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Old 22nd Jan 2022, 4:43 pm   #1
Jimwall
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Default Zenith model 7J645T Valve Radio.

Can any body on the forum identify this old Zenith and would it be worth repairing i see there is one valve socket without a valve and i dont see much information on this on the internet also my pictures .
are little bit iffy
known faults power cord in bad state ,speaker blown (tasty. meal for a mouse)an 1 valve missing ,
cabinet and knobs all good
dialing cord off the V capacitor but not broken
is it worth fixing noting that parts in Za are scarce:
the lady who parted with it said invariably"" it used to work havent we all heard that statement before
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Old 22nd Jan 2022, 4:57 pm   #2
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Default Re: zenith model 7J645T Valve Radio

Only you can decide if it's worth fixing! One thing you have to be careful of is the pushbutton assembly. You have no idea what condition this is in and it would be sheer folly to fix everything and then find the pushbuttons are beyond repair.

Don't know much about Zenith but I think they have their origins in the USA. Might be worth checking out some US vintage sites and see if there is any info out there.
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Old 22nd Jan 2022, 4:59 pm   #3
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Default Re: zenith model 7J645T Valve Radio

All sets are worth restoring, this one with its rather lovely light wood case definatly. What are the valves in there, from those a good guess will be possible. Photo of the insides? Both over and under chassis.
 
Old 22nd Jan 2022, 5:04 pm   #4
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Default Re: zenith model 7J645T Valve Radio

more images from inside
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Old 22nd Jan 2022, 5:48 pm   #5
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Default Re: zenith model 7J645T Valve Radio

Looks a bit reclusive! Not in Radiomuseum nor Nostagiaair. Possibly a Za home market model? Style and octal valves suggest late '40s maybe early '50s.

The 3-gang tuning cap suggests a RF stage and the 6F6 output valve is not a popular one (only 24 sets in Radiomuseum use it)!
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Old 23rd Jan 2022, 12:29 am   #6
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Default Re: zenith model 7J645T Valve Radio

We can see that there is a 6F6GT audio output valve which is plugged into an Octal valveholder.

There are three Locktal valves which are fitted into different valveholders.

If you can find the markings on the Loctal valves and tell us if the missing valve is Octal or Locktal, we could make a guess as to the identity of the missing valve.

There seems to be three wires going from the chassis to the transformer mounted on the loudspeaker.
Do you have any means of checking the continuity of the windings in that transformer?

You could also check the windings of the mains transformer if it has one.
That tall box should contain either a mains transformer or some dropping resistors.
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Old 23rd Jan 2022, 12:59 am   #7
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Default Re: zenith model 7J645T Valve Radio

It's running an RF stage. At some point it must have been a pretty good wireless.
I agree about the push buttons, especially if this set has been a "bit dusted up".
Some pictures from underneath the chassis will help a lot.

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Old 23rd Jan 2022, 12:31 pm   #8
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Default Re: Zenith model 7J645T Valve Radio.

Thanks for the feedback so far much appreciated!i believe that the was a record player attached and a doctor in Jhb took that with the cabinet.nd i was offered the radio for 20 dollars!what I will do is carefully remove the chassis and try and take some images of the electronics underneath and forward them !I have never stripped or worked on this type of valve radio before so its looks compact enough to try and get some life out of this!interesting label says it was sold by Bradlows in Salisbury and Bulawayo Rhodesia
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Old 23rd Jan 2022, 12:39 pm   #9
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Default Re: Zenith model 7J645T Valve Radio.

Thought that I might have this circuit but no joy. I can say that the specific model is not in the following Rider Perpetual Trouble Shooter volumes; 1,2,3,5,6,11,13 and 17, as far as I can tell.

My guess is that it's in one of these volume numbers 10,12,14,15 or 16. Sorry I don't currently have them to check.

You might be able to check the index for these books online, at least that will tell you if it was included and which volume it's in.

Dave
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Old 23rd Jan 2022, 1:04 pm   #10
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Default Re: Zenith model 7J645T Valve Radio.

I wonder if it's loosely based on the Zenith 7J045T ?

Lawrence.
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Old 23rd Jan 2022, 3:41 pm   #11
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Default Re: Zenith model 7J645T Valve Radio.

The number of pushbuttons is the same and there's a mixture of Octal/Loctal valves so the front end (RF/IF) might well be similar. I wonder if that 6F6 is a cuckoo? The -045T has a triode-double triode P-P audio amp.

Some nice clear photos of the chassis, topside plan and under chassis would be helpful.
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Old 23rd Jan 2022, 6:10 pm   #12
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Default Re: Zenith model 7J645T Valve Radio.

Quote:
Originally Posted by ms660 View Post
I wonder if it's loosely based on the Zenith 7J045T ?

Lawrence.
Being a US radio collector, I'm familiar with the US makes, especially Zenith.
The "J" models were either export or dual source special models, used in areas that didn't have electric service, but pending.
The set appears to be a pre-1941 model. The model, 7J045 seems to be close. It's listed in Rider's 15.
The valve numbers are stamped on the socket face. It could be that the 6F6 valve was substituted for the 1J6G and the socket rewired. The original valve number should be stamped on the socket.
Even in the US, the 1J6G wasn't that common!
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Old 25th Jan 2022, 12:47 am   #13
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Default Re: Zenith model 7J645T Valve Radio.

I looked at the Rider Volume 15 pages 54 to 58 which can be viewed for free at worldradiohistory.com.

It refers to a model 7J045T on a 7C61T chassis.

It has 8 pushbuttons and a mains transformer incorporating a 6V vibratory converter.

The valve lineup is :- 7H7 RF stage, 6K8GT converter, 7B7 IF stage, 7C6 Detector & Amp , 6L5G driver, 1J6G audio output, 6X5GT rectifier.

The schematic and component data are included.
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Old 26th Jan 2022, 3:22 am   #14
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Default Re: Zenith model 7J645T Valve Radio.

Quote:
Originally Posted by Silicon View Post
I looked at the Rider Volume 15 pages 54 to 58 which can be viewed for free at worldradiohistory.com.

It refers to a model 7J045T on a 7C61T chassis.

It has 8 pushbuttons and a mains transformer incorporating a 6V vibratory converter.

The valve lineup is :- 7H7 RF stage, 6K8GT converter, 7B7 IF stage, 7C6 Detector & Amp , 6L5G driver, 1J6G audio output, 6X5GT rectifier.

The schematic and component data are included.
I'd like to see a clear photo of the top and the bottom of the chassis to see the valve sockets and with the power supply cover removed.
It's an interesting set and well worth restoring. The speaker can be replaced with a ordinary PM, 3-4 ohm speaker.
Dave, USradcoll1, always interested.
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Old 4th Feb 2022, 7:05 am   #15
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Default Re: Zenith model 7J645T Valve Radio.

OK the valve that is missing has these numbers imprinted on the case 6L5G the other two valve's are 7C6 and 6F6GTwhich are still there I haven't checked the others yet hopefully soon I will disassemble the chassis
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Old 4th Feb 2022, 11:58 am   #16
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Default Re: Zenith model 7J645T Valve Radio.

Is the socket for the 6F6GT marked as such? The 6L5G is the triode driver for a 1J6G double triode output in the 7J045T.

It may be that this set is similar to the 7J045T but with different output and power supply arrangements.
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Old 4th Feb 2022, 1:13 pm   #17
Jimwall
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Default Re: Zenith model 7J645T Valve Radio.

Thx Herald. OK the physical valve is a Mullard 6F6GT
Looking at the socket On the board Numbers printed are
1J6G
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Old 4th Feb 2022, 4:52 pm   #18
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Default Re: Zenith model 7J645T Valve Radio.

Ahhh.... someone's been at it, then! Maybe the 1J6G valve was unobtainium at some time. It's certainly an odd valve for a mains set with its 2V filament supply. Or perhaps its driver or output transformer failed.

The wiring round the valve socket would bear investigation at any rate.
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