22nd Jan 2022, 11:41 am | #81 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,433
|
Re: Another TV22
Thanks John, I'll keep my attention focused in this area as it seems to be a general concensus that the fault remains in this part of the circuit. I have repaired two TV22s in the past one EF91 and the other an EF80 deck but they give no trouble in the repair and worked very well after. This set must have had a problem when it was in use all those years ago as the RF and aerial coils along with sound IF coils had all been messed around with. I can confirm the lead to my aurora is good, I made up a second one yesterday just to make sure so the fault remains with the set.
P.s. I don't use the flash on my camera, at this time of year especially we have a lot of bright sun directly through the front windows, it makes off screen photos incredibly difficult to photograph so I often have to wait until the evening! Cheers Bren |
22nd Jan 2022, 1:27 pm | #82 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
|
Re: Another TV22
Hi.
I pulled out my Frankenbush TV22 Today and fitted another CRT, it's been off for some time due to having a really bad CRT. This set has been considerably modified with, Thorn 950 Jellypot LOPT, stabilised EHT, Flywheel sync, blocking oscillator line generator, 30FL1 line osc/sync seperator, 30PL1 frame osc/output. 30FL1 video amp and cathode follower DC coupled to CRT cathode, isolated CRT heater supply, capacitive mains dropper and other refinements. It's a EF91 front end and is happy with 18db signal attenuation. It originally had the BUSH band 3 converter, its years since I removed it but I do remember there was a mod that had to be removed, but I completely forget what it was, if there is any info on what was required to do the mod make sure its fully reversed. The picture on this one is stunning.
__________________
Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
22nd Jan 2022, 5:23 pm | #83 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,433
|
Re: Another TV22
Hi Trevor
That's interesting, it would be useful to know if there were any service notes released for the fitment of the band III converter as despite looking for some I've never came across any. As far as I'm aware the wire to the contrast control is the only thing that needs replacing and it looks as though my RF deck is as per the schematic otherwise but sometimes things can be missed. |
22nd Jan 2022, 5:49 pm | #84 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
|
Re: Another TV22
This is the best I can do. Installation guide and circuit changes for the converter/tuner. J.
|
22nd Jan 2022, 6:17 pm | #85 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
|
Re: Another TV22
Make sure that the actual tuning cores in the front end RF tuning are actually moving within the coil formers. The oscillator looks ok as you appear to have a tuned test card providing of course it is tuned to the same channel as your converter..
Incorrect IF alignment should not cause such a loss of gain or display grain/mush so leave that well alone! You cannot reset this correctly without an ACCURATE signal generator. John. |
22nd Jan 2022, 7:37 pm | #86 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,433
|
Re: Another TV22
Thanks John, after you mentioned about the channel tuning, my aurora is currently set to channel 2 but the indicator on the tuning coil is sitting between channel 3 & 4, if I turn it back I can also tune in again at around channel 1 (aurora still on ch2) but the signal looks to be somewhat worse.
|
22nd Jan 2022, 8:13 pm | #87 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
|
Re: Another TV22
Ah ha.
If the scale is miles out then its likely that its not tracking properly. I'd slowly move the tuning control toward the correct marking for the channel you are on and follow it with the oscillator core adjustment. If the signal level goes up its just mistracking and a full and proper alignment will sort it out. The alignment table is in the TV servicing red books on page 117, 1951 I think. I'm all locked up, remember the page number but can't be sure of the year.
__________________
Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
22nd Jan 2022, 9:09 pm | #88 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,274
|
Re: Another TV22
Before you start a full re-alignment I would try screwing around with L3 and L4 the two cores adjacent to the channel selecting knob and easily accessible.
Peter |
22nd Jan 2022, 9:29 pm | #89 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,433
|
Re: Another TV22
I have previously adjusted L3 and L4 and the results I have now are the best I managed to achieve in doing so. If anyone is interested in taking the deck and investigating further I wouldn't mind posting it, that is providing you have a suitable TV22 to hook it up to. I think I'm probably getting to the limit of what I can do here at the minute as my scope is only a 20mHz and my advance E2 is awaiting new smoothing caps after they gave way some months ago. I hate to admit defeat with this but I don't think I'll be getting much further than where the set currently is.
|
22nd Jan 2022, 9:35 pm | #90 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,324
|
Re: Another TV22
Having been playing with a couple of TV24s today (same chassis as the '22) your image really does look like a tuning fault - one of the three tuning cores maybe not moving as suggested by Heatercathodeshort. But adjusting any of them will have an effect on sound and vision. If one doesn't do that then it's not moving in its former. (Apologies if you have done all this already.)
You can try the old tuning-wand method in the cores; a long thin bit of ferrite and a long thin brass bolt glued onto opposite ends of a wooden or plastic stick and gently poke them into the core to see what happens. If poking either ferrite or brass ends reduces gain then the core is likely peaked. Or if any matching tuning cap is o/c and tuning is way off anyway this trick probably won't make any difference. Worth a try on all the IF cores too. Of course it won't work it you can't get into the threaded cores because of wax (so if undisturbed should be close enough), but if someone has been in there already this technique will probably give you a clue - especially if you can get in at both ends of an inductor. I'm not sure the accuracy of the tiny 'scale' on one of the tuning knobs is anything to go by. |
22nd Jan 2022, 9:49 pm | #91 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,274
|
Re: Another TV22
If the IF cores are stiff give them a squirt of release oil.
Only make very small changes to test which direction gives less or more gain. Don't forget that there are slugs in both ends of each IF can. Peter Last edited by peter_scott; 22nd Jan 2022 at 10:06 pm. |
22nd Jan 2022, 10:18 pm | #92 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
|
Re: Another TV22
Hi Bren.
You are welcome to send it to me, you'd need to cover return costs of course. PM if interested, I'd update here and also put it on YouTube.
__________________
Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
23rd Jan 2022, 10:40 am | #93 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
|
Re: Another TV22
Nice offer Trevor. Unless the IFs have been twiddled, a first for a TV22, The fault must be in the first stage unless the oscillator is working on a harmonic.
providing you have returned the original connections for Band 1 operation my thoughts are on the tuning cores or broken wires to the aerial and anode coils maybe due to heavy cleaning. Just a thought. EF80, don't twiddle the IFs! They will screw up and cause a lot more unnecessary doom. Good luck with it, John. |
23rd Jan 2022, 8:05 pm | #94 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,433
|
Re: Another TV22
Firstly let me say a huge thank you to all who have helped in the thread and to those who have offered to help, I've had a few PMs as well as Trevor's offer on there (thank you Trevor for the kind offer), it's very humbling to have such folk willing to share information and even offer help when others get stuck, I suppose that's what makes this forum so popular. Forum member Freya was first to offer to take a look via PM and I've agreed to send the chassis over to him for a fresh pair of eyes to investigate, hopefully we'll hear the diagnosis and subsequent rectification.
Let's hope my next project set isn't as bad as this and if this has taught me anything, some reading up of RF circuits would probably do me some good too. I have to admit it's one section I haven't shown much interest in over the years and some knowledge would certainly go a long way next time I find myself in a similar situation |
24th Feb 2022, 12:33 pm | #95 |
Octode
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,990
|
Re: Another TV22
Bren sent the deck to me last week,
Checking it over was straightforward and as Trevor, John and Peter had suggested, the problem was indeed due to the misalignment of the RF Anode coil which had been wound in most of the way, the L1 image rejecter trimmer coil was also incorrect, after an alignment procedure the deck now has good gain and bandwidth with the contrast control working over its entire range. A requested Belling & Lee style aerial connector completed the work. It will be on its way back shortly.
__________________
Stephen _________"It`s only an old telly" ___ |
25th Feb 2022, 12:09 am | #96 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
|
Re: Another TV22
Nice one Stephen and a good result.
__________________
Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
25th Feb 2022, 12:12 am | #97 | |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
|
Re: Another TV22
Quote:
I was wondering where the image with the 3 coils in the back of the RF deck is from. i don't thing I've ever seen it. Thanks Helder |
|
25th Feb 2022, 7:52 am | #98 | |
Hexode
Join Date: Jan 2011
Location: Düsseldorf, Germany.
Posts: 368
|
Re: Another TV22
Quote:
A capacitive mains dropper is not the worst you can do to a fine bakelite cabinet! Would you like to introduce your work here at this place? Thanx in advance! Regards, German Dalek
__________________
And now something completly different: MARC BOLAN, he was/is the real king of Pop Music! |
|
25th Feb 2022, 8:39 pm | #99 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,433
|
Re: Another TV22
I received the chassis back from Stephen today all safe and sound. In true style of this particular set it has decided to throw another hissy fit and something has been upset in the time it was last powered up. I have no illumination from the CRT but a brief shrinking raster when switching the set off. Usually I can get a blank raster visible just by turning up the brightness. Voltages on the base seem okay and there is EHT at the second anode so I'll do some poking around elsewhere. Hopefully once this is solved and thanks to Stephen's help I will be rewarded with a nice picture!
|
26th Feb 2022, 10:22 am | #100 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
|
Re: Another TV22
Check the A1 voltage. have you mucked about with the metrosil? The A1 decoupling cap is hidden behind a tag board, have you replaced it? Check EHT voltage, an EHT meter is essential when working with vintage receivers. Check CRT cathode and grid voltages. If all is OK the CRT may have gone a bit gassy but that is a long shot. John.
|