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Ferguson 3173

Pre War 240/405, Post War 405 Line, B&W Dual Standard, Colour Dual Standard, B&W S/S 625, Colour S/S 625 line, Hybrids. Standards converters & modulators, video recorders.
 
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Ferguson 3173

Post by The_Teleman » Thu Jul 28, 2016 2:54 pm

At a bit of a loose end today so thought I would have a look at this set
I've been thinking of offering this set for exchange for a PYE set of equivalent age/ size
Without even touching it .
It's a Ferguson 3713 fitted with the Thorn 8500 series chassis
On removing the back cover I was pleasantly surprised on how clean & almost like new condition it is , no years of dust ,no nicotine stained plastic & no corrosion well the tiniest bit
It looked like it had just been taken out of the box
It makes you feel like just plugging it in & tuning in
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The Ferguson 3713

 
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Re: Ferguson 3173

Post by The_Teleman » Thu Jul 28, 2016 2:58 pm

The inside of the set
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Re: Ferguson 3173

Post by The_Teleman » Thu Jul 28, 2016 3:02 pm

Then I spotted this :ccb
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Looks like that needs replacing

 
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Re: Ferguson 3173

Post by malcscott » Thu Jul 28, 2016 3:27 pm

What value?

 
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Re: Ferguson 3173

Post by The_Teleman » Thu Jul 28, 2016 3:39 pm

Hi Malc,
There are 2 green smoothing caps that have leaked
The one you can see is a 700uf 250 volt
The one under the dropper is a 400uf 350 volt
I have 2 600uf caps & was wondering if I should give them a try

Chris

 
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Re: Ferguson 3173

Post by malcscott » Thu Jul 28, 2016 3:44 pm

They should work fine. They will need to be re-formed before using them if they are NOS ones, Malc.

 
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Re: Ferguson 3173

Post by PYE625 » Thu Jul 28, 2016 5:57 pm

A good one Chris, looks to be a nice set :aad

 
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Re: Ferguson 3173

Post by Till Eulenspiegel » Thu Jul 28, 2016 9:04 pm

I've still got 8000/8500 power supply elcos in stock, real 1970s stuff, will need reforming before you use them.

Till Eulenspiegel.

 
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Re: Ferguson 3173

Post by The_Teleman » Fri Jul 29, 2016 4:51 pm

Having reformed 2 nos 600 uf smoothing capacitors & fitted them
I then powered up but the cut out popped out immediately
Not finding any shorts around the power supply area , l decided to have a closer look at
The line output transistor , not short , but it was leaky from collector to emitter
Fitting a new one & replacing the 002 uf 2kv on the same heat sink
I then had EHT but smoke :stm: . R402 has burned up not having a manual for this set I'm not totally sure what it feeds .
It looks like it supplies w403 diode
Can anyone help ?

Chris

 
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Re: Ferguson 3173

Post by CTV » Fri Jul 29, 2016 5:02 pm

aa.jpg
.

 
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Re: Ferguson 3173

Post by The_Teleman » Fri Jul 29, 2016 5:15 pm

Thanks Chris :thumb

 
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Re: Ferguson 3173

Post by Cathovisor » Fri Jul 29, 2016 5:47 pm

C401 dead...?

 
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Re: Ferguson 3173

Post by CTV » Fri Jul 29, 2016 5:57 pm

aaa.jpg

Not related to the current fault, I've also read that on the same panel you should check R404 33KR 1W as it frequently fails. It feeds line pulse to the decoder. Apparently later boards had a wire-wound resistor in this position.

Don't forget all the 8000 stock faults apply to the 8500 of which your current fault was included http://www.radios-tv.co.uk/brc-8000-stock-faults/

 
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Re: Ferguson 3173

Post by The_Teleman » Fri Jul 29, 2016 7:24 pm

Replace R402 & W403 as a precaution but the fault was traced to the red A1 pot had tracked across the back
Now I have a raster but out of focus , looks like the focus unit has failed
Or the EHT rectifier tray
:zx:

Chris

 
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Re: Ferguson 3173

Post by CTV » Fri Jul 29, 2016 7:29 pm

If its the EHT tray I have plenty in stock, if you need one you're welcome. The focus units on these sets are dire after all these years, "Thick film" types.

I had the same defocussed fault with my focus unit, had to buy a new one.

Image
Image

 
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Re: Ferguson 3173

Post by slidertogrid » Fri Jul 29, 2016 7:35 pm

The tray is a common cause of focus problems on the 8500 it was the first part that failed in my parents set it was about 4 years old at the time.
I had to change the LT smoothers last year as one suddenly went o/c while I was watching it.
That looks like a nice clean low hours set. I have yet to have a look at the one I got from Neil but somehow I don't think it will be as nice as yours inside!
Rich.

 
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Re: Ferguson 3173

Post by The_Teleman » Fri Jul 29, 2016 7:39 pm

Is the focus unit a standard type or a special to this set
The reason I ask this is I tried a focus unit but made no difference

Chris

 
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Re: Ferguson 3173

Post by CTV » Fri Jul 29, 2016 7:44 pm

I had a load of NOS focus units in stock that looked identical but failed to work, this was due to them having varying resistive properties. The ones I had were not compatible with the 8500 despite outwardly looking the same.

Beware all focus pots that fit this set despite appearance, are not equal.

I had to buy the specific one for the 8500. Unfortunately they are now out of stock from where I bought them. I will see if I kept the data for it.

Edit: Also check the focus spark gap on the crt base it may be leaky I had that exact problem on another, using the megger I found it.

 
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Re: Ferguson 3173

Post by CTV » Fri Jul 29, 2016 7:46 pm

The 8500 Focus unit must read as follows:-

Between the left hand pin (+) and the start of the wiper track its needs to measure 17.6 M ohm

The wiper track itself should measure 30 M ohm

Between the end of the wiper track and the right hand pin (E) it should measure 26 M ohm

 
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Re: Ferguson 3173

Post by The_Teleman » Fri Jul 29, 2016 7:58 pm

Thanks for the info Chris

I'll give it a go with some measurements

Chris

 
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Re: Ferguson 3173

Post by The_Teleman » Sat Jul 30, 2016 12:33 pm

Looks like I have a duff focus pot
But still not sure about the EHT tray because the picture looks lacking in something
So bad focus ,no red drive , no colour & these are only the faults I can see so far
These sets don't seem to far well with storage
While there doesn't seem to be any evidence of damp it's becoming clear that
It hasn't been stored in dry conditions probably been in a garage for years
But is so clean inside

Chris ( crusty tv ) can I take you up on your offer of an EHT tray ?
Just In case I'm barkin up the wrong tree here with the focus fault

Chris

 
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Re: Ferguson 3173

Post by CTV » Sat Jul 30, 2016 12:42 pm

The_Teleman wrote:Chris ( crusty tv ) can I take you up on your offer of an EHT tray ?
Just In case I'm barkin up the wrong tree here with the focus fault

Chris

Hi Chris,

I checked the box and what I thought contained about x20 8500 EHT trays, contained all 8000 EHT trays. Flamin typical as I have 8500 and 8800 sets and not one 8000 TV. :bbd I don't believe they are interchangeable due to the different focus arrangements on the 8000 compared the 8500/8800. I will have to do some reading on the service data to be sure.

8keht.jpg

 
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Re: Ferguson 3173

Post by CTV » Sat Jul 30, 2016 1:02 pm

As suspected.

doh.jpg

The Thorn 8000 series line output transformer develops the full EHT AC voltage, hence it does not require a tripler. The 8000 EHT trays are rectifiers. The difference between the 8000 tray and the 8500/ 8800 tray is that the latter includes a resistor which feeds the focus pot, the former does not.

Did you measure the thick film units resistance what were you findings? Did they differ with regards to the expected values I gave above? I would lay money on it being the Focus control. I wonder if there is anyway you could lash up some suitable rated stand alone resistors to mimic a mid point setting to prove the point.

As for storage of these sets, mine came from being stored in a tin shed and although dry the humidity factor played havoc with transistors, IC's and almost all pre-sets. Legs of transistors and IC's were rotted.

 
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Re: Ferguson 3173

Post by The_Teleman » Sat Jul 30, 2016 1:34 pm

Hi Chris

I did measures the focus pot
Between F & + I got 30 meg and between F & E I got open circuit
Which would meet the focus is floating
But the focus voltage is still low
I removed the spark gap & replaced the 100k & the cap on the CRT base
But still no joy

Chris

 
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Re: Ferguson 3173

Post by The_Teleman » Sat Jul 30, 2016 4:03 pm

Well the focus is still poor but taking apart the focus unit & cleaning it did make a
slight difference
The lack of red is due to no drive to the red output transistor , looks like it's down to the
Mc1327 Ic being faulty
Another fault is the whole picture looks week as if the CRT is poor , now I know the CRT is good as all guns read over 90% on my CRT tester
I'm thinking lack of EHT & that would count for the poor focus too
I've managed to order a EHT tray & a mc1327
Then there is still the no colour to sort out
Now I know why I don't like thorn sets .
Give me a good old PYE any day

Chris

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