EM 80 in Wega 201 radio. - UK Vintage Radio Repair and Restoration Discussion Forum

longneck90 · 25th May 2018, 6:06 pm

Hello to everyone. I am hoping that some of the Forum mmbers might be able to advise me about the EM 80 in this radio. It doesn't work, and I am wondering (because the service diagram does not agree with the the details of the valve pinout) whether there may have have been a different 'Magic eye' installed in this radio. The first picture is of the EM 80s base details, and the second is the details of the actual valve installed in radio. The valve base in radio has no connections to pin 2 or pin 8. Thanks in advance. All the best. John.

vinrads · 26th May 2018, 8:00 am

Hi I am not sure what the problem is , the first diagram is correct for the EM80 you need to fit the 470k resistor between pins 7 and 9 ht goes to pin 9 earth pin 2 , 4 and 5 heaters does not matter which way round , pin 1 grid , have a go and let us know , Mick.

ms660 · 26th May 2018, 9:11 am

Only one I could find that might fit that wiring is the EMM801...…?

Lawrence.

Cobaltblue · 26th May 2018, 9:46 am

I wondered if it's been wired for a 6E2

http://www.r-type.org/exhib/abn0024.htm

Cheers

Mike T

ms660 · 26th May 2018, 9:53 am

I missed that one.

Lawrence.

longneck90 · 26th May 2018, 3:13 pm

Hello to all, and thanks for all the advice. Unfortunately, my explanations of what the photos of the drawings depict, are a bit fuzzy. I'll try to do better now. Photo (1) in this post, is a copy of the 'Radio Museum' EM 80 pinout and connecting circuit. Photo (2) is my drawing of the connections to the valve base presently in the radio, and supposedly meant to accomodate a EM 80. As will be noticed, there is 275 volts on Pin 2, Which, according to EM80 drawing, should be connected to earth. Also, there is 274 volts on Pin 8, even though there is no connection to it. There is 279 volts on Pin 6, then via a 500K resistor to Pin 9, which has 17 volts, when, for an EM 80 should have 250 volts. Photo (3) shows the diagram of EM 80, taken from the Wega 201 circuit diagram. As the connections to the EM 80 ? valve base have never been disturbed, I am reluctant to interfere with them unless as a last resort. Thanks again to all. All the best. John.

Leon Crampin · 26th May 2018, 4:18 pm

Your set is not wired to suit an EM80 (or EM81).

The connections you show for the set are correct for an EM84 or EM85. Nearly all of the B9A based eyes have "IC" (internal connection) pins which are in fact connected to the target. This is to provide mechanical support for the structure of the valve - the target is heavy sheet metal.

You can either fit an EM84 or 85 or rewire the base for an EM80 or 81. The displays are all different in that the EM85 has a small fan, and the EM80 fan works in the opposite sense to the others (a strong signal opens the eye). The EM84 is a bar type display.

If you operate the set with an EM80 or 81 fitted as it is presently wired, you may short the HT supply. The internal connections to these valves explain why you get 275V on disconnected pins.

Leon.

paulsherwin · 26th May 2018, 4:31 pm

EM84: http://www.r-type.org/exhib/aaa0079.htm
EM85: http://www.r-type.org/exhib/aag0036.htm

longneck90 · 26th May 2018, 4:42 pm

Hello to all, and thanks to Leon and to Paul. What you say Leon, makes sense. I'll try and locate an EM 84 or EM85. Then I'll report back. Thanks to all. All the best. John.

Chris55000 · 26th May 2018, 6:18 pm

Hi!

EM84/EM85 Summary:-

Vh 6.3V
Ih 210mA

Vt 250V
Vg -22V for closed shadow
Ra 470K

pin 1 g,
pin 2 i.c.,
pin 3 k,g',
pin 4 h,
pin 5 h,
pin 6 t,
pin 7 d,
pin 8 i.c.,
pin 9 a

d = deflector, t = target-anode.

NB! If the front panel aperture is the larger oval/semi-oval type like the EM80, then you'll need an EM85 or Cossor 65ME, and it's dreadfully scarce and expensive! Electrically it's identical to the EM84 in basing/characteristics!

If you can't get a lot of a.g.c. voltage, indicated by little movement of the eye even on strong signals, you can get a more sensitive indication by adding a resistor of about 33-100k in series with the target-anode connection to pin 6, or, if you're good at making panel escutcheons, etc., to mask the aperture to EM84/EM87 size, you can plug in an EM87 which is more sensitive and closes at -10V!

Chris Williams

longneck90 · 8th Jun 2018, 9:27 pm

Hello to all. I am sorry it has taken so long to report what's what with Wega 'Magic Eye'. I was waiting for something positive to report, but that didn't happen. Thanks to everyone for all the help and advice, which is truly appreciated, including all the trouble that Kevin (brightsparkey) went to, putting the sections of the Wega 201 circuit diagram together, which better enabled me to try and work out the problem. Sadly, I have to report failure. I have changed, or temporarily substituted, all the relevant resistors and capacitors. Ie. C33, R17, R18. C37, C38, R20, R21. R22. R12, R13., and C26. Nothing i have done makes the slightest difference to the 'Magic eye'. I have attached the oscilloscope to Pin 1, 6E1P, and the pattern on the scope screen moves in sympathy with what is being broadcast on the radio. However, after removing some capacitors and resistors in extremely difficult places, and replacing them, and then to find that the radio is still working well, I am reluctant to go further. (Ie. When its not broke, don't fix it) Therefore, I intend to return the little radio to it's cabinet, and leave it there until I know a bit more. Thanks to all, and all the best. John.

kalee20 · 9th Jun 2018, 6:39 am

Can you put up a photo of what the eye looks like when powered-up? Seeing this, we can work out whether it is fully open or fully closed, at least.

Magic eyes are basically simple in operation, once the ideas are grasped.

longneck90 · 9th Jun 2018, 12:27 pm

Hello to all, and to kalee20; Thanks for your suggestion for a photo. It is very sunny here today, (for photo of 'Magic Eye') but hopefully, these photos are OK, All the best. John.

ms660 · 9th Jun 2018, 12:35 pm

Looks like no signal voltage at the grid, as has been said before, tune into a strong station and measure the grid voltage, if it's not -ve then follow the grid feed back to the detector, at some point the voltage should be -ve.

Lawrence.

longneck90 · 9th Jun 2018, 2:39 pm

Hello to all, and thanks Lawrence. I feel pretty stupid asking this question, which is; How can I tell if a voltage is negative? None of the multimeters I have, will actually do this. (as far as I can tell) All the best. John.

Sideband · 9th Jun 2018, 3:11 pm

If you are using a digital meter it will tell you directly with a clear - (minus) before the number (example -7.6). A positive voltage will generally just show (for example) 7.6. If you are using an analogue meter, the pointer will try to move backwards....all you do is reverse the leads but you are then reading a negative voltage.

ms660 · 9th Jun 2018, 3:25 pm

If it's a DMM then as an example 1.5 volts positive should be displayed similar to this: 1.50

If it was negative 1.5 volts it should be displayed similar to this: -1.50

If your not sure then make sure the black meter lead is plugged into the common socket and the red meter lead is plugged into the voltage socket, connect the red probe to chassis and measure with the black probe, a negative voltage with respect to chassis would then be displayed similar to this (negative 1.5 volts example) 1.50

With the magic eye, more -ve volts on the grid means more deflection, 0 volts on the grid means minimum deflection.

You can see this for yourself in the EM80 valve data here:

http://www.r-type.org/pdfs/em80.pdf

Scroll down to the graph, it plots the illuminated display angle against the grid voltage, the horizontal axis at the bottom is the grid voltage, the vertical axis to the right is the illumination angle, you will see that the greater the -ve grid voltage the greater will be the illumination angle.

Both the AM and FM detectors produce a -ve voltage that's proportional to the signal strength, it's that -ve voltage that controls the angle of illumination in the magic eye.

EDIT: Post crossed.

Lawrence.

longneck90 · 9th Jun 2018, 6:15 pm

Hello to all, and thanks to Lawrence and Sideband for your advice etc. I have just tried my 3 multimeters, and none of them give any indication that a negative voltage is being measured. However, just by chance, I have found my 'moving coil' meter. There is no problem with it, as I can easily read the negative voltages. I am presently following the negative voltage (- 1 Volt) back from Pin !, EM 80 ?. The photo shows what I presumed was capacitor C 27, which is supposed to be 5n. This component is marked 1M, with an Ohms sign following the 1M. It has a white spot near one end. It looks more like a capacitor, so I was hoping some of the Forum members might recognise what it is. All the best. John.

ms660 · 9th Jun 2018, 6:20 pm

If it was connected to pin 9 of the EF89 it might be R10.

Using an analogue meter on a low range to measure the magic eye grid voltage will seriously affect the grid voltage you're trying to measure...….Impedance.

Lawrence.

kalee20 · 9th Jun 2018, 9:56 pm

Definitely nothing negative on the grid.

Easy way to show it works, get a 9V battery, connect the positive to pin 2 (cathode) and negative to pin 1 (grid). You should see the display open pretty wide.

You won't need to disconnect anything for this, though if the radio is playing, you'll probably find it mutes while the battery is connected.

25th May 2018, 6:06 pm	#1
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	EM 80 in Wega 201 radio. Hello to everyone. I am hoping that some of the Forum mmbers might be able to advise me about the EM 80 in this radio. It doesn't work, and I am wondering (because the service diagram does not agree with the the details of the valve pinout) whether there may have have been a different 'Magic eye' installed in this radio. The first picture is of the EM 80s base details, and the second is the details of the actual valve installed in radio. The valve base in radio has no connections to pin 2 or pin 8. Thanks in advance. All the best. John. Attached Thumbnails

26th May 2018, 8:00 am	#2
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,754	Re: EM 80 in Wega 201 radio. Hi I am not sure what the problem is , the first diagram is correct for the EM80 you need to fit the 470k resistor between pins 7 and 9 ht goes to pin 9 earth pin 2 , 4 and 5 heaters does not matter which way round , pin 1 grid , have a go and let us know , Mick.

26th May 2018, 9:11 am	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: EM 80 in Wega 201 radio. Only one I could find that might fit that wiring is the EMM801...…? Lawrence.

26th May 2018, 9:46 am	#4
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,857	Re: EM 80 in Wega 201 radio. I wondered if it's been wired for a 6E2 http://www.r-type.org/exhib/abn0024.htm Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

26th May 2018, 9:53 am	#5
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: EM 80 in Wega 201 radio. I missed that one. Lawrence.

26th May 2018, 3:13 pm	#6
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	Re: EM 80 in Wega 201 radio. Hello to all, and thanks for all the advice. Unfortunately, my explanations of what the photos of the drawings depict, are a bit fuzzy. I'll try to do better now. Photo (1) in this post, is a copy of the 'Radio Museum' EM 80 pinout and connecting circuit. Photo (2) is my drawing of the connections to the valve base presently in the radio, and supposedly meant to accomodate a EM 80. As will be noticed, there is 275 volts on Pin 2, Which, according to EM80 drawing, should be connected to earth. Also, there is 274 volts on Pin 8, even though there is no connection to it. There is 279 volts on Pin 6, then via a 500K resistor to Pin 9, which has 17 volts, when, for an EM 80 should have 250 volts. Photo (3) shows the diagram of EM 80, taken from the Wega 201 circuit diagram. As the connections to the EM 80 ? valve base have never been disturbed, I am reluctant to interfere with them unless as a last resort. Thanks again to all. All the best. John. Attached Thumbnails

26th May 2018, 4:18 pm	#7
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,870	Re: EM 80 in Wega 201 radio. Your set is not wired to suit an EM80 (or EM81). The connections you show for the set are correct for an EM84 or EM85. Nearly all of the B9A based eyes have "IC" (internal connection) pins which are in fact connected to the target. This is to provide mechanical support for the structure of the valve - the target is heavy sheet metal. You can either fit an EM84 or 85 or rewire the base for an EM80 or 81. The displays are all different in that the EM85 has a small fan, and the EM80 fan works in the opposite sense to the others (a strong signal opens the eye). The EM84 is a bar type display. If you operate the set with an EM80 or 81 fitted as it is presently wired, you may short the HT supply. The internal connections to these valves explain why you get 275V on disconnected pins. Leon.

26th May 2018, 4:31 pm	#8
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: EM 80 in Wega 201 radio. EM84: http://www.r-type.org/exhib/aaa0079.htm EM85: http://www.r-type.org/exhib/aag0036.htm

26th May 2018, 4:42 pm	#9
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	Re: EM 80 in Wega 201 radio. Hello to all, and thanks to Leon and to Paul. What you say Leon, makes sense. I'll try and locate an EM 84 or EM85. Then I'll report back. Thanks to all. All the best. John.

26th May 2018, 6:18 pm	#10
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,864	Re: EM 80 in Wega 201 radio. Hi! EM84/EM85 Summary:- Vh 6.3V Ih 210mA Vt 250V Vg -22V for closed shadow Ra 470K pin 1 g, pin 2 i.c., pin 3 k,g', pin 4 h, pin 5 h, pin 6 t, pin 7 d, pin 8 i.c., pin 9 a d = deflector, t = target-anode. NB! If the front panel aperture is the larger oval/semi-oval type like the EM80, then you'll need an EM85 or Cossor 65ME, and it's dreadfully scarce and expensive! Electrically it's identical to the EM84 in basing/characteristics! If you can't get a lot of a.g.c. voltage, indicated by little movement of the eye even on strong signals, you can get a more sensitive indication by adding a resistor of about 33-100k in series with the target-anode connection to pin 6, or, if you're good at making panel escutcheons, etc., to mask the aperture to EM84/EM87 size, you can plug in an EM87 which is more sensitive and closes at -10V! Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! Last edited by Chris55000; 26th May 2018 at 6:28 pm.

8th Jun 2018, 9:27 pm	#11
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	Re: EM 80 in Wega 201 radio. Hello to all. I am sorry it has taken so long to report what's what with Wega 'Magic Eye'. I was waiting for something positive to report, but that didn't happen. Thanks to everyone for all the help and advice, which is truly appreciated, including all the trouble that Kevin (brightsparkey) went to, putting the sections of the Wega 201 circuit diagram together, which better enabled me to try and work out the problem. Sadly, I have to report failure. I have changed, or temporarily substituted, all the relevant resistors and capacitors. Ie. C33, R17, R18. C37, C38, R20, R21. R22. R12, R13., and C26. Nothing i have done makes the slightest difference to the 'Magic eye'. I have attached the oscilloscope to Pin 1, 6E1P, and the pattern on the scope screen moves in sympathy with what is being broadcast on the radio. However, after removing some capacitors and resistors in extremely difficult places, and replacing them, and then to find that the radio is still working well, I am reluctant to go further. (Ie. When its not broke, don't fix it) Therefore, I intend to return the little radio to it's cabinet, and leave it there until I know a bit more. Thanks to all, and all the best. John.

9th Jun 2018, 6:39 am	#12
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,077	Re: EM 80 in Wega 201 radio. Can you put up a photo of what the eye looks like when powered-up? Seeing this, we can work out whether it is fully open or fully closed, at least. Magic eyes are basically simple in operation, once the ideas are grasped.

9th Jun 2018, 12:27 pm	#13
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	Re: EM 80 in Wega 201 radio. Hello to all, and to kalee20; Thanks for your suggestion for a photo. It is very sunny here today, (for photo of 'Magic Eye') but hopefully, these photos are OK, All the best. John. Attached Thumbnails

9th Jun 2018, 12:35 pm	#14
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: EM 80 in Wega 201 radio. Looks like no signal voltage at the grid, as has been said before, tune into a strong station and measure the grid voltage, if it's not -ve then follow the grid feed back to the detector, at some point the voltage should be -ve. Lawrence.

9th Jun 2018, 2:39 pm	#15
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	Re: EM 80 in Wega 201 radio. Hello to all, and thanks Lawrence. I feel pretty stupid asking this question, which is; How can I tell if a voltage is negative? None of the multimeters I have, will actually do this. (as far as I can tell) All the best. John.

9th Jun 2018, 3:11 pm	#16
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,567	Re: EM 80 in Wega 201 radio. If you are using a digital meter it will tell you directly with a clear - (minus) before the number (example -7.6). A positive voltage will generally just show (for example) 7.6. If you are using an analogue meter, the pointer will try to move backwards....all you do is reverse the leads but you are then reading a negative voltage. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

9th Jun 2018, 3:25 pm	#17
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: EM 80 in Wega 201 radio. If it's a DMM then as an example 1.5 volts positive should be displayed similar to this: 1.50 If it was negative 1.5 volts it should be displayed similar to this: -1.50 If your not sure then make sure the black meter lead is plugged into the common socket and the red meter lead is plugged into the voltage socket, connect the red probe to chassis and measure with the black probe, a negative voltage with respect to chassis would then be displayed similar to this (negative 1.5 volts example) 1.50 With the magic eye, more -ve volts on the grid means more deflection, 0 volts on the grid means minimum deflection. You can see this for yourself in the EM80 valve data here: http://www.r-type.org/pdfs/em80.pdf Scroll down to the graph, it plots the illuminated display angle against the grid voltage, the horizontal axis at the bottom is the grid voltage, the vertical axis to the right is the illumination angle, you will see that the greater the -ve grid voltage the greater will be the illumination angle. Both the AM and FM detectors produce a -ve voltage that's proportional to the signal strength, it's that -ve voltage that controls the angle of illumination in the magic eye. EDIT: Post crossed. Lawrence.

9th Jun 2018, 6:15 pm	#18
longneck90 Hexode Join Date: Sep 2013 Location: Wembley, London, UK. Posts: 395	Re: EM 80 in Wega 201 radio. Hello to all, and thanks to Lawrence and Sideband for your advice etc. I have just tried my 3 multimeters, and none of them give any indication that a negative voltage is being measured. However, just by chance, I have found my 'moving coil' meter. There is no problem with it, as I can easily read the negative voltages. I am presently following the negative voltage (- 1 Volt) back from Pin !, EM 80 ?. The photo shows what I presumed was capacitor C 27, which is supposed to be 5n. This component is marked 1M, with an Ohms sign following the 1M. It has a white spot near one end. It looks more like a capacitor, so I was hoping some of the Forum members might recognise what it is. All the best. John. Attached Thumbnails

9th Jun 2018, 6:20 pm	#19
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: EM 80 in Wega 201 radio. If it was connected to pin 9 of the EF89 it might be R10. Using an analogue meter on a low range to measure the magic eye grid voltage will seriously affect the grid voltage you're trying to measure...….Impedance. Lawrence. Last edited by ms660; 9th Jun 2018 at 6:31 pm.

9th Jun 2018, 9:56 pm	#20
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,077	Re: EM 80 in Wega 201 radio. Definitely nothing negative on the grid. Easy way to show it works, get a 9V battery, connect the positive to pin 2 (cathode) and negative to pin 1 (grid). You should see the display open pretty wide. You won't need to disconnect anything for this, though if the radio is playing, you'll probably find it mutes while the battery is connected.