Alignment device - UK Vintage Radio Repair and Restoration Discussion Forum

reeltoreelrob · 6th Dec 2021, 8:48 pm

Hi all,
I am after a bit of advice if possible I would like to obtain a piece of kit to do fm and am alignment, I am working on a marconi t69da and the instructions say it needs a 10.7 mhz signal which seems pretty common.
This is not something I'm going to be doing daily so don't want to pay a fortune but would like to be able to do it myself plus I don't want to buy something of no use to me.
I have attached the alignment info for this set its my first time so any advice would be great.
As yet I don't have an oscilloscope but had an analogue meter.

Thanks in advance.
Rob.

HamishBoxer · 6th Dec 2021, 9:09 pm

You need by the sound of things an AM/FM signal generator, IF of course it really does need aligning.

reeltoreelrob · 6th Dec 2021, 11:21 pm

It's a set I have had for years not working but put my mind to it I have swapped the hunts and found a resistor o/c. It is now working but the stations are out of sync with the scale and the tuning cap is at full extreme when tuned to radio 2 that should be 88.3 by me, also there is some hum when tuned into an fm station that disappears just as its tuned out of the station.

Simon Gittins · 7th Dec 2021, 10:47 am

Getting the stations back in sync with the scale could be done by slight adjustment of L6 when tuned into Radio 2, however, as this set only goes up to 100MHz it is possible that someone has already adjusted it to enable Classic FM to be tuned in at the top of the scale.

The hum when tuned into a station may be modulation hum. You say you have already replaced the Hunts capacitors but the 0.2uF capacitor from the rectifier anode to chassis (C60 on R&TV sheet) might cause this (replacement needs to be Class X type).

reeltoreelrob · 7th Dec 2021, 5:23 pm

Hi
Thanks for the tip on the x cap, I did see it on the schematic so replaced it as a matter of course before trying the set again. Even though there was no mains hum from the amp the smoothing can was getting hot and overloading a resistor and making it run red.

I wondered if someone else had moved the L6 coil to make way for stations over 100mhz but thinking about it I must have bought the set from a jumble sale in the late 80s and I think that's before classic and even heart fm started but yes someone could have fiddled with it.
It says set to 91 and tune L6 in I have a basic transmitter that I can do that with.

Any idea on the reliability of the red caps in these sets, I've not tested any as yet.

Thanks for the ideas,
Much appreciated.

simpsons · 7th Dec 2021, 6:01 pm

Rob

When first starting out repairing radios, the instructions for alignment are seen as sacrosanct but, except for the IF instructions, there is a little wriggle room.

This is not a communications receiver with a digital display and so setting the dial to 91Mhz + or - 50 kHz by eye and hoping your FM transmitter is within acceptable limits is not necessary.

The BBC transmitter at 88.3 fits in with your dial marker at 88Mhz and without a mirror scale you won't get better.

The same applies to the other end of the scale where Classic FM at 100.1 Mhz is as good as 100 any day.

Hope this helps

Chris

reeltoreelrob · 7th Dec 2021, 6:33 pm

Hi Chris
Yes fully agree, this is far from a precision set so if the marker is in and around 88.3 for radio 2 that's good enough, and If I can keep heart fm at the other end that's a bonus, the L6 coil adjuster looks fun to get at through the hole in the side but that will be something for the weekend.

All the best
Rob.

simpsons · 7th Dec 2021, 7:29 pm

Hi again Rob

Just something before you align the FM dial, rock the tuning from one end of the dial to the other to make sure the pointer is within the limits of the dial both sides.

Also, just be very careful when adjusting the FM oscillator coil as after years of service the ferrite slug may be reluctant to move.

I use a plastic knitting needle shaped as a thin flat bladed screwdriver.

Look at the coil, using a mirror if necessary and, the type of slot in the ferrite slug. If the same as the IF then you have a template.

Turn the slug first just a little anti clockwise and then clockwise to free it. Don't use too much pressure otherwise the slug might just push through the coil former, then you are in trouble.

Tune in Radio 2 and very slightly move the pointer towards the correct marker and adjust the coil, repeat until your happy.

I can't see a trimmer capacitor in the schematic for the other end of the scale (100mHz) but this might be because I'm looking at the HMV version or just that when this radio was sold, there was nothing to listen to there and so why correct any slight misalignment!!

Chris

reeltoreelrob · 7th Dec 2021, 8:15 pm

Hi, Chris
I have looked at the adjustment and it looks like a hex not a flat head so that might make it a little bit more awkward but yes a very valid point it won't have been moved for years so I will be really careful.
I'll do an update on how I get on.
When I bought it there was just no reception just amp sound, and I have yet to have it running in its case with the metal strip that's used as an aerial in the correct position in the case, I have say it seems to have good volume for what it is.
Thanks again for your help.
All the best
Rob.

simpsons · 8th Dec 2021, 12:23 am

Hi Rob

I wouldn't adjust a hex headed ferrite core without a proper, by that I mean, manufactured plastic tool.

I say that because the ferrite core is almost hollow and any stress will fracture the slug and make it impossible to move. It will then require drilling out.

I no longer have one to give you but maybe a BVWS Member can help.

I will have a look on eBay tomorrow. The alignment tool is called: Double Hex End Alignment Tool.

From memory, a similar adjustment tool can be found on /Sony/Grundig Colour TV Convergence Panels. I'll have a look in my box of "one day I might need this!!"

Chris

Herald1360 · 8th Dec 2021, 12:41 am

Quote:

Originally Posted by simpsons

....

I can't see a trimmer capacitor in the schematic for the other end of the scale (100mHz) but this might be because I'm looking at the HMV version or just that when this radio was sold, there was nothing to listen to there and so why correct any slight misalignment!!

Chris

Might this be why the alignment point for L6 is 91MHz (probably Mc/s in the data)? That would be slap in the middle of the original Light, Third, Home FM station range.

reeltoreelrob · 8th Dec 2021, 11:56 am

Hi both,
Yes it does say 10.7 Mc/s in the service data.
To be honest I hadn't thought about the possibility I'd it breaking I'll take a photo of it later and post it on here.
All the best Rob.

simpsons · 8th Dec 2021, 5:26 pm

Rob

It is so easy to get bamboozled by technical terms when first starting out on repairing radios and perhaps that is why, in your last post, you mention 10.7Mhz.

10.7 Mhz is the intermediate or IF frequency for FM or VHF reception.

470 Khz is the intermediate or IF frequency for AM or MW/LW reception.

To correct the dial alignment, you do not need to adjust either of these IF transformers.

I would go further unless someone has adjusted the IF transformers, these are the ones you can see on the printed circuit board inside aluminium cans, leave them alone as it is unusual for them to require adjustment and when doing so, you will need a little more help.

AND

You will need for your radio a calibrated Signal Generator that would cost around £80 for an old good'un and a multimeter. For stereo receivers, an AM/FM signal generator and an oscilloscope would be on your shopping list. The sky is the limit there.

Chris

reeltoreelrob · 8th Dec 2021, 6:07 pm

Hi Chris
Sorry I think I may have worded thing wrong, I was answering Heralds question when he said it would be worded as Mc/s rather than khz.
I know I need to adjust the RF to get the scale back on track and to be fair I have reconnected the aerial wire that bolts on top of the inside of the set and reception doesn't seem bad so the I.F cans can probably be left as you say I have taken a pic of the hex slug I'll pop it on the following post.

I would still like to pick up a signal generator any advice on a suitable make/ model would be great I have been collecting radios, record players, tape recorders for years.

Thank you so much for your help and guidance it is very much appreciated.
All the best Rob

reeltoreelrob · 8th Dec 2021, 6:10 pm

Not the best pic in the world, the hex can just be seen.

majoconz · 8th Dec 2021, 7:23 pm

Quote:

the smoothing can was getting hot and overloading a resistor and making it run red.

This plus the hum are the classic symptoms that the smoothing capacitor will explode soon..... !

simpsons · 8th Dec 2021, 7:51 pm

Hi Rob

Thank you for the picture.

I have taken the Grundig "hex" adjuster tool apart and whilst many would say it was over engineered, in fact it is fool proof using a plastic threaded hex screw bonded to the ferrite slug. Whilst this means that there is no chance of damaging the ferrite slug, it also means that the adjuster is the wrong size.

The same goes for the Sony.

In the past, I have used a metric hex Allen Key noting that it will alter the tuning when inserted but with a little patience will do the job. Once you know which way to turn then it isn't difficult to get it right.

Should you have a set of hex keys, just make sure that you insert the key far enough in to ensure that there is no stress to the ferrite slug.

As for a RF signal generator, how about first of all placing a request in the BVWS "Sets, parts and service information wanted section."

There are a few members following your efforts so no pressure here then!

Keep in touch and good luck

Chris

reeltoreelrob · 8th Dec 2021, 8:26 pm

A big thank you!!!
I'll keep everyone posted how I get on whether it be good or not so good.

reeltoreelrob · 9th Dec 2021, 7:56 pm

Hi all,
Just a little update on this set, I managed to find the correct hex key to move the slug but as Chris implied might happen the slug just crumbled even with very gentle back and forth pressure, so its decision time whether to try and remove and obtain a replacement slug or break the set up and top up the spares bin
All the best
Rob.

6th Dec 2021, 8:48 pm	#1
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Alignment device Hi all, I am after a bit of advice if possible I would like to obtain a piece of kit to do fm and am alignment, I am working on a marconi t69da and the instructions say it needs a 10.7 mhz signal which seems pretty common. This is not something I'm going to be doing daily so don't want to pay a fortune but would like to be able to do it myself plus I don't want to buy something of no use to me. I have attached the alignment info for this set its my first time so any advice would be great. As yet I don't have an oscilloscope but had an analogue meter. Thanks in advance. Rob. Attached Thumbnails

6th Dec 2021, 9:09 pm	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Alignment device You need by the sound of things an AM/FM signal generator, IF of course it really does need aligning. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

6th Dec 2021, 11:21 pm	#3
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device It's a set I have had for years not working but put my mind to it I have swapped the hunts and found a resistor o/c. It is now working but the stations are out of sync with the scale and the tuning cap is at full extreme when tuned to radio 2 that should be 88.3 by me, also there is some hum when tuned into an fm station that disappears just as its tuned out of the station.

7th Dec 2021, 10:47 am	#4
Simon Gittins Heptode Join Date: Jan 2006 Location: Cornwall, UK. Posts: 506	Re: Alignment device Getting the stations back in sync with the scale could be done by slight adjustment of L6 when tuned into Radio 2, however, as this set only goes up to 100MHz it is possible that someone has already adjusted it to enable Classic FM to be tuned in at the top of the scale. The hum when tuned into a station may be modulation hum. You say you have already replaced the Hunts capacitors but the 0.2uF capacitor from the rectifier anode to chassis (C60 on R&TV sheet) might cause this (replacement needs to be Class X type).

7th Dec 2021, 5:23 pm	#5
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Hi Thanks for the tip on the x cap, I did see it on the schematic so replaced it as a matter of course before trying the set again. Even though there was no mains hum from the amp the smoothing can was getting hot and overloading a resistor and making it run red. I wondered if someone else had moved the L6 coil to make way for stations over 100mhz but thinking about it I must have bought the set from a jumble sale in the late 80s and I think that's before classic and even heart fm started but yes someone could have fiddled with it. It says set to 91 and tune L6 in I have a basic transmitter that I can do that with. Any idea on the reliability of the red caps in these sets, I've not tested any as yet. Thanks for the ideas, Much appreciated.

7th Dec 2021, 6:01 pm	#6
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Alignment device Rob When first starting out repairing radios, the instructions for alignment are seen as sacrosanct but, except for the IF instructions, there is a little wriggle room. This is not a communications receiver with a digital display and so setting the dial to 91Mhz + or - 50 kHz by eye and hoping your FM transmitter is within acceptable limits is not necessary. The BBC transmitter at 88.3 fits in with your dial marker at 88Mhz and without a mirror scale you won't get better. The same applies to the other end of the scale where Classic FM at 100.1 Mhz is as good as 100 any day. Hope this helps Chris

7th Dec 2021, 6:33 pm	#7
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Hi Chris Yes fully agree, this is far from a precision set so if the marker is in and around 88.3 for radio 2 that's good enough, and If I can keep heart fm at the other end that's a bonus, the L6 coil adjuster looks fun to get at through the hole in the side but that will be something for the weekend. All the best Rob.

7th Dec 2021, 7:29 pm	#8
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Alignment device Hi again Rob Just something before you align the FM dial, rock the tuning from one end of the dial to the other to make sure the pointer is within the limits of the dial both sides. Also, just be very careful when adjusting the FM oscillator coil as after years of service the ferrite slug may be reluctant to move. I use a plastic knitting needle shaped as a thin flat bladed screwdriver. Look at the coil, using a mirror if necessary and, the type of slot in the ferrite slug. If the same as the IF then you have a template. Turn the slug first just a little anti clockwise and then clockwise to free it. Don't use too much pressure otherwise the slug might just push through the coil former, then you are in trouble. Tune in Radio 2 and very slightly move the pointer towards the correct marker and adjust the coil, repeat until your happy. I can't see a trimmer capacitor in the schematic for the other end of the scale (100mHz) but this might be because I'm looking at the HMV version or just that when this radio was sold, there was nothing to listen to there and so why correct any slight misalignment!! Chris

7th Dec 2021, 8:15 pm	#9
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Hi, Chris I have looked at the adjustment and it looks like a hex not a flat head so that might make it a little bit more awkward but yes a very valid point it won't have been moved for years so I will be really careful. I'll do an update on how I get on. When I bought it there was just no reception just amp sound, and I have yet to have it running in its case with the metal strip that's used as an aerial in the correct position in the case, I have say it seems to have good volume for what it is. Thanks again for your help. All the best Rob.

8th Dec 2021, 12:23 am	#10
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Alignment device Hi Rob I wouldn't adjust a hex headed ferrite core without a proper, by that I mean, manufactured plastic tool. I say that because the ferrite core is almost hollow and any stress will fracture the slug and make it impossible to move. It will then require drilling out. I no longer have one to give you but maybe a BVWS Member can help. I will have a look on eBay tomorrow. The alignment tool is called: Double Hex End Alignment Tool. From memory, a similar adjustment tool can be found on /Sony/Grundig Colour TV Convergence Panels. I'll have a look in my box of "one day I might need this!!" Chris

8th Dec 2021, 11:56 am	#12
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Hi both, Yes it does say 10.7 Mc/s in the service data. To be honest I hadn't thought about the possibility I'd it breaking I'll take a photo of it later and post it on here. All the best Rob.

8th Dec 2021, 5:26 pm	#13
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Alignment device Rob It is so easy to get bamboozled by technical terms when first starting out on repairing radios and perhaps that is why, in your last post, you mention 10.7Mhz. 10.7 Mhz is the intermediate or IF frequency for FM or VHF reception. 470 Khz is the intermediate or IF frequency for AM or MW/LW reception. To correct the dial alignment, you do not need to adjust either of these IF transformers. I would go further unless someone has adjusted the IF transformers, these are the ones you can see on the printed circuit board inside aluminium cans, leave them alone as it is unusual for them to require adjustment and when doing so, you will need a little more help. AND You will need for your radio a calibrated Signal Generator that would cost around £80 for an old good'un and a multimeter. For stereo receivers, an AM/FM signal generator and an oscilloscope would be on your shopping list. The sky is the limit there. Chris

8th Dec 2021, 6:07 pm	#14
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Hi Chris Sorry I think I may have worded thing wrong, I was answering Heralds question when he said it would be worded as Mc/s rather than khz. I know I need to adjust the RF to get the scale back on track and to be fair I have reconnected the aerial wire that bolts on top of the inside of the set and reception doesn't seem bad so the I.F cans can probably be left as you say I have taken a pic of the hex slug I'll pop it on the following post. I would still like to pick up a signal generator any advice on a suitable make/ model would be great I have been collecting radios, record players, tape recorders for years. Thank you so much for your help and guidance it is very much appreciated. All the best Rob

8th Dec 2021, 6:10 pm	#15
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Not the best pic in the world, the hex can just be seen. Attached Thumbnails

8th Dec 2021, 7:51 pm	#17
simpsons Octode Join Date: Feb 2007 Location: Harrow, London, UK. Posts: 1,493	Re: Alignment device Hi Rob Thank you for the picture. I have taken the Grundig "hex" adjuster tool apart and whilst many would say it was over engineered, in fact it is fool proof using a plastic threaded hex screw bonded to the ferrite slug. Whilst this means that there is no chance of damaging the ferrite slug, it also means that the adjuster is the wrong size. The same goes for the Sony. In the past, I have used a metric hex Allen Key noting that it will alter the tuning when inserted but with a little patience will do the job. Once you know which way to turn then it isn't difficult to get it right. Should you have a set of hex keys, just make sure that you insert the key far enough in to ensure that there is no stress to the ferrite slug. As for a RF signal generator, how about first of all placing a request in the BVWS "Sets, parts and service information wanted section." There are a few members following your efforts so no pressure here then! Keep in touch and good luck Chris

8th Dec 2021, 8:26 pm	#18
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device A big thank you!!! I'll keep everyone posted how I get on whether it be good or not so good.

9th Dec 2021, 7:56 pm	#19
reeltoreelrob Pentode Join Date: Nov 2010 Location: Birmingham, West Midlands, UK. Posts: 202	Re: Alignment device Hi all, Just a little update on this set, I managed to find the correct hex key to move the slug but as Chris implied might happen the slug just crumbled even with very gentle back and forth pressure, so its decision time whether to try and remove and obtain a replacement slug or break the set up and top up the spares bin All the best Rob.