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1975 Thorn 9000 & 1979 Thorn 9905 - SYCLOPS

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crustytv
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A Tale of Two Sets and me taking on "Old One Eye"

After having spent time in 1972 on the Ferguson 3714, the oldticktock time machine whisked me forward. This time up on the bench are another new to me offerings from Thorn, the 9K series chassis ( MultiBroadcast 7773 )and the 9905 series (DER 5111)

A little about the 9000

In 1975 Thorn once again startled the TV industry with the introduction of the 9000 series chassis with its Syclops combined chopper regulator/line output stage.

The 9000 used a parallel switched-mode power supply running synchronously with line. A conventional transistor line output stage except that it uses the power supply switching transistor to conduct the latter portion of scan with an efficiency diode conducting the first part. This was known as SYCLOPS (SYnchronous Converter and Line OutPut Stage)

Again Thorn seem to have put great thought into the layout for the service engineer. The entire chassis slides out on runners, the side panels swing out and up and the centre panel slides out even further. This gives optimum access to both side of the panels for component testing/removal.

The 9905 Chassis

Access Made easy for the Service Engineer

The Main TV up for repair 9000 Chassis - MultiBroadcast 773

This set is the main focus of my repair, a 1975 20" Thorn Television Rentals Model 773 badged for the Multibroadcast chain. Ultrasonic remote control (sequential channel change & sound mute only)however I don't have the remote. Nice touch is the nixie tube channel indication.

Now this set came from the same storage source as the 8500 and is equally as rusty, so I'm expecting many issues. Luckily for me Stan donated a DER 5111 to the cause which has a remarkably clean 9000 chassis, although he believes the CRT is tired and past it, but it certainly would offer a good set of panels or parts for the Multibroadcast.

The donor TV - DER 5111 - Or will this one be a potential repair Also, lets see......

As I mentioned this thread may turn into a two set resurrection we shall have to see whats what, I'm loathed to break up the DER.

With that in mind I want to see if the DER can be saved so I thought I would power it up first to see what it had to say for itself. I've read these sets just won't be happy on a variac or Lamp Limiter so it was just introduced to the mains. Powered up I heard the thump of the degauss and after a few seconds a loud crack, might have been a tant fart! any way seconds after that I was greeted with a bright red raster.

I noticed straight away we have no sound whatsoever, so the audio module might have been the source of the little bang. I fed in a pattern from the PM5515 and tuned up and down but to no avail. Whilst this was all happening the raster changed from Red to purple ( now the TV is getting really mad at being woken up).

I note the brightness and contrast controls do not have any effect on the raster.

At this point I decided to power down and before going much further ascertain the state of the A51-570X. My Leader manual states the base is an H-01 which translates to a JEDEC B12-262, which in turn translates to socket 11. I connected up, set the heater to 6.3, checked for shorts and leakage, there were none. Next was to set the G1 voltage to 45 then set the G2 cut-off for RGB. This is where it stopped, I cannot set G2 and when I check emission the meter deflects negative. So clearly the base I used is not correct. Options here are to get a socket, map the wiring and make up my own adapter, or borrow Malcs B&K to see whats the CRT state is.

One final observation the scan coils appear to be bonded to the CRT, in my newbness with this chassis it begs the question how on earth you do purity by withdrawing the coils to do the splodge. No doubt as time progress that question and its answer will be revealed to me.

So thats as far as I've got. I want to see the state of the two CRT's before proceeding too far.

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Posted : 23/08/2014 5:59 pm
sideband
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I never worked on SYCLOPS. I wonder if it's anything like IPSALO used by Salora. That stands for Integrated Power Supply And Line Output. Now those I have worked on.

 
Posted : 23/08/2014 6:45 pm
Red_to_Black
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IIRC, the 9000 used a single transistor to provide the chopping/driving action to both the power and LOP transformers, whereas the 9600 (110 degree tube) was more akin to the ipsalo circuit in that both these used seperate transistors for the line and power windings of the combined transformer in the case of the Ipsalo circuit, both driven at line rate of course. certain ITT sets of the era used a variation of a similar theme, as did at least one or two Grundig chassis, a couple of the Grundigs mentioned here used combined transformers as did the Ipsalo in the Salora design.
There were at least 3 versions of the Salora ipsalo design, two versions of Syclops from Thorn (9K and 9k6) also the one syclops from Thomson (TX80) , and one Ipsalo that I know of from Grundig

The ipsalo types had other subtle differences too and were a bit more sophisticated in operation than the simpler Thorn type.

The TX10 also used a similar-ish theme as it used a winding from the EHT/chopper transformer as the line driver transformer although was never described as Syclops as the lines (pardon the pun :bba ) were beginning to get blurred between the PSU proper just being synchronised at line rate and the seperate Lop stage.

I did at one time have the IPSALO training notes and in depth theory that I got from a kindly Granada engineer, now sadly long gone, the training notes that is! :bba

The Thomson designed TX80 resurrected the Syclops design in the early 90's from their earlier Thorn stable mates.

 
Posted : 23/08/2014 7:26 pm
Anonymous
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I don't think the scan coils are bonded to the tube on this chassis I think there are 3 wedges between the scan coils and the tube to set purity you remove them adjust the coils and reinsert the wedges but if they have not been interfered with they should be ok the purity and convergence are set by using the rings behind the scan coils .should only need altering if fitting a new tube,
Rob T

 
Posted : 23/08/2014 8:33 pm
crustytv
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I don't think the scan coils are bonded to the tube
Rob T

I could be wrong but they look pretty much bonded to me. I've checked and the glue is well and truly stuck to the CRT bowl and the plastic coil assembly. No matter, it was mainly a query should a CRT swap be necessary.

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Posted : 23/08/2014 10:26 pm
Jayceebee
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The 5111 is actually fitted with the 9900 chassis. Because of the saddle wound frame scan coils used on the A51-570X the frame deflection power requirements are less also raster correction is simplified, ISTR it only needs E-W correction N-S being unnecessary. Due the simplifications the raster correction daughter board is not fitted in the 9900.

Convergence and purity are preset from the factory on these CRTs and no adjustment should be necessary provided the ring magnets have not been disturbed. The scan coils aren't fully bonded as with the A51-161X and are detachable, the hot melt you see is mainly to keep rubber wedges in position which are inserted and adjusted in the factory for convergence correction at the edges of the screen.

The only PCB's which are interchangeable are the decoder, audio and power control daughter board, the CRT's are not interchangeable unfortunately.

John

John.

 
Posted : 23/08/2014 10:55 pm
Anonymous
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We used to buy reguned tubes for these sets that came minus the scan coils it was a bit of an ordeal to get the convergence right .
Rob T

 
Posted : 23/08/2014 11:04 pm
crustytv
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Hi John,

As ever your Thorn stable knowledge is invaluable. :aad

Well I never, so I have a Thorn 9900 :bba That's superb as I'm trying to collect Thorn examples so my stable just expanded. I wasn't aware of a 9900 I only knew of the 9600 & 9800

OK so these two sets will stand on their own as separate repairs, just need to decide which one to tackle first.

Now the dilemma, how to split up the thread :aaj Actually I might just change the title and deal with them in sequence of their release, 9000 (7773) first followed by the 9900 (5111)

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Posted : 23/08/2014 11:07 pm
Jayceebee
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Glad to be of help Chris. I may be wrong but also I don't think the 9900 was ever released on the UK retail market, never seen a Ferguson fitted with that chassis. As with all Thorn chassis serviceability in the field was important and the 9000 and 9900 had some nice touches, notice the extended pins on the frame board. The daughter boards can be removed from their normal position and mounted on the rear of the PCB print side up for fault finding.

I don't think it will take you long to get some pictures on it. Note that PIL CRTs don't have separate A1 pots, they are tied together in the gun assembly and brought out on one pin. The RGB output stages have two controls in each channel, the usual gain control and also a bias control to adjust the level of output.

John

John.

 
Posted : 24/08/2014 12:20 am
crustytv
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Glad to be of help Chris. I may be wrong but also I don't think the 9900 was ever released on the UK retail market

John

That might explain why I cannot locate any service data for the 9900.

I have a 9600 manual which looks very similar from the chassis photos within. I also have the 9800 covered in 79-80 R&TS. If they are of no use then I'm going to struggle as I do need to work from schematics.

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Posted : 24/08/2014 1:24 am
crustytv
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Hi Graham,

Thanks for the input, I had a feeling you might have some inside info.

I know all too well what goes into scanning and how time consuming it can be so don't worry, I can probably get by with the 9k data I have on various models. On the other hand if you do manage to scan it I would be eternally in your debt as I seriously doubt anyone local has this.

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Posted : 24/08/2014 1:35 pm
Anonymous
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Here are some pics (from the manual) of the 9000 chassis
I have a spare 9000 circuit if you want it
Rob T

 
Posted : 24/08/2014 2:09 pm
crustytv
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I have a spare 9000 circuit if you want it
Rob T

Yes please Rob :thumb

Any chance you could scan that manual as well ?

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Posted : 24/08/2014 2:11 pm
malcscott
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The 9000 used a A51-161X if i remember. These were RCA tubes which had the s/coils bonded to the crt bowl.

 
Posted : 24/08/2014 3:12 pm
Anonymous
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I have a spare 9000 circuit if you want it
Rob T

Yes please Rob :thumb

Any chance you could scan that manual as well ?

I must have the manual that goes with the circuit if I can find it you may have it ,I don't need 2
Rob T

 
Posted : 24/08/2014 3:57 pm
crustytv
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Looking at the DER (9900) I can hear the ghostly voice again, " Beware The Blue Tants". My god! the boards are flooded with them, I've never seen so many in one set. :ccf

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Posted : 24/08/2014 4:27 pm
crustytv
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So this thread log is complete for future searches, a look at the panels for the DER 5111

The 9905 Panels

Posted : 24/08/2014 7:17 pm
crustytv
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Thanks to Stan I have the start of the exact service info for the DER 5111, we now know its a 9905 series with both Graham and Stan's help.

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Posted : 24/08/2014 8:07 pm
crustytv
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Phase one of this thread
Work begins on the DER 5111

Investigating the faults on this set, as you recall from above first light was established with a Red raster which turned after a while to purple. With a colour bar signal fed in I'm getting nothing when tuning also no sound whatsoever.

This evening I powered on and was greeted with a White raster which I think went a bit Red finally settling on Purple, hard to tell as the set with all its panels open has to face away from the mirror and towards the window.

Anyway I checked the line & frame osc waveforms which are correct.

Next I went to check the R,G,B waveforms on the video board, these were not there! A voltage check shows R=1V, G=.4V and B=.8V. Checking back at pins 8,12 and 3 of the CRT base confirms the lack of voltage, we should have 215V. Also the grids (9) are at 79V and should be at 14-27V

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Posted : 25/08/2014 7:38 pm
Anonymous
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chris on your photo of the signal panel the luminance delay line is missing. unless its in a diferent place on that board
Rob T

 
Posted : 25/08/2014 7:53 pm
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