Wireless World noise reducer - UK Vintage Radio Repair and Restoration Discussion Forum

cxaaron · 19th Jan 2016, 9:19 pm

This unit was avaliable in kit form in the mid seventies but it does not power up. The power switch and the cables from the plug and fuses all test good for continuity. I'm kind of a beginner but have a little knowledge and would like to know what to test next.

There are no valves in this unit.

Thanks .

Station X · 19th Jan 2016, 9:52 pm

Can you post a circuit please.

Ed_Dinning · 19th Jan 2016, 10:13 pm

From memory this was based on Dolby circuits and was sold by one or two of the WW advertisers.

ed

KeithsTV · 19th Jan 2016, 10:24 pm

I built one of these units when it came out and have the articles and the information that came with the kit. I'll see if I can find it and scan it. I've also still got the unit up in the loft.

Keith

ajs37 · 19th Jan 2016, 10:27 pm

yes - Integrex sold them - I built one which I probably still have in my garage - worked very well - can't remember much about it though (it was over 30 years ago!) - circuit diagram would certainly help.
Andy

KeithsTV · 19th Jan 2016, 10:47 pm

That was easier than I thought. it was in the first place I looked - most unusual!

I bought the Integrex kit and these are the instructions that came with the kit.

If it's not powering up and the leads switch and internal fuse are OK it could be the mains transformer. Try measuring the resistance across the mains lead with the power switch on. You should see the resistance of the mains transformer primary probably a few hundred ohms.

Keith

Radio Wrangler · 20th Jan 2016, 12:15 am

The bit to be careful about is that the kit will include a pair of specially selected FETs which are probably irreplaceable now as I doubt anyone now knows what characteristic they were selected for.

The circuits, as I remember were by Dolby labs who were happy with private construction and supplier the FETs.

David

Michael Maurice · 20th Jan 2016, 12:35 am

Looking at that diagram, if its completely dead, then it can only be the mains cable, fuse, switch, transformer.

Unless the bulb is open circuit it should light up

cxaaron · 20th Jan 2016, 12:49 am

Hi, used to swapping out bad components but never had to diagnose a problem with power up before. So i measured resistance on the continuity setting, on the red side of the transformer across ways brown to blue wire with a reading of 011, and on the opposite side, yellow it read 1004. Test was done with the unit unplugged from the wall with power switch on, was this correct? thanks.

cxaaron · 20th Jan 2016, 1:10 am

Thanks Keith for scanning the file, you're very kind.

KeithsTV · 20th Jan 2016, 8:28 am

That looks as if the transformer is OK. The yellow side is the primary. Can you measure the resistance across the mains lead (brown and blue) at the 13A plug with the power switch in the on position. This will check the mains lead, power switch and fuse. You should get a similar reading to the yellow side reading.

If this is OK you'll need to measure some voltages around the regulator IC2. I'll see if I can extract my unit from the loft and make similar measurements.

Keith

Station X · 20th Jan 2016, 8:58 am

Quote:

Originally Posted by cxaaron

Hi, used to swapping out bad components but never had to diagnose a problem with power up before. So i measured resistance on the continuity setting, on the red side of the transformer across ways brown to blue wire with a reading of 011, and on the opposite side, yellow it read 1004. Test was done with the unit unplugged from the wall with power switch on, was this correct? thanks.

What were the units? Ohms?

cxaaron · 20th Jan 2016, 6:02 pm

Hi , using my DMM at the 2000 setting the readings were yellow side , primary 989r and the red side was 010r and across the mains blue to brown wire was 992r , hopefully these terms are expressed correctly . You mentioned about testing for voltages at ic2 is this something i can do?

KeithsTV · 20th Jan 2016, 9:33 pm

That looks as if the mains side is OK.

Next is a check on the DC supplies. With the meter on dc and mains applied to the unit measure the voltage across the large 1000uF capacitor C24. This should be 22 to 24V. If that's OK measure the voltage across the 10uF capacitor C25. This should be 15V.

Also as Michael says the lamp should light up if it doesn't it could be open circuit.

I should be able to find my unit tomorrow for comparison.

Keith

cxaaron · 21st Jan 2016, 6:21 pm

Hi, thanks for the help. C24 measures 25v and C25 measured 16.7. Across the transformer on the primary side I get a reading and a continuity tone on the yellow side I get a reading but not a continuity tone is this usual?

KeithsTV · 21st Jan 2016, 10:07 pm

The mains transformer is OK then. The 16.7V is a little high for the output of the 15V regulator. However that proves the PSU is functional.

The yellow side is the primary and with a resistance of around 1000 ohms will not give beep on a continuity tester. These only give a tone if the resistance is a few 10s of ohms.

I've just checked my unit and the bulb has failed but the regulator output is OK at 15.3V. I did find that the resistance across the mains lead was very high but operating the switch a few times brought that down to around 1000ohms. it's understandable as the unit hasn't been powered up for over 30 years.

I'm going to go through the set up procedure again as when I built it I didn't have much test equipment available but now I have suitable equipment. Before I do that I'll check the original WW articles.

Keith

Stevie342000 · 21st Jan 2016, 10:15 pm

Very interesting I just took a look at the WW Article earlier in the thread. I was shocked when I saw the picture. As I have 2 of these or a very similar unit not by Wireless World but by Kellar KDB-1.

I am wondering if there is a relationship between the two companies. The Kellar is listed in the 1970 Hifi Year book. I have a set of instructions some where and the calibration tape to set it up.

cxaaron · 21st Jan 2016, 11:35 pm

Hi, could it be that it's working but the bulb is not lighting?
I did plug a signal into the back to see if the vu meters would move, and tried the calibration tone to see if the vu meter would operate, but no luck. The power switch does not look in great shape even though it passed continuity across ways brown to brown and blue to blue.

Michael Maurice · 23rd Jan 2016, 10:44 am

Quote:

Originally Posted by cxaaron

The power switch does not look in great shape even though it passed continuity across ways brown to brown and blue to blue.

Quote:

Originally Posted by cxaaron

C24 measures 25v and C25 measured 16.7. Across the transformer on the primary side I get a reading and a continuity tone on the yellow side I get a reading but not a continuity tone is this usual?

That exonerates the power switch, and everything on both sides of the transformer.

cxaaron · 23rd Jan 2016, 11:19 pm

Thanks , looking through the above scanned pdf would i be right to think that i should try and replace IC2 ? or if the lamp is blown would this stop the unit from powering up ?

19th Jan 2016, 9:19 pm	#1
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Wireless World noise reducer This unit was avaliable in kit form in the mid seventies but it does not power up. The power switch and the cables from the plug and fuses all test good for continuity. I'm kind of a beginner but have a little knowledge and would like to know what to test next. There are no valves in this unit. Thanks .

19th Jan 2016, 9:52 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Wireless World noise reducer Can you post a circuit please. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

19th Jan 2016, 10:13 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: Wireless World noise reducer From memory this was based on Dolby circuits and was sold by one or two of the WW advertisers. ed

19th Jan 2016, 10:24 pm	#4
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,574	Re: Wireless World noise reducer I built one of these units when it came out and have the articles and the information that came with the kit. I'll see if I can find it and scan it. I've also still got the unit up in the loft. Keith

19th Jan 2016, 10:27 pm	#5
ajs37 Heptode Join Date: Jun 2003 Location: Bristol, UK. Posts: 900	Re: Wireless World noise reducer yes - Integrex sold them - I built one which I probably still have in my garage - worked very well - can't remember much about it though (it was over 30 years ago!) - circuit diagram would certainly help. Andy

20th Jan 2016, 12:15 am	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Wireless World noise reducer The bit to be careful about is that the kit will include a pair of specially selected FETs which are probably irreplaceable now as I doubt anyone now knows what characteristic they were selected for. The circuits, as I remember were by Dolby labs who were happy with private construction and supplier the FETs. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

20th Jan 2016, 12:35 am	#8
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,225	Re: Wireless World noise reducer Looking at that diagram, if its completely dead, then it can only be the mains cable, fuse, switch, transformer. Unless the bulb is open circuit it should light up __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

20th Jan 2016, 12:49 am	#9
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Re: Wireless World noise reducer Hi, used to swapping out bad components but never had to diagnose a problem with power up before. So i measured resistance on the continuity setting, on the red side of the transformer across ways brown to blue wire with a reading of 011, and on the opposite side, yellow it read 1004. Test was done with the unit unplugged from the wall with power switch on, was this correct? thanks. Attached Thumbnails

20th Jan 2016, 1:10 am	#10
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Re: Wireless World noise reducer Thanks Keith for scanning the file, you're very kind.

20th Jan 2016, 8:28 am	#11
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,574	Re: Wireless World noise reducer That looks as if the transformer is OK. The yellow side is the primary. Can you measure the resistance across the mains lead (brown and blue) at the 13A plug with the power switch in the on position. This will check the mains lead, power switch and fuse. You should get a similar reading to the yellow side reading. If this is OK you'll need to measure some voltages around the regulator IC2. I'll see if I can extract my unit from the loft and make similar measurements. Keith

20th Jan 2016, 6:02 pm	#13
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Re: Wireless World noise reducer Hi , using my DMM at the 2000 setting the readings were yellow side , primary 989r and the red side was 010r and across the mains blue to brown wire was 992r , hopefully these terms are expressed correctly . You mentioned about testing for voltages at ic2 is this something i can do?

20th Jan 2016, 9:33 pm	#14
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,574	Re: Wireless World noise reducer That looks as if the mains side is OK. Next is a check on the DC supplies. With the meter on dc and mains applied to the unit measure the voltage across the large 1000uF capacitor C24. This should be 22 to 24V. If that's OK measure the voltage across the 10uF capacitor C25. This should be 15V. Also as Michael says the lamp should light up if it doesn't it could be open circuit. I should be able to find my unit tomorrow for comparison. Keith

21st Jan 2016, 6:21 pm	#15
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Re: Wireless World noise reducer Hi, thanks for the help. C24 measures 25v and C25 measured 16.7. Across the transformer on the primary side I get a reading and a continuity tone on the yellow side I get a reading but not a continuity tone is this usual?

21st Jan 2016, 10:07 pm	#16
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,574	Re: Wireless World noise reducer The mains transformer is OK then. The 16.7V is a little high for the output of the 15V regulator. However that proves the PSU is functional. The yellow side is the primary and with a resistance of around 1000 ohms will not give beep on a continuity tester. These only give a tone if the resistance is a few 10s of ohms. I've just checked my unit and the bulb has failed but the regulator output is OK at 15.3V. I did find that the resistance across the mains lead was very high but operating the switch a few times brought that down to around 1000ohms. it's understandable as the unit hasn't been powered up for over 30 years. I'm going to go through the set up procedure again as when I built it I didn't have much test equipment available but now I have suitable equipment. Before I do that I'll check the original WW articles. Keith

21st Jan 2016, 10:15 pm	#17
Stevie342000 Hexode Join Date: Jan 2006 Location: Greater Manchester, UK. Posts: 373	Re: Wireless World noise reducer Very interesting I just took a look at the WW Article earlier in the thread. I was shocked when I saw the picture. As I have 2 of these or a very similar unit not by Wireless World but by Kellar KDB-1. I am wondering if there is a relationship between the two companies. The Kellar is listed in the 1970 Hifi Year book. I have a set of instructions some where and the calibration tape to set it up.

21st Jan 2016, 11:35 pm	#18
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Re: Wireless World noise reducer Hi, could it be that it's working but the bulb is not lighting? I did plug a signal into the back to see if the vu meters would move, and tried the calibration tone to see if the vu meter would operate, but no luck. The power switch does not look in great shape even though it passed continuity across ways brown to brown and blue to blue.

23rd Jan 2016, 11:19 pm	#20
cxaaron Pentode Join Date: May 2011 Location: Buxton, High Peak, Derbyshire, UK. Posts: 170	Re: Wireless World noise reducer Thanks , looking through the above scanned pdf would i be right to think that i should try and replace IC2 ? or if the lamp is blown would this stop the unit from powering up ?