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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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11th Mar 2008, 2:48 pm | #1 |
Retired Dormant Member
Join Date: Mar 2008
Location: leeds
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Vidor CN426 HENLEY
Hello All
I am a beginner and trying to get this set working. At the moment it is totally dead, no crackles from wavechange switch. I am puzzled as to why the HT is very high, ie 116v on the anode of DL94 all other anode volts are also very high. I have tried the valves in another set and they work ok. I get a crackle from the speaker when i flash a battery across the o/put transformer primary. any help would be much appreciated. |
11th Mar 2008, 3:42 pm | #2 |
Retired Dormant Member
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Re: Vidor CN426 HENLEY
Hi Dave
The HT for this set should only be 90Volts from a battery, if it is from a mains supply this is set to high, are all the valve heaters alight, though if the HT is to high the heater voltage might be as well. The various inter stage capacitors/resistors should be checked, one may be open circuit, ideally a I.F. signal should be injected to see if this gets through to the speaker, it could be the high HT is because the set isn't oscillating. A screwdriver tapped on the volume control tags should produce a crackle in the speaker to show the audio stage is working. Or a signal taken from here to another audio amp to show the R.F. I.F. is working if the fault is in the audio stage. Geof |
11th Mar 2008, 3:52 pm | #3 |
Nonode
Join Date: Dec 2002
Location: Coulsdon, Surrey, UK.
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Re: Vidor CN426 HENLEY
It sounds as though there is no supply to the valve heaters. These appear to be series fed from the HT line via ballast resistors. Check these are OK ( R19 /R20 ) If so, suspect a faulty contact in one of the valveholders interupting the heater chain... this can be tested by measuring ohms, with power removed, from the "low" side of R19 to chassis. If missing here, switch to "BATT" and do the same test from the LT + battery connection - there may be problems in the mains/Battery switching.
Andy |
11th Mar 2008, 4:18 pm | #4 |
Dekatron
Join Date: Sep 2003
Location: Bolton, Greater Manchester, UK.
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Re: Vidor CN426 HENLEY
If you can see a glow with these valves, you're seriously overrunning them. They should also come 'straight on'.
Does this set have series or parallel valve heaters? (I'm not at home, so not got a circuit handy.) Usually parallel, but sometimes series. Apart from the lower voltages and heaters being a bit different, they are like any other valve set. Get your avo and check valve heaters first. Then check to see whether each valve is receiving volts. Is the speaker and O/P transformer OK. Unlikely but possible. Cheers, Steve P.
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11th Mar 2008, 4:39 pm | #5 | |
Heptode
Join Date: Aug 2006
Location: Sheffield, South Yorkshire, UK
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Re: Vidor CN426 HENLEY
Hello Dave,
This set uses the following valves; DK92, DF91, DAF91, DL94 which are all battery types so there should be no visible glow to be seen from their heaters. If there is then switch off immediately! Steve's statement below is spot on; Quote:
Regards Last edited by Robert Darwent; 11th Mar 2008 at 4:47 pm. |
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11th Mar 2008, 6:33 pm | #6 |
Octode
Join Date: Oct 2005
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Re: Vidor CN426 HENLEY
I have several similar Vidor sets and when the heaters are running at the correct voltage (1.4v) you can just and just see a dull red glowing cord of light in a pitch dark room in the centre of each valve.
Cheers Lee
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11th Mar 2008, 6:42 pm | #7 |
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Re: Vidor CN426 HENLEY
It is difficult to determine if the valve heaters are working, a milliamp meter in the LT supply might be a better way to see if heater current is being drawn.
Geof |
11th Mar 2008, 6:48 pm | #8 | |
Octode
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Re: Vidor CN426 HENLEY
Quote:
Cheers Lee
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Lee |
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11th Mar 2008, 9:20 pm | #9 | |
Heptode
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Re: Vidor CN426 HENLEY
Quote:
Regards Last edited by Robert Darwent; 11th Mar 2008 at 9:27 pm. |
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11th Mar 2008, 10:31 pm | #10 | |
Retired Dormant Member
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Re: Vidor CN426 HENLEY
Quote:
Geof |
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12th Mar 2008, 12:44 am | #11 | |
Heptode
Join Date: Aug 2006
Location: Sheffield, South Yorkshire, UK
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Re: Vidor CN426 HENLEY
Quote:
Regards |
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12th Mar 2008, 4:46 pm | #12 |
Retired Dormant Member
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Re: Vidor CN426 HENLEY
Many thanks to all.
With your help I've traced a broken socket pin 1 in valve 3. When I poke it to make a connection the set now hums, no stations as yet but at least it's not totaly deaf. Will now change valve holder (bit of a fiddle!). Will let you know how I get on. Regards Dave |
12th Mar 2008, 6:56 pm | #13 |
Dekatron
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Re: Vidor CN426 HENLEY
Hi Dave
With some types of socket it is possible to change individual pins/contacts.
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12th Mar 2008, 9:35 pm | #14 |
Pentode
Join Date: Jul 2007
Location: Clophill, Bedfordshire, UK.
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Re: Vidor CN426 HENLEY
The heaters in the Henley are series connected for both mains and battery operation. Any open circuit heater will therefore stop all heaters working. With no heaters there is no anode current and with no anode current the HT voltage could easily rise to 115 volts. The easiest way to check the valve heaters is with an ohmeter (Digital or analogue). If all are OK then then clean the valve heater pins. If this does not solve the problem look at the valve bases (check for heater continuity on the valve base. Check the heater supply from the mains transformer and check the 2 parts of the metal rectifier (ohmeter should read high one way and low with the connections reversed). The other thing to check is the switch. From the rectifier there are two resistors in series (1.4K and 700, check for open circuit) and these then connect to the DL94 heater via the rotary switch (battery, off, mains). Check for switch closure (ohmeter) or temporarily short out the switch. Trader sheet 1155 has all the info you will need (on CD 1).
Hope this is useful. John |
13th Mar 2008, 2:06 pm | #15 | |
Heptode
Join Date: Aug 2006
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Re: Vidor CN426 HENLEY
Quote:
The valves are series connected in this set with the two filament halves of the DL94 also in series, not parallel as I stated previously. So a poor heater pin connection in any of the valves will obviously break the heater chain and stop all the valves from working. And it appears that is the case since Dave has now reported finding a broken pin clincher at pin 1 in one the sockets. Regards |
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3rd Apr 2008, 12:01 pm | #16 |
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Re: Vidor CN426 HENLEY
Hi all
Many thanks to all who helped. I have had to replace 10 of those little tuning fork shaped valve holder sockets, they where either broken or making poor contact, Iv'e gone right off McMurdo holders. The set now works fine, another bit of radio history repaired. Thanks again Dave |
3rd Apr 2008, 5:27 pm | #17 |
Nonode
Join Date: Dec 2002
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Re: Vidor CN426 HENLEY
Well done for your perseverance Dave !
Memories of multiple holder swap outs on my MB60 When you get to the third faulty holder, you do tend to question your sanity ! Luckily faith is restored on hearing the first sounds emanate from the set ,usually in several decades. Andy |
3rd Apr 2008, 5:58 pm | #18 | ||
Heptode
Join Date: Aug 2006
Location: Sheffield, South Yorkshire, UK
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Re: Vidor CN426 HENLEY
Quote:
Quote:
Yes well done for sticking with it. And I thought I'd been unlucky to have to replace 5 broken fork pins in my Vidor Vanguard! But like Andy has commented its all worth that effort to here a set working again like it should. Regards |
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