|
Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
|
Thread Tools |
3rd May 2020, 11:27 am | #1 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
|
Hunts CRB3
Collecting my CRB3 is obviously on hold at the moment. In the meantime I have been tidying up a copy of the schematic. The next part of the process is to add component values. I did find a drawing that that had them added but many of the values measured rather than standard.
Does anyone have a components parts list that I could have? I will post the completed diagram for everyone to use. I may also have one two extra questions that need clarifying. Al
__________________
I won't tell you how I discovered that. |
3rd May 2020, 11:59 am | #2 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,118
|
Re: Hunts CRB3 parts list
I have this annotated circuit diagram.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley) |
3rd May 2020, 12:11 pm | #3 |
Pentode
Join Date: May 2017
Location: Ware, Hertfordshire, UK.
Posts: 215
|
Re: Hunts CRB3 parts list
if it uploads the info is on the forum 2017
|
3rd May 2020, 12:20 pm | #4 |
Pentode
Join Date: May 2017
Location: Ware, Hertfordshire, UK.
Posts: 215
|
Re: Hunts CRB3 parts list
that may be the wrong photo
|
3rd May 2020, 12:28 pm | #5 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
|
Re: Hunts CRB3 parts list
Thanks chaps. Alas both of those drawings are for an earlier model.
I have attached an untouched copy of the CRB3 schematic. Al
__________________
I won't tell you how I discovered that. |
3rd May 2020, 10:09 pm | #6 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,853
|
Re: Hunts CRB3 parts list
Hi!
If anyone who's got a CRB3 can email me high Res photos of the internals I can marry up the components with the diagram and redraw it! I tried getting one myself but some clot bid over £400 for it and no EM34 in it either – it had been substituted with a 1629 12.6V eye out of surplus somewhere! Chris Williams
__________________
It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! |
3rd May 2020, 10:20 pm | #7 |
Octode
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 1,177
|
Re: Hunts CRB3 parts list
I have an early CBR3, serial number 147, if anybody would like pictures and part references etc.
|
4th May 2020, 9:11 am | #8 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
|
Re: Hunts CRB3 parts list
Oldtechfan, how easy would it be for you put values beside each component reference?
Al
__________________
I won't tell you how I discovered that. |
4th May 2020, 9:25 am | #9 |
Heptode
Join Date: Aug 2009
Location: Carshalton, Surrey, UK.
Posts: 734
|
Re: Hunts CRB3 parts list
Hi,
I do have one of these, but can't get to it because of lockdown related things.. It is going to need repairing and re capping at some point... Any additional info would be most useful. they are deceptively simple I think.
__________________
Regards Peter B |
4th May 2020, 9:32 am | #10 |
Octode
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 1,177
|
Re: Hunts CRB3 parts list
|
4th May 2020, 10:39 am | #11 |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,737
|
Re: Hunts CRB3 parts list
As far as I can determine, the most comprehensively updated circuit is that by forum member Ron Bryan, dated 13 November 2017.
It's attached here it it's any help. (I don't have a CBR3).
__________________
David. BVWS Member. G-QRP Club member 1339. |
4th May 2020, 11:47 am | #12 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,205
|
Re: Hunts CRB3 parts list
Alistair's diagram is the one.
Some pictures from a CRB3 undergoing refurbishment: |
4th May 2020, 11:54 am | #13 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,205
|
Re: Hunts CRB3 parts list
and some more:
A few component values: R1 = 150 ohms R3 = 500 ohms 1% hi-stab R11, R12 = 1M R3 = 4M7 |
4th May 2020, 12:32 pm | #14 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,205
|
Re: Hunts CRB3 parts list
I tried to edit the above post but it timed out, here is the updated text:
and some more: A few component values: To large pot: R1 = 150 ohms 0.5W R3 = 500 ohms 1% hi-stab Around magic eye valveholder: R11, R12 = 1M R3 = 4M7 1x 0.01uF 1000V On large tag board: 2x 1k2 3W 1x 10k 3W 5x 68k 3W 1x 200pf 1% SM 1x 0.02uF 1% SM 1x 2uF 250V MKA On small tag board: 1x 50 ohms 1% hi-stab 1x 5k 1% hi-stab 1x 500k 1% hi-stab 1x 68k 3W 1x 33k 3W 1x 27k 3W 1x 0.47uF 250F The 3W types were originally carbon, probably 2W rating On switch: 2k2 3W Welwyn wirewound Large pot (measurement): Colvern CLR 6040/13 5000 ohms G Small pot (power factor): Colvern CLR 5001/11 1000 ohms PSU capacitor = 16 + 16 uf, 500V The Selenium rectifier will be replaced with a 1N5407 plus series resistor,value to be determined. The flying mains lead has been replaced with an IEC socket, the panel and chassis being punched accordingly. Last edited by m0cemdave; 4th May 2020 at 12:41 pm. |
4th May 2020, 12:33 pm | #15 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
|
Re: Hunts CRB3 parts list
All gratefully received.
I don't want to post the whole diagram yet as it is incomplete. I have attached a snippet to show what the finished article should look like. Al
__________________
I won't tell you how I discovered that. |
4th May 2020, 12:42 pm | #16 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,205
|
Re: Hunts CRB3 parts list
Alistair - I have just removed the reference to C6 on the valveholder, it may be C4 ! Apologies...
|
4th May 2020, 1:12 pm | #17 |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,737
|
Re: Hunts CRB3 parts list
Thanks Dave - I see that the circuit I posted was for the 1945 version whereas the one under discussion is the 1953 version.
Quite a comprehensive Operating Manual, which includes the circuit, as in Alistair's post, with the blue Biro cross on the switch wafer with C4 above. (Not sure what that's intended to indicate). Rather a pity that Hunts didn't annotate the component values and tolerances on the circuit, but that said, I guess that anyone restoring a CRB3 can see the values marked on the existing components anyway. An expensive instrument in its day no doubt, and an interesting piece of Test Gear 'archaeology', worthy of restoration.
__________________
David. BVWS Member. G-QRP Club member 1339. |
4th May 2020, 1:31 pm | #18 |
Nonode
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
|
Re: Hunts CRB3 parts list
Dave, re your comment "The Selenium rectifier will be replaced with a 1N5407 plus series resistor,value to be determined" in post #14.
The marked up diagram I referred showed an extra resistor in series with the rectifier as shown in the attachment. The value was marked as 1k4. The fact that it was a measured value makes me think that it was an original fitment. Perhaps it is only in later or earlier versions. Al
__________________
I won't tell you how I discovered that. |
4th May 2020, 3:30 pm | #19 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,205
|
Re: Hunts CRB3 parts list
Thanks Alistair, I will use that as a starting point when I put it back together.
And thanks to David for the full manual. |
4th May 2020, 8:37 pm | #20 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,853
|
Re: Hunts CRB3 parts list
Hi!
If you fit 5 X 68k resistors on the large tag board, you'll not get the magic–eye to light if they're R14 to R18 as I suspect them to be! A picture I found on Google "images search" shows them clearly identified with a RED spot using the obsolete "body–tip–spot" coding, hence 6k8 2W! I am draughting a new "Newnes quality" circuit diagram from Hunt's ghastly mess and it should be ready 2mrw afternoon! Chris Williams
__________________
It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! |