UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Closed Thread
 
Thread Tools
Old 4th May 2020, 10:57 am   #121
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by poppydog View Post
Quote:
Originally Posted by Andrew2 View Post
I've been stepping quietly past this thread for several days now, imagining it would be one of those 'after a quick dry-out and some new batteries...' types.
But I've just read through it and it's a real epic! When I saw those first three pictures I was going to tell you to scrap it and not drive yourself bonkers by even thinking of fixing it!
Your patience and tenacity deserve a medal!
As long as no other radios that could be put back into use are butchered to get this thing going again. The "transistor" radio seems to get in the neck on here more than the valve sets in that elusive search to make the perfect set.

poppydog
I prefer radios that are not perfect, no one will argue I am not restoring it the wright way! lol and I like stuff to show some history, after this I do have some other projects, most valve, one is I think a bush tv22 siting in my hall in a cardboard box, sadly without Bakelite case, and completely original and untouched. I'm afraid to touch that one! Is it rare? many years ago I went to the Bakelite museum and they had a TV that looked the same and said that's many back in the day where turned into fish bowls? I think the museum put modern colour CRT TV workings in the bush case

Last edited by audion_1908; 4th May 2020 at 11:04 am.
audion_1908 is offline  
Old 4th May 2020, 12:29 pm   #122
Philips210
Nonode
 
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by audion_1908 View Post
Test setup
Attachment 204824

Attachment 204825

Tests side with 2 pins 4.7ohm 0.11mH with ferrite on, 4.7ohm 0.08mH without.
Tests side with 3 pins outer set 7.5ohm 0.35mH, 0.43mH with ferrite.
5.3ohm 0.10mH center to one side 4.2ohm 0.11mH to the other, both with ferrite

It looks like there is a tubular ceramic capacitor in the base, but doesn't seem to show up on the test?
The tubular ceramic capacitor appears to be wired across the outer of the three pins on the other side.
This seems to show the wires are good, but I don't know how to read the uncalibrated test gear results.
I think I'll consider all the other IF can good until proven otherwise as it's likely to destroy the PCB taking them all off! As the copper track has a tendency of coming off the PCB

I am waiting for some solder wick to turn up

And the ferrite core turns freely! It is a surprise that the cores seems to be ok

Hi.

When I get a chance I'll try to take some inductance measurements on my AM radio IFTs. They are mostly interchangeable from other make sets changing like for like obviously. I did however read that there can be a variation in the phasing of the windings ie the start/finish of one winding in relation to another. Installing the wrong type will certainly not work from what I gather. I think it was ex forum member Argus25 that pointed this out a little while back.

Re your IFTs. If I was to refit the IFT that you've tested then I'd want to confirm that the ceramic cap is in order first. It looks a bit fiddly to see with the wax.

A good test would be check that the IFT will resonate at the radio's correct IF. I can't recall where I saw this demonstrated but there was a simple test bed circuit in one of the magazines. You'd use an RF signal generator and oscilloscope. If you have a wobbulator (sweep generator) it would be a good way to check the response curve of the IFT.

Regards,
Symon
Philips210 is offline  
Old 4th May 2020, 12:54 pm   #123
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by Philips210 View Post
Quote:
Originally Posted by audion_1908 View Post
Test setup
Attachment 204824

Attachment 204825

Tests side with 2 pins 4.7ohm 0.11mH with ferrite on, 4.7ohm 0.08mH without.
Tests side with 3 pins outer set 7.5ohm 0.35mH, 0.43mH with ferrite.
5.3ohm 0.10mH center to one side 4.2ohm 0.11mH to the other, both with ferrite

It looks like there is a tubular ceramic capacitor in the base, but doesn't seem to show up on the test?
The tubular ceramic capacitor appears to be wired across the outer of the three pins on the other side.
This seems to show the wires are good, but I don't know how to read the uncalibrated test gear results.
I think I'll consider all the other IF can good until proven otherwise as it's likely to destroy the PCB taking them all off! As the copper track has a tendency of coming off the PCB

I am waiting for some solder wick to turn up

And the ferrite core turns freely! It is a surprise that the cores seems to be ok

Hi.

When I get a chance I'll try to take some inductance measurements on my AM radio IFTs. They are mostly interchangeable from other make sets changing like for like obviously. I did however read that there can be a variation in the phasing of the windings ie the start/finish of one winding in relation to another. Installing the wrong type will certainly not work from what I gather. I think it was ex forum member Argus25 that pointed this out a little while back.

Re your IFTs. If I was to refit the IFT that you've tested then I'd want to confirm that the ceramic cap is in order first. It looks a bit fiddly to see with the wax.

A good test would be check that the IFT will resonate at the radio's correct IF. I can't recall where I saw this demonstrated but there was a simple test bed circuit in one of the magazines. You'd use an RF signal generator and oscilloscope. If you have a wobbulator (sweep generator) it would be a good way to check the response curve of the IFT.

Regards,
Symon
I have no signal generator but do have a CRT oscilloscope but it need recapping, it's a Griffin brand, I think ment for schools, can't find a schematic, I'll be interested
in the test circuit.

Like this ?
Click image for larger version

Name:	3554993200_1353229104.gif
Views:	60
Size:	9.5 KB
ID:	204859
From http://theradioboard.com/rb/viewtopic.php?t=7750
Identifying and testing unknown IF transformers?

Is 390ohms right on the base? I probably have all the parts

Last edited by audion_1908; 4th May 2020 at 1:11 pm.
audion_1908 is offline  
Old 4th May 2020, 1:15 pm   #124
ekjdm14
Banned
 
Join Date: Feb 2019
Location: Congleton, Cheshire, UK.
Posts: 609
Default Re: Wet 1969 ITT-KB junior battery radio

When you say the 'scope needs recapping, does it function at all? I tend to not worry so much about the accuracy of my old Philips 'scope but just the ability to display a trace & show if something's oscillating or not. For the purposes of this test I'd expect an uncalibrated/inaccurate 'scope to be just as useful.

(Same story with my sig gen, suspect a weak valve so it works around 150-900Kc/s but anything outside those ranges it dies! It's supposed to go up to something like 180Mc/s!)

It's good that the IFT's appear to have been filled with goop as it should have preserved them, I'd agree with leaving the rest in place on an "innocent until proven guilty" basis. If that cap across the base has died, I'd bet Shango's Silver-Mica disease repair method of leaving the core roughly where it started & adding a trimmer cap and tuning that to find the value would work. (or just throw 100pF across it if you're feeling the Jason JJ Cruz vibe).
ekjdm14 is offline  
Old 4th May 2020, 1:53 pm   #125
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by ekjdm14 View Post
When you say the 'scope needs recapping, does it function at all? I tend to not worry so much about the accuracy of my old Philips 'scope but just the ability to display a trace & show if something's oscillating or not. For the purposes of this test I'd expect an uncalibrated/inaccurate 'scope to be just as useful.

(Same story with my sig gen, suspect a weak valve so it works around 150-900Kc/s but anything outside those ranges it dies! It's supposed to go up to something like 180Mc/s!)

It's good that the IFT's appear to have been filled with goop as it should have preserved them, I'd agree with leaving the rest in place on an "innocent until proven guilty" basis. If that cap across the base has died, I'd bet Shango's Silver-Mica disease repair method of leaving the core roughly where it started & adding a trimmer cap and tuning that to find the value would work. (or just throw 100pF across it if you're feeling the Jason JJ Cruz vibe).
The oscilloscope is full of original paper capacitors and original electrolytic smoothing cans neither I trust, if the capacitors are bad they will burn out the valves, and power transformer.

If I have the IF transformers open I can cut the wires to the capacitor in the base of needed and use an external cap like you sed, but I want to test it first, also I have no Silver-Mica caps.

I will attempt to build the ift test circuit with what I have, where is best to connect the oscilloscope?

Last edited by audion_1908; 4th May 2020 at 2:10 pm.
audion_1908 is offline  
Old 4th May 2020, 2:09 pm   #126
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Click image for larger version

Name:	IMG_20200504_140540.jpg
Views:	79
Size:	50.7 KB
ID:	204870
I found the kit box for the universal component tester, it looks much better now, and I am less likely to brake it.
audion_1908 is offline  
Old 4th May 2020, 7:22 pm   #127
Philips210
Nonode
 
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
Default Re: Wet 1969 ITT-KB junior battery radio

Hi.

Re. the pic in post #123 that's a BFO type circuit and was not what I'd seen before for testing IFTs and I am not sure how this can be used. I believe it can be used in conjunction with another AM radio using the same IF and peaking the test IFT for heterodyning. Maybe another forum member can explain how that circuit can be used in practice for the TOKO IFTs and regarding coupling etc.

I think one way to test the IFT is to apply the correct IF (say 455kHz) from a signal generator and look at the sinewave on the 'scope and peak the ferrite screw for maximum amplitude. Again, if any other forum member with more experience, particularly with the TOKO IFTs, can share their method of testing it would be great to see their aproach.

All my testing of IFTs has mainly been setting them up in circuit by peaking their response at the required IF by using the standard setup of RF signal generator and output meter across the loudspeaker. I sometimes bring out the wobbulator and 'scope but it's a more involved process.

Regards,
Symon
Philips210 is offline  
Old 4th May 2020, 7:32 pm   #128
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Wet 1969 ITT-KB junior battery radio

I can't see what the problem is. Just give it a wipe with a damp cloth and realign it. Done!
I found an HMV 1807 television chassis buried in a garden at Crawley. Some of the components had literally dissolved and all the pins on the tube were rusting away. J.
Heatercathodeshort is offline  
Old 4th May 2020, 7:52 pm   #129
Philips210
Nonode
 
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
Default Re: Wet 1969 ITT-KB junior battery radio

Hi

Talking about corrosion and valve pins in particular, you sometimes come across valves with really bad green corrosion on the pins and wondered there must be something more than just damp that's caused it. I think I read that in some Kradlepak boxes that Mullard used this could be a problem.

I tried an experiment, back in 2010 by putting a faulty 6F22 valve from my GEC BT322 out in the garden where if was well exposed to the elements but not in a place where it would get broken. The idea being to find out how the pins will cope. I retrieved it a few months ago after 10 years out in the open. I was amazed to find the pins corrosion free. How can that be so?

Regards,
Symon
Philips210 is offline  
Old 4th May 2020, 7:58 pm   #130
Philips210
Nonode
 
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by Heatercathodeshort View Post
Just give it a wipe with a damp cloth and realign it. Done!
HA Ha I think the last thing audion_1908's radio needs is any more damp.

Regards,
Symon
Philips210 is offline  
Old 4th May 2020, 8:00 pm   #131
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by Heatercathodeshort View Post
I can't see what the problem is. Just give it a wipe with a damp cloth and realign it. Done!
I found an HMV 1807 television chassis buried in a garden at Crawley. Some of the components had literally dissolved and all the pins on the tube were rusting away. J.
Do you have a thread on that? I would like to see, did you get it going? I'm not the only person that likes lost causes
audion_1908 is offline  
Old 4th May 2020, 8:02 pm   #132
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by Philips210 View Post
Quote:
Originally Posted by Heatercathodeshort View Post
Just give it a wipe with a damp cloth and realign it. Done!
HA Ha I think the last thing audion_1908's radio needs is any more damp.

Regards,
Symon
It's been scrubbed in a sink! As I thought water can't do any more damage!
audion_1908 is offline  
Old 4th May 2020, 9:00 pm   #133
Lloyd 1985
Nonode
 
Lloyd 1985's Avatar
 
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
Default Re: Wet 1969 ITT-KB junior battery radio

I've been restoring an Ekco A22 since last may, and that was a rusted heap! It's still not as bad as your radio though! A22 restoration thread

I've had a go at some pretty rusted up speakers before, even made them work well again! But I think I'll pass on your one, I think it would be best to lay it to rest somewhere nice!

Regards,
Lloyd.
Lloyd 1985 is offline  
Old 4th May 2020, 9:19 pm   #134
ekjdm14
Banned
 
Join Date: Feb 2019
Location: Congleton, Cheshire, UK.
Posts: 609
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by audion_1908 View Post
Quote:
Originally Posted by Philips210 View Post
Quote:
Originally Posted by Heatercathodeshort View Post
Just give it a wipe with a damp cloth and realign it. Done!
HA Ha I think the last thing audion_1908's radio needs is any more damp.

Regards,
Symon
It's been scrubbed in a sink! As I thought water can't do any more damage!
Scrubbed in a sink? I thought it DID sink?

Agree I'd like to see the thread on that garden telly if there is one!

On the 'scope, I hadn't realised it was that age to have paper caps. Of course wouldn't suggest powering up anything I cared about with those in place! My PM3200X is just new enough to be fully transistorised (which was fun repairing as could only find the schematic for the ECC83 version, and even then only in Dutch! Got there in the end though!)

Oh and Lloyd I think perhaps someone had attempted to lay that 'speaker to rest some decades ago, along with the radio it was contained in, only for it to be exhumed by an Ebayer. God alone knows what'd happen if the remnants of the unusable parts from this resurrection are dug up yet again sometime around 2065...
ekjdm14 is offline  
Old 5th May 2020, 12:18 am   #135
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by ekjdm14 View Post
Quote:
Originally Posted by audion_1908 View Post
Quote:
Originally Posted by Philips210 View Post

HA Ha I think the last thing audion_1908's radio needs is any more damp.

Regards,
Symon
It's been scrubbed in a sink! As I thought water can't do any more damage!
Scrubbed in a sink? I thought it DID sink?

Agree I'd like to see the thread on that garden telly if there is one!

On the 'scope, I hadn't realised it was that age to have paper caps. Of course wouldn't suggest powering up anything I cared about with those in place! My PM3200X is just new enough to be fully transistorised (which was fun repairing as could only find the schematic for the ECC83 version, and even then only in Dutch! Got there in the end though!)

Oh and Lloyd I think perhaps someone had attempted to lay that 'speaker to rest some decades ago, along with the radio it was contained in, only for it to be exhumed by an Ebayer. God alone knows what'd happen if the remnants of the unusable parts from this resurrection are dug up yet again sometime around 2065...
I got the Griffin oscilloscope out to have another look at it, it has a lose wire, one power resistor burnt up, another apparently dissolved in flux! most of the valve labels worn off, handful or electrolytic likely need replacing, a stack of capacitors that might be paper or early plastic film, labelled sparg 4 electrolytic capacitors cans that need replacing or reforming, and a mains transformer, taped at 120v? but labled 240v on the back, the mullard mustards caps from my brief research data it to the 60s or 70s, if I had a schematic it would not be a big problem, its used single sided PCBs all hand soldered and unshielded wires everywhere! Single beam and maybe 1mhz, and uses banana plugs for signal! The scope needs its own thread! At least there's no trace of rust in it!
One thing I will do to the radio and scope when done is glue in a schematic, and maybe folding in a full service manual, to help the next person in there.

Dose any one think I should start a thread on the Griffin scope?

2065 that's only 45 years 2089 is more like it 51 years, I hope it doesn't get buried again

Last edited by audion_1908; 5th May 2020 at 12:25 am.
audion_1908 is offline  
Old 5th May 2020, 12:39 am   #136
ekjdm14
Banned
 
Join Date: Feb 2019
Location: Congleton, Cheshire, UK.
Posts: 609
Default Re: Wet 1969 ITT-KB junior battery radio

It'd be interesting to see a thread on the 'scope yes, if it has Sprague caps could it be American or perhaps taken to the US at some point in it's life? (Just pondering on the 120v/240v conundrum, if it is set up for 120v and someone tried a power-up over here it might account for the burned resistors :/ )

Is it a valve or transistor model (or hybrid)?
ekjdm14 is offline  
Old 5th May 2020, 12:57 am   #137
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

The scope is not American, apparently it was made by a company called scopex but rebranded Griffin, for use in uk schools and colleges, and uses a weird transformer hookup, it has no blown fuses, a 3amp in the plug and 1amp glass in the scope

my new cheap soldering iron tip is total rubbish, I will try filing it down tomorrow, as it's useless

Last edited by audion_1908; 5th May 2020 at 1:17 am.
audion_1908 is offline  
Old 5th May 2020, 1:11 am   #138
audion_1908
Hexode
 
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by Philips210 View Post
Hi.

Re. the pic in post #123 that's a BFO type circuit and was not what I'd seen before for testing IFTs and I am not sure how this can be used. I believe it can be used in conjunction with another AM radio using the same IF and peaking the test IFT for heterodyning. Maybe another forum member can explain how that circuit can be used in practice for the TOKO IFTs and regarding coupling etc.

I think one way to test the IFT is to apply the correct IF (say 455kHz) from a signal generator and look at the sinewave on the 'scope and peak the ferrite screw for maximum amplitude. Again, if any other forum member with more experience, particularly with the TOKO IFTs, can share their method of testing it would be great to see their aproach.

All my testing of IFTs has mainly been setting them up in circuit by peaking their response at the required IF by using the standard setup of RF signal generator and output meter across the loudspeaker. I sometimes bring out the wobbulator and 'scope but it's a more involved process.

Regards,
Symon
I just read this after building the circuit!

Before, the scrap pcb
Click image for larger version

Name:	IMG_20200504_140526.jpg
Views:	78
Size:	40.5 KB
ID:	204909

Bfo circuit, used nealy all recycle components only the 2n2222 transistor and the solder where new, I even pulled off the terminals off a dead 9-volt battery to make the 9 volt socket, it did prove to me it's not the 51 year old radios solder that's the problem but my soldering iron tip, I have a new one in the post and will try filing the old one down tomorrow
Click image for larger version

Name:	IMG_20200505_010111.jpg
Views:	76
Size:	34.3 KB
ID:	204910
I even reused 2 of the PCBs original components without moving them, I have found I should not have trusted 10+ year old 2 part epoxy I got in a £1 shop, it seems to have stalled while curing, and has the consistency of toffee hopefully sitting on a shelf overnight will improve it, any tips to try and harden it?
audion_1908 is offline  
Old 5th May 2020, 1:23 am   #139
Refugee
Dekatron
 
Refugee's Avatar
 
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
Default Re: Wet 1969 ITT-KB junior battery radio

That looks like a single transistor oscillator.
You just connect up the IFT and set the gain with a small preset pot in the emitter of the transistor until you get a clean sine wave on a scope.
A frequency counter should read the IF frequency.
Refugee is offline  
Old 5th May 2020, 12:46 pm   #140
Philips210
Nonode
 
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
Default Re: Wet 1969 ITT-KB junior battery radio

Quote:
Originally Posted by audion_1908 View Post
Test setup
Attachment 204824

Attachment 204825

Tests side with 2 pins 4.7ohm 0.11mH with ferrite on, 4.7ohm 0.08mH without.
Tests side with 3 pins outer set 7.5ohm 0.35mH, 0.43mH with ferrite.
5.3ohm 0.10mH center to one side 4.2ohm 0.11mH to the other, both with ferrite

It looks like there is a tubular ceramic capacitor in the base, but doesn't seem to show up on the test?
The tubular ceramic capacitor appears to be wired across the outer of the three pins on the other side.
This seems to show the wires are good, but I don't know how to read the uncalibrated test gear results.
I think I'll consider all the other IF can good until proven otherwise as it's likely to destroy the PCB taking them all off! As the copper track has a tendency of coming off the PCB

I am waiting for some solder wick to turn up

And the ferrite core turns freely! It is a surprise that the cores seems to be ok

Hi.

I have done a few L and R checks for a TOKO 10T1 4603 IF transformer removed from my ITT Junior 21 see attached pic for details. Incidentally, does your screening can still have any legible markings left on it?

I'll try to do some checks with the RF signal generator and 'scope later when I have the time. I'll also try out that BFO circuit and see if it will work in practice. These tests are going to be more meaningful than static L and R checks.

Regards,
Symon
Attached Thumbnails
Click image for larger version

Name:	TOKO 4603001.jpg
Views:	54
Size:	61.1 KB
ID:	204931  
Philips210 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 8:56 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.