Dynatron can you identify this set? - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

dazzlevision · 28th Oct 2022, 12:22 pm

The plug goes into the top of the deflection coils.

Nuvistor · 28th Oct 2022, 1:00 pm

The blue caps have been around longer than the 80’s. Those controls came in a kit, knob, spire clip , wiper assy and the body. Check the contrast control, they went o/c, they would give a picture at one end of the travel but over contrasted.
Lots of memories fixing these, mainly stock faults, components on the van so most jobs sorted out quickly.

Electricdreams · 28th Oct 2022, 4:33 pm

Thanks Frank and Dazzle..

Couple more questions as I investigate the set. Found a knob for one of the adjustments. But also found a magnet and a missing valve.

The valve socket is the lower UHF tuner.. I dont have a copy of the schematics for this. Could anyone identify what valve it should be in there?

Is the Magnet supposed to be anywhere?

Electricdreams · 28th Oct 2022, 5:42 pm

Quote:

Originally Posted by Electricdreams

Thanks Frank and Dazzle..

Couple more questions as I investigate the set. Found a knob for one of the adjustments. But also found a magnet and a missing valve.

The valve socket is the lower UHF tuner.. I dont have a copy of the schematics for this. Could anyone identify what valve it should be in there?

Is the Magnet supposed to be anywhere?

I'm guessing it's a PC88.. The other is a PC86..

Nuvistor · 28th Oct 2022, 5:52 pm

The one near the aerial input is a PC88, I can’t see which it is. The knob will be from the broken control shown in earlier photos.

Heatercathodeshort · 28th Oct 2022, 6:01 pm

PC88 nearest the aerial input co-ax lead and socket, PC86 nearest the co-ax to the chassis/tuner. The magnet is probably part of the line linearity coil. I don't have a circuit to hand but I'm sure it has a coil assembly with magnet. Don't worry too much about tuner cleaning etc until you get something on the screen. You may break/disturb components and wiring that are then difficult to trace. J.

dazzlevision · 29th Oct 2022, 7:48 am

Here is where the magnet probably goes - on top of the audio output transformer at the bottom of the chassis.

If my memory is correct, the pincushion correction magnets mounted on the scan coils are of a different type and shape.

I agree that the missing valve on the UHF tuner is a PC88 - it's not as tall as the PC86 valve, which should be in the other valve holder.

dazzlevision · 29th Oct 2022, 7:55 am

Looking at the photos in post #20, I see the model/serial number on the small metal plate fixed between the two large printed circuit boards, says "TV74" and in dark blue ink on the metal shield for the mains dropper, it says "74 FW", which is shorthand for "Model TV74 with flywheel sync board fitted".

So, unless someone has swapped the chassis over, your set is actually a model TV74....??

Electricdreams · 29th Oct 2022, 8:08 am

Thanks Frank & John.

Let me take a photo of the scan coil mounts for you dazzle, hopefully it’s complete on that area.
Thank you for the photo of where the magnet should be. I’ll have a closer look (need coffee first!)

I hope the chassis hasn’t been swopped but I don’t know. It could be a later revised version?

Is this Dynatron a rare set?

Nuvistor · 29th Oct 2022, 9:13 am

Looking at the photo in post#20, there doesn’t seem to be a linearity coil on the sound output transformer, unless that also as fallen off.

Heatercathodeshort · 29th Oct 2022, 10:00 am

As Daz has mentioned it looks like the actual model number is TV74 F= flywheel, W = Walnut.
The presentation is probably rare but certainly not the guts.
Can you take a picture of the area around the sound output transformer. If you look at the chassis configuration you will see that removing two self tapping locking screws at the hinge point you can lower the chassis flat.

I enlarged the picture but could not make out the line lin coil. It is very unlikely that the chassis has been changed. The model number in blue on the screening can proves this.

From the PYE manual Aug 1964. The magnet is marked in RED. It is held in by the spring clip and when correctly set is sealed with paint to prevent movement. John.

dazzlevision · 29th Oct 2022, 10:21 am

Quote:

Originally Posted by Nuvistor

Looking at the photo in post#20, there doesn’t seem to be a linearity coil on the sound output transformer, unless that also as fallen off.

Yes, it does seem like that, but as the scan coils are of Ekco manufacture, I've only ever seen the line linearity magnet and coil mounted on the top of the AOPT. The Paxolin top of the AOPT does look to be of the larger size, to accommodate the LLC.

In earlier Pye/Invicta 11U chassis versions, with Elac brand scan coils, the LLC was taped to one of the Eat-West pincushion correction magnets.

A line linearity correction sleeve, which slides along the CRT's neck was never used in 11U series chassis.

AOPT = Audio Output Transformer
LLC = Line Linearity Control

dazzlevision · 29th Oct 2022, 11:26 am

In this photo, you can see the two solder tags that the LLC is connected to, plus the blue and pink wires and the 4.7kOhms (if my memory is correct - can't quite see all of the resistor's colour code bands) LLC damping resistor.

I expect you'll see that the tags, wires and resistor are present on your chassis.

Electricdreams · 29th Oct 2022, 1:59 pm

Hi Guys,

Thanks for the info, I went back and had a closer look at the sound output transformer, took a pic for you.

Some of the LOPT, dropper and of course under the flywheel board.

Is that plastic blue and white cap a new addition?

Not in any order fyi..

Electricdreams · 29th Oct 2022, 2:08 pm

I’ve fastened the speaker with a wire hanger. It looks like it was supposed to be fastened on with that!

Found a woodlouse and lots of spider nests.. I suspect this was stored in a garage for many years?

Can I warm up the LOPT while its in the chassis John? I’m on a look out for a bench power supply with mA limiter to dry it out.

What are these “wings” on the crt in photo 3?

Photo 4 is the flywheel valve. Im guessing something has happened to it to make the owners want to skip it?

Going back to the magnet on the sound transformer, I cannot find a clip to keep it on, I guess it’s lost forever, but the magnet I found on the sound transformer, I shouldn’t have picked it up I guess (d’oh!)

Nuvistor · 29th Oct 2022, 2:58 pm

The wings are pincushion correction magnets.
John and Dazzlevision will remember much more than I do.

dazzlevision · 29th Oct 2022, 4:56 pm

Quote:

Originally Posted by Electricdreams

What are these “wings” on the crt in photo 3?

Im guessing something has happened to it to make the owners want to skip it?

Those wings are pincushion distortion correction magnets.
Without them, any straight vertical straight lines in a TV picture would be barrel or pincushion shaped (i.e. not straight). They are on bendable brass (I think) arms, so they can be adjusted to give the straightest vertical lines in a picture (at each side of the screen).

The TV probably failed and was written off by a TV repairer in the distant past (I expect). Alternatively, they may have retired it when they bought a colour TV.

dazzlevision · 29th Oct 2022, 5:01 pm

Quote:

Originally Posted by Electricdreams

Hi Guys,

Thanks for the info, I went back and had a closer look at the sound output transformer, took a pic for you.

Some of the LOPT, dropper and of course under the flywheel board.

Is that plastic blue and white cap a new addition?

Not in any order fyi..

The LLC is definitely on top of the AOPT.

The blue and white plastic encapsulated capacitor on the line output transformer was made by Dubilier and was probably fitted in the 1970s, to replace a failed wax capacitor (this specific capacitor is known as the Boost HT reservoir capacitor). The Dubilier capacitor will almost certainly be faulty, as all of the wax dipped capacitors on the chassis will be.

You have got a lot of work ahead of you!

Heatercathodeshort · 29th Oct 2022, 5:14 pm

Yes you can leave the LOPT in position. Connect between the top cap of the PL36 and the top cap of the DY86/87.
You certainly have a lot of work ahead of you but don't disturb it too much at the start.
The broken controls are very common and the knob part can be replaced. There are different types, some without actual knobs, a flat item with just a screwdriver slot but they will fit the track and circlip. A request with a picture in the wanted section may come up with a couple. Keep the circlip and the wiper disc. John.

Electricdreams · 19th Nov 2022, 9:17 am

Good Morning!

I took the set out of the garage last night and did a test on the crt, I could not test anything and Bobbyball pointed out it has happened to him.
This morning I put in all the new valves that were missing, checked the condition of the power lead as I’ll just throw on a terminal block for now and got some replacement pots.

The new psu is now connected up to the lopt as suggested at 60ma. I will now let it cook for what is it again? 8 hours?

This evening or tomorrow morning I will attempt to see if there is light on the tube using my variac.

Will keep you posted

28th Oct 2022, 12:22 pm	#21
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,621	Re: Dynatron can you identify this set? The plug goes into the top of the deflection coils.

28th Oct 2022, 1:00 pm	#22
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Dynatron can you identify this set? The blue caps have been around longer than the 80’s. Those controls came in a kit, knob, spire clip , wiper assy and the body. Check the contrast control, they went o/c, they would give a picture at one end of the travel but over contrasted. Lots of memories fixing these, mainly stock faults, components on the van so most jobs sorted out quickly. __________________ Frank

28th Oct 2022, 4:33 pm	#23
Electricdreams Hexode Join Date: Mar 2008 Location: Manchester, UK. Posts: 478	Re: Dynatron can you identify this set? Thanks Frank and Dazzle.. Couple more questions as I investigate the set. Found a knob for one of the adjustments. But also found a magnet and a missing valve. The valve socket is the lower UHF tuner.. I dont have a copy of the schematics for this. Could anyone identify what valve it should be in there? Is the Magnet supposed to be anywhere? Attached Thumbnails __________________ What have you bought now??

28th Oct 2022, 5:52 pm	#25
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Dynatron can you identify this set? The one near the aerial input is a PC88, I can’t see which it is. The knob will be from the broken control shown in earlier photos. __________________ Frank

28th Oct 2022, 6:01 pm	#26
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Dynatron can you identify this set? PC88 nearest the aerial input co-ax lead and socket, PC86 nearest the co-ax to the chassis/tuner. The magnet is probably part of the line linearity coil. I don't have a circuit to hand but I'm sure it has a coil assembly with magnet. Don't worry too much about tuner cleaning etc until you get something on the screen. You may break/disturb components and wiring that are then difficult to trace. J. Last edited by Heatercathodeshort; 28th Oct 2022 at 6:13 pm.

29th Oct 2022, 7:48 am	#27
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,621	Re: Dynatron can you identify this set? Here is where the magnet probably goes - on top of the audio output transformer at the bottom of the chassis. If my memory is correct, the pincushion correction magnets mounted on the scan coils are of a different type and shape. I agree that the missing valve on the UHF tuner is a PC88 - it's not as tall as the PC86 valve, which should be in the other valve holder. Attached Thumbnails

29th Oct 2022, 7:55 am	#28
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,621	Re: Dynatron can you identify this set? Looking at the photos in post #20, I see the model/serial number on the small metal plate fixed between the two large printed circuit boards, says "TV74" and in dark blue ink on the metal shield for the mains dropper, it says "74 FW", which is shorthand for "Model TV74 with flywheel sync board fitted". So, unless someone has swapped the chassis over, your set is actually a model TV74....??

29th Oct 2022, 8:08 am	#29
Electricdreams Hexode Join Date: Mar 2008 Location: Manchester, UK. Posts: 478	Re: Dynatron can you identify this set? Thanks Frank & John. Let me take a photo of the scan coil mounts for you dazzle, hopefully it’s complete on that area. Thank you for the photo of where the magnet should be. I’ll have a closer look (need coffee first!) I hope the chassis hasn’t been swopped but I don’t know. It could be a later revised version? Is this Dynatron a rare set? __________________ What have you bought now??

29th Oct 2022, 9:13 am	#30
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Dynatron can you identify this set? Looking at the photo in post#20, there doesn’t seem to be a linearity coil on the sound output transformer, unless that also as fallen off. __________________ Frank

29th Oct 2022, 10:00 am	#31
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Dynatron can you identify this set? As Daz has mentioned it looks like the actual model number is TV74 F= flywheel, W = Walnut. The presentation is probably rare but certainly not the guts. Can you take a picture of the area around the sound output transformer. If you look at the chassis configuration you will see that removing two self tapping locking screws at the hinge point you can lower the chassis flat. I enlarged the picture but could not make out the line lin coil. It is very unlikely that the chassis has been changed. The model number in blue on the screening can proves this. From the PYE manual Aug 1964. The magnet is marked in RED. It is held in by the spring clip and when correctly set is sealed with paint to prevent movement. John. Attached Thumbnails Last edited by Heatercathodeshort; 29th Oct 2022 at 10:07 am.

29th Oct 2022, 11:26 am	#33
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,621	Re: Dynatron can you identify this set? In this photo, you can see the two solder tags that the LLC is connected to, plus the blue and pink wires and the 4.7kOhms (if my memory is correct - can't quite see all of the resistor's colour code bands) LLC damping resistor. I expect you'll see that the tags, wires and resistor are present on your chassis. Attached Thumbnails

29th Oct 2022, 1:59 pm	#34
Electricdreams Hexode Join Date: Mar 2008 Location: Manchester, UK. Posts: 478	Re: Dynatron can you identify this set? Hi Guys, Thanks for the info, I went back and had a closer look at the sound output transformer, took a pic for you. Some of the LOPT, dropper and of course under the flywheel board. Is that plastic blue and white cap a new addition? Not in any order fyi.. Attached Thumbnails __________________ What have you bought now??

29th Oct 2022, 2:08 pm	#35
Electricdreams Hexode Join Date: Mar 2008 Location: Manchester, UK. Posts: 478	Re: Dynatron can you identify this set? I’ve fastened the speaker with a wire hanger. It looks like it was supposed to be fastened on with that! Found a woodlouse and lots of spider nests.. I suspect this was stored in a garage for many years? Can I warm up the LOPT while its in the chassis John? I’m on a look out for a bench power supply with mA limiter to dry it out. What are these “wings” on the crt in photo 3? Photo 4 is the flywheel valve. Im guessing something has happened to it to make the owners want to skip it? Going back to the magnet on the sound transformer, I cannot find a clip to keep it on, I guess it’s lost forever, but the magnet I found on the sound transformer, I shouldn’t have picked it up I guess (d’oh!) Attached Thumbnails __________________ What have you bought now??

29th Oct 2022, 2:58 pm	#36
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Dynatron can you identify this set? The wings are pincushion correction magnets. John and Dazzlevision will remember much more than I do. __________________ Frank

29th Oct 2022, 5:14 pm	#39
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Dynatron can you identify this set? Yes you can leave the LOPT in position. Connect between the top cap of the PL36 and the top cap of the DY86/87. You certainly have a lot of work ahead of you but don't disturb it too much at the start. The broken controls are very common and the knob part can be replaced. There are different types, some without actual knobs, a flat item with just a screwdriver slot but they will fit the track and circlip. A request with a picture in the wanted section may come up with a couple. Keep the circlip and the wiper disc. John.

19th Nov 2022, 9:17 am	#40
Electricdreams Hexode Join Date: Mar 2008 Location: Manchester, UK. Posts: 478	Re: Dynatron can you identify this set? Good Morning! I took the set out of the garage last night and did a test on the crt, I could not test anything and Bobbyball pointed out it has happened to him. This morning I put in all the new valves that were missing, checked the condition of the power lead as I’ll just throw on a terminal block for now and got some replacement pots. The new psu is now connected up to the lopt as suggested at 60ma. I will now let it cook for what is it again? 8 hours? This evening or tomorrow morning I will attempt to see if there is light on the tube using my variac. Will keep you posted Attached Thumbnails __________________ What have you bought now??