HUNTS CRB Analyser. - UK Vintage Radio Repair and Restoration Discussion Forum

mike1 ryan1 · 12th Mar 2019, 6:57 am

Hi, can anyone provide me with component values for a hunts capacitor and resistor bridge tester. I have one that I bought some time ago that was in a bit of a mess inside. Somebody had made some modifications and butchered it a bit. I got a wiring diagram but there was no values with it. It works of a fashion but is not right. It would be handy to have it to test out a 20s or 30s radio I have and so I would like to get it working properly.
Thanks,
Mike

Andrewausfa · 12th Mar 2019, 8:46 am

Hi Mike,

Ron Bryan put together an updated circuit diagram here.

https://www.vintage-radio.net/forum/...d.php?t=141358

Andrew

mike1 ryan1 · 12th Mar 2019, 3:51 pm

That's fantastic thank you very much for that. That was so much easier than I thought it would be.
Thanks,
Mike

Andrewausfa · 12th Mar 2019, 5:15 pm

Mike,

Not sure of your experience but just keep an eye on the rectifier, the stick looking thing or J25 on Ron's diagram. Has the possibility of letting the magic smoke out.

Andrew

mike1 ryan1 · 13th Mar 2019, 3:04 am

I've replaced it with a diode the last time I had a go at it. There was a circuit diagram on the internet at the time but incorrect values on it amongst other mistakes. I gave up in the end I must admit. I was really pleased to find it so easy to get the details this time. Thank you though for the advice.
Mike

mike1 ryan1 · 14th Mar 2019, 9:20 am

Appreciate the advice though thanks

Mike

TowerRadio · 14th Mar 2019, 3:33 pm

Because of its age you should treat ALL the caps with suspicion,especially the one that feeds the grid on the indicator.Les.

mike1 ryan1 · 23rd Mar 2019, 10:33 pm

Just a question about replacing the rectifier with a diode, does it need a resistor in series with it to replicate the rectifier resistance?

avocollector · 23rd Mar 2019, 10:48 pm

Normally yes - the diode would normally give you a higher rectified voltage than the copper oxide/selenium rectifier - there is quite a bit of discussion on this on you tube (replacing copper/selenium rectifier) but I cannot find again the really good posting on this which I saw before and was a) simple b) showed you easily how to determine the new series resistor value. if I come across it again I'll post.

mike1 ryan1 · 23rd Mar 2019, 11:43 pm

Also is the target, pin 4, the small 'grid under the anode and the grid, pin 5, directly above the cathode. I only ask because this is how I wired mine and it doesn't work at all, no fluorescent glow from the valve at all.

Alistair D · 24th Mar 2019, 12:54 am

The official schematic for the CRB shows the rectifier with its cathode connected to earth. This the wrong way round. The updated schematic posted by Ron Bryan shows the anode connected to earth. This is the correct orientation.

Worth checking which way round yours is.

Al

mike1 ryan1 · 24th Mar 2019, 3:21 pm

Well I've checked and rechecked all the wiring and components, which have all been replaced and totally rewired, and tried another y63 but still won't flouresce. It comes on briefly as it warms up then goes off, as if it's when a capacitor charges up. One question is about the 1uf capacitor between the 190v winding and earth, should this be an electrolytic type? I replaced it with a non polarised type poly one as that was what was in it. When I got it someone had already tried to get it working and wired a few things up wrong. I can't find anything else that could be wrong.
Mike

mike1 ryan1 · 26th Mar 2019, 11:21 am

I've been looking at some images on Google of the insides of these and there does seem to be a large electrolytic capacitor which I assume is the 1uf one. I've ordered one and will try it and see.

ronbryan · 26th Mar 2019, 11:50 am

If a known good eye tube is not working, could you try measuring the voltages on the valve base with respect to chassis and post them here? You say that all the components have been checked, but does the rear wafer of the function switch supply HT to the Y63 anode and target when swiched to the appropriate measurement mode? It is also just possible that either the 1M target and 4M7 grid leak resistors go open when voltage is applied.

Swappping a HT smoothing film capacitor with an electrolytic of the same value will make no difference.

Ron

davebms · 26th Mar 2019, 11:54 am

Hello all.

I have a Hunts apart (work in progress) the 1uF capacitor I think is for HT smoothing, it was originally taped to the selenium stick, inside is a 2uF which connects to the power factor resistor. In my tester it's a Hunts 8801 whn in parallel with a .01/.01/.02. There is an old post on here that said that was done to get exactly 2uF, mine nearly works but is WAY off calibration!!

Dave.

mike1 ryan1 · 29th Mar 2019, 9:13 pm

Apologies for the delay I've been working. Here are the voltages as they appear on the back of the valve base. Hope someone can shed some light on my problem.
Thanks, Mike

ronbryan · 29th Mar 2019, 11:44 pm

Can you add the voltages that should have accompanied your posting #16, Mike.

Ron

mike1 ryan1 · 30th Mar 2019, 9:28 am

Oops forgot to attach the file.

mike1 ryan1 · 30th Mar 2019, 9:43 am

The switch position was 'S'. Is this high because of the diode being used in place of the rectifier?

mike1 ryan1 · 30th Mar 2019, 12:06 pm

Sorry this was in the 'R' position. I have since used a variable resistor to bring the voltage to 167 and it didn't make any difference

12th Mar 2019, 8:46 am	#2
Andrewausfa Octode Join Date: Dec 2010 Location: St Ives, Cambridgeshire, UK. Posts: 1,180	Re: HUNTS CRB Analyser. Hi Mike, Ron Bryan put together an updated circuit diagram here. https://www.vintage-radio.net/forum/...d.php?t=141358 Andrew __________________ Invisible airwaves crackle with life. Or they should do. BVWS Member

12th Mar 2019, 3:51 pm	#3
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. That's fantastic thank you very much for that. That was so much easier than I thought it would be. Thanks, Mike

12th Mar 2019, 5:15 pm	#4
Andrewausfa Octode Join Date: Dec 2010 Location: St Ives, Cambridgeshire, UK. Posts: 1,180	Re: HUNTS CRB Analyser. Mike, Not sure of your experience but just keep an eye on the rectifier, the stick looking thing or J25 on Ron's diagram. Has the possibility of letting the magic smoke out. Andrew __________________ Invisible airwaves crackle with life. Or they should do. BVWS Member

13th Mar 2019, 3:04 am	#5
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. I've replaced it with a diode the last time I had a go at it. There was a circuit diagram on the internet at the time but incorrect values on it amongst other mistakes. I gave up in the end I must admit. I was really pleased to find it so easy to get the details this time. Thank you though for the advice. Mike

14th Mar 2019, 9:20 am	#6
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Appreciate the advice though thanks Mike

12th Mar 2019, 6:57 am	#1
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	HUNTS CRB Analyser. Hi, can anyone provide me with component values for a hunts capacitor and resistor bridge tester. I have one that I bought some time ago that was in a bit of a mess inside. Somebody had made some modifications and butchered it a bit. I got a wiring diagram but there was no values with it. It works of a fashion but is not right. It would be handy to have it to test out a 20s or 30s radio I have and so I would like to get it working properly. Thanks, Mike Attached Thumbnails

14th Mar 2019, 3:33 pm	#7
TowerRadio Hexode Join Date: Mar 2008 Location: Bristol, UK. Posts: 388	Re: HUNTS CRB Analyser. Because of its age you should treat ALL the caps with suspicion,especially the one that feeds the grid on the indicator.Les.

23rd Mar 2019, 10:33 pm	#8
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Just a question about replacing the rectifier with a diode, does it need a resistor in series with it to replicate the rectifier resistance?

23rd Mar 2019, 10:48 pm	#9
avocollector Heptode Join Date: Jul 2010 Location: Wellington, New Zealand. Posts: 653	Re: HUNTS CRB Analyser. Normally yes - the diode would normally give you a higher rectified voltage than the copper oxide/selenium rectifier - there is quite a bit of discussion on this on you tube (replacing copper/selenium rectifier) but I cannot find again the really good posting on this which I saw before and was a) simple b) showed you easily how to determine the new series resistor value. if I come across it again I'll post.

23rd Mar 2019, 11:43 pm	#10
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Also is the target, pin 4, the small 'grid under the anode and the grid, pin 5, directly above the cathode. I only ask because this is how I wired mine and it doesn't work at all, no fluorescent glow from the valve at all.

24th Mar 2019, 12:54 am	#11
Alistair D Nonode Join Date: Jan 2010 Location: Edinburgh, UK. Posts: 2,008	Re: HUNTS CRB Analyser. The official schematic for the CRB shows the rectifier with its cathode connected to earth. This the wrong way round. The updated schematic posted by Ron Bryan shows the anode connected to earth. This is the correct orientation. Worth checking which way round yours is. Al __________________ I won't tell you how I discovered that.

24th Mar 2019, 3:21 pm	#12
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Well I've checked and rechecked all the wiring and components, which have all been replaced and totally rewired, and tried another y63 but still won't flouresce. It comes on briefly as it warms up then goes off, as if it's when a capacitor charges up. One question is about the 1uf capacitor between the 190v winding and earth, should this be an electrolytic type? I replaced it with a non polarised type poly one as that was what was in it. When I got it someone had already tried to get it working and wired a few things up wrong. I can't find anything else that could be wrong. Mike

26th Mar 2019, 11:21 am	#13
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. I've been looking at some images on Google of the insides of these and there does seem to be a large electrolytic capacitor which I assume is the 1uf one. I've ordered one and will try it and see.

26th Mar 2019, 11:50 am	#14
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,959	Re: HUNTS CRB Analyser. If a known good eye tube is not working, could you try measuring the voltages on the valve base with respect to chassis and post them here? You say that all the components have been checked, but does the rear wafer of the function switch supply HT to the Y63 anode and target when swiched to the appropriate measurement mode? It is also just possible that either the 1M target and 4M7 grid leak resistors go open when voltage is applied. Swappping a HT smoothing film capacitor with an electrolytic of the same value will make no difference. Ron Last edited by ronbryan; 26th Mar 2019 at 11:59 am.

26th Mar 2019, 11:54 am	#15
davebms Pentode Join Date: May 2017 Location: Ware, Hertfordshire, UK. Posts: 215	Re: HUNTS CRB Analyser. Hello all. I have a Hunts apart (work in progress) the 1uF capacitor I think is for HT smoothing, it was originally taped to the selenium stick, inside is a 2uF which connects to the power factor resistor. In my tester it's a Hunts 8801 whn in parallel with a .01/.01/.02. There is an old post on here that said that was done to get exactly 2uF, mine nearly works but is WAY off calibration!! Dave.

29th Mar 2019, 9:13 pm	#16
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Apologies for the delay I've been working. Here are the voltages as they appear on the back of the valve base. Hope someone can shed some light on my problem. Thanks, Mike

29th Mar 2019, 11:44 pm	#17
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,959	Re: HUNTS CRB Analyser. Can you add the voltages that should have accompanied your posting #16, Mike. Ron

30th Mar 2019, 9:28 am	#18
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Oops forgot to attach the file. Attached Thumbnails

30th Mar 2019, 9:43 am	#19
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. The switch position was 'S'. Is this high because of the diode being used in place of the rectifier?

30th Mar 2019, 12:06 pm	#20
mike1 ryan1 Pentode Join Date: Jan 2013 Location: Ulverston, Cumbria, UK. Posts: 115	Re: HUNTS CRB Analyser. Sorry this was in the 'R' position. I have since used a variable resistor to bring the voltage to 167 and it didn't make any difference