance of it becoming a collectors cult item thankfully. Incredibly reliable due to the simple stripped out circuit. The frame timebase caps will all need to be replaced with best quality components. The self oscillating line output stage can be slightly touchy and tends to verge towards low frequency rather than high but once sorted will remain stable.You can then put the back on it and use it for another 50 years! Regards, John.

[Mike Phelan]

Brings back memories. We had a few of these out on rental and not too many service calls at all.

Very reliable and very easy to work on. Pye V4 eat your heart out!

Your set looks nice and clean and the CRT has plenty of life in it.

[mark pirate]

The photos make the picture look better than it is, but it is coming along, i have a real task to get the picture position & focus right at the same time, everything seems to interact with each other, particularly the brightness & contrast controls, i need to sort out the band 1 tuner & recap the receiver section, as i can either have sound or vision, but not both together!

Mark

[mark pirate]

A few more questions, i am replacing a few more caps, but cannot identify this particular mouldseal, as usual it is falling apart (see photo 4).

I want to repair the band 1 tuner, as can be seen in photo 2, it has parted company with it's slug, below the chassis it looks like the aerial feeder cable has been cut off, (see photo 3) which is why i could not get a signal through it!
Is it worth repairing & bypassing the band 3 tuner, or just use via the band 3 tuner?

I have also found that the paxolin valve holder for one of the PY82's is tracking & needs replacing, luckily i have a scrap radiogram chassis that can give me a valveholder.

I am out of stock of a couple of caps, but have replaced all the 0.1's And 3 electrolitics (see photo 1)

Mark