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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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16th Jul 2005, 7:01 pm | #1 |
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EKCO TS1105 CRT, transformer oil, etc
Hi,
I want to repair my TS 1105 with the broken tube I got from ebay. The most importand thing I am searching for is the CRM 92. A pin of the LOPT was broken and transformer isolation (PCB) oil was running out. I opend the soilder point on an other pin and this makes it possible to empty it compleately and refill it with PCB free transformer oil. I hope to find a source for a small quantity of oil next week. I have the trader sheet Nr.980 but it is TV only. Does anyone have the schematic of the radio? Or a complete schematic for me? Kind regards Darius |
17th Jul 2005, 10:19 am | #2 |
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Re: EKCO TS1105 ...need your help - please
Hello Darius,
Your EKCO TS1105 was a very common model from a whole series of sets based on the Ekco TS88 series. It was fix tuned to the London Alexandra Palace transmitter and used a TRF circuit. It is an odd set using a mixture of Mullard valves in the radio, H.T. and boost diode cicuit positions. A gas thyratron is used as frame generator, a throw back to pre war days. This was very unusual due to EKCO being contracted to Mazda to supply all their valve requirements. Mazda manufactured first class valves but the television range was very limited and dated and the only 100 m/a radio range at that time were the rather large Mazda octals. Mind you considering the size of the chassis they had room for these underneath! The chassis looks much older than its date of manufacture [1949] The radio section is a simple 'short' superhet using UCH42, UAF42 valves in a simple preset tuned arrangement. The sound output valve is a 10P13 [Mazda] that is very similar to the UL41. The sound output stage is used for both radio and television. The television only versions use a 6P25 [EL33, 6V6 etc] as output. Pity about the CRM92. They are very difficult to find these days. The entire range of MAZDA 2volt triodes had a short life due to heater cathode shorts or low emssion and many sets were scrapped due to this in the mid to late 50's, hence the lack of them now. If all fails you will find that most 9" tubes will fit the set but you will have to change the tube socket, [base] if its a tetrode, supply a first anode potential [easy] and maybe fit an ion trap magnet. Heater supply will have to be modified but the TS88 has 2V, 4V, and 6.3v available at the mains transformer. Just check the neck diameter and make sure the scan coils fit. I have a circuit SOMEWHERE for the version with radio but its not to hand. If you are still stuck I will enter the damp caves and se if I can find it. Regards JOHN |
17th Jul 2005, 3:02 pm | #3 |
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Re: EKCO TS1105 ...need your help - please
Hi John,
I got the schematic via email, thanks. Yes it is an interesting set with nice valves. That is why I bought it. I have never seen a triode CRT before and it is really a desaster for me that it is destroyed. The line output valve is a mazda 6P28. It is a good looking "koke bottle". I fixt the bakelite base with epoxy and tested it like a EL38 and it is very good! The sound output is a 6P25. First look I thaught it is gasy, because there is no getter on the top. The getter is small on one side. I'll take some pics for you soon. I often changed oil in my car. This is the first time for me to change oil in a TV set BTW the T1105 is Birmingham. It has not much RF stages and it seems there was a preamp for it avalible. Enough for now, Kind regards Darius |
18th Jul 2005, 6:58 am | #4 |
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Re: EKCO TS1105 ...need your help - please
Good morning John,
Yes you are right with the audio valve. I've looked at the trader sheet TV only. Hi Ed, I'll do so if it is PCB free! There is "Isolier 72" available but this is syntetec oil and can not be mixed with the old oil. I got a phone number at the electricity supply I'll try out today. Kind regards Darius |
18th Jul 2005, 9:14 am | #5 | |
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Re: EKCO TS1105 ...need your help - please
Quote:
I don't think there is a problem mixing synthetic and mineral oils. I think the synthetics are the same composition as mineral. I think the problem you are concerned about is using vegetable based oils in mineral based applications and vice versa. Its not the mixing of the oils that is the problem it's the composition of rubber seals that you need to worry about. So you need to replace the old oil, mineral with mineral or vegetable with vegetable. I don't know but I strongly suspect that transformer oils are all mineral. Kind regards, Peter. |
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19th Jul 2005, 11:51 am | #6 |
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Re: EKCO TS1105 ...need your help - please
Gidday to all of you, it is done.
I filled the empty lopt with nitrogene to replace conterminated air. First I tested mixing the old and new oil and I was successfull. Then I filled the lopt with the JA10 oil. After I finished it, I measured at all pins. One pin was not connected- shock- but this was earth puh! In the pics attached you can see the datasheet of the oil and the filling process. BTW the oil is stored in nitrogene to make sure that it is not conterminated with moist. Making it hot can "crack" the oil, the lady there toled me. Kind regards Darius |
21st Jul 2005, 8:51 pm | #7 |
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Re: EKCO TS1105 ...need your help - please
Good evening,
I have sound now, the radio works (BBC4 pos."1") and TV sound (Birmingham channel). The sound output valve is ok. First I thaught it is gasy. The Mazda valves are a good quality! John, the 6P28 is a beauty. The UY41 was gasy (Mullard!) and I took a new one. Without heating and volume max in pos. "V" it had 10V DC at g1. The katode resistor changed to 200 Ohms (390 Ohms.) I am not able to repair this resistor and replaced it. It seems I was able to rescue all caps including the electrolytics. The contrast poti will be replaced by NOS tomorrow. I hope this is all. The lopt is ok, I tested the V and H deflection ok. If someone has a CRM 92 please let me know. I have never seen this strange areal connector. Do you have one for me? Kind regards Darius Last edited by oldeurope; 21st Jul 2005 at 8:55 pm. Reason: text and picture |
22nd Jul 2005, 9:55 pm | #8 |
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Re: EKCO TS1105 ...need your help - please
Hello again,
The aerial input socket is indeed the original type used on car radio untill recent years. The familiar co-ax socket was introduced in 1948 and one of the first sets to use it was the BUSH TV12 of 1949. Don't worry too much if the 6F1's are a bit low emission. They will provide more than enough gain with your modulator. The U24 is an early EHT rectifier designed for flyback or R.F. eht supply. Its heater is powered from a small highly insulated winding on the mains transformer and on the whole is a reliable valve. It can be replaced if only as a temporary measure by a U25 or U26 providing the necessary base modifications are carried out. Mazda valves are of good repute but as mentioned earlier were somewhat 'behind the times' for the period. The gas thyratron 6K25 may cause frame 'bounce' when you finally get a picture on it! I suggest you replace the 'wax' capacitors one at a time switching on between replacements so that you can track your work. You WILL get it working. EKCO receivers are easy to get going due to the use of good transformers and major components. Failures are rare. Good luck with it Darius and keep us informed. Picture is my TRC138 chassis JOHN. |
24th Jul 2005, 5:49 pm | #9 |
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Re: EKCO TS1105 ...need your help - please
Good evening,
Heatercathodeshort wrote: "Mazda valves were very reliable but somewhat out of date. The 6P28 is similar to the Mullard EL38 but much 'fatter'." The EL38 is a pentode and the 6P28 is a beam power tetrode. The saturation voltage is lower and the efficiency of the line output stage is better. The EHT circuit is very clever! The Heaterwinding on the mains transformer is the EHT cap and makes sure that the U24 gets exactly 2V for its heater. So H-width adjusting and aging of the valves causes no change in the heater voltage! The problem with the tetrode CRT's (7BP7) is that you need a g2 voltage. I connected the g2 via a resistor to HT and reduced the plate voltage of the vision output valve by adding a resistor to ground. There is no positive booster voltage. Kind regards Darius |
24th Jul 2005, 6:11 pm | #10 |
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Re: EKCO TS1105 ...need your help - please
...Here a few pics of the provisorial mounting of the 7BP7.
Kind regards Darius |
24th Jul 2005, 6:13 pm | #11 |
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Re: EKCO TS1105 ...need your help - please
Hello again Darius,
You are quite right about the 6P28 of course. I was comparing it to the EL38 as its contempory rather than equivalent as such. Most early flyback eht systems powered the heater of the rectifier from the mains transformer. The problem was that most early flyback circuits and tramsformers just about scanned the tube let alone had enough power to feed the heater of the rectifier. The introduction of the wired in low consumption U25 and its 6.3v Mullard eqivalent the EY51, together with 'ferroxcube' transformer cores, greatly increased efficiency. Mazda produced a good range of R.F. pentodes such as the 6F1 but lacked sadly in the rectifier stakes. Most suffered from flaking cathodes and flash over and the early boost doides such as the U281/282 suffered an early death. The Mullard PY31 soldiered on for ever. Its great to see a picture on the beast! Tetrode tubes require less focussing field than a triode. Try placing a couple of strips of thin steel from back to front on the focus magnet. These will form a 'shunt' and may bring it into focus. Has your set still got the vertical steel rod mounted alongside the crt bowl? It was put there to balance stray magnet fields and straighten the picture ! Mine has no effect if removed! Regards. JOHN. |
25th Jul 2005, 5:43 pm | #12 |
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Re: EKCO TS1105 ...need your help - please
Good evening,
Hi John "Has your set still got the vertical steel rod mounted alongside the crt bowl? It was put there to balance stray magnet fields and straighten the picture ! Mine has no effect if removed!" Hmmm I don't know please look at the picture attached. Michael toled me to open the screw that fixes the focus adjustment. So I got a good focus but now I reached definatly the limit. I don't want to change much, because I am still hopefull to get a replacement tube. Did you disassamble a lopt of this set? Do you know how the lopt looks inside? Question in the RF bandfilters: In the sound RF, one core was between the coils. (wrong!!!) I tuned the filter and noticed that they used non magnetic metall cores and ferrite cores. At VHF ferrite is unusual. Is this normal in this set? The Q of the ferrite cores is much lower. My PYE LV20 uses only metall cores and I like this. Next time I'll sweep the vision and sound RF stages. But I think they don't need an aglyment. Kind regards Darius |
26th Jul 2005, 3:40 pm | #13 |
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Re: EKCO TS1105 ...need your help - please
Gidday,
Heatercathodeshort wrote: "You mentioned that you were using yours on a Channel 4 Birmingham, Sutton Coldfield modulator. It may be that your set was 'unofficialy' modified to receive channel 4, hence your odd core positions." John, the TS1105 is definatly a ch4 set. Now I know whats going on here ! Maybe you noticed in the testcard C that there is something wrong in the RF aglyment. In the pic attached you can see that the bandwith is too small. The fault was made by a british serviceman. He noticed that the set was misstuned, but he compensated this by replaceing the brass core by a ferrite one. C36 and C11 in trader sheet 980 caused the misstuning. Damping at this point causes a higher frequency and a ferrite core compensates this. I made new ( it's M6) brass cores and I am on the way to repair it. I think not much people know this fault and for the aglyment you need special instruments and knowledge. Forgett the agliment instructions in the trader sheet! Getting a picture is easy but getting a good picture is very much work! Kind regards Darius |
30th Jul 2005, 10:07 am | #14 |
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Re: EKCO TS1105 ...need your help - please
Good morning,
thanks to Heatercathodeshort (John) for the idea with the thin steel. I made steel (from a cany box) around the magnet and now the focus is ok. In the pics attached you can see how it is done and the aglied vision RF. Kind regards Darius |
31st Jul 2005, 7:37 pm | #15 |
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Re: EKCO TS1105 ...need your help - please
Hi Darius,
Following investigations I have discovered that the TS105 London chassus was produced with an extra '1' in the model number for the Birmingham frequency. [TRF] As further transmitters opened a superhet R.F. was fitted to the TRC124 series and the rare T141 set. I used the focus shunt trick in 1961 when I fitted a Brimar C12B crt in an old DEFIENT set fitted with the Plessy MK 1 chassis that I carried home from a jumble sale. I was still at school at the time but the picture was brilliant. Regards John. |
2nd Aug 2005, 7:48 pm | #16 |
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Re: EKCO TS1105 ...need your help - please
Hello again Darius,
This Ekco TS1105 is certainly an interesting one. The CRM93 is as you say an aluminised tube and is designed to work at a much higher EHT voltage than the old triode CRM92. It was used in the Ekco TMB272 portable and gives a brilliant picture in that set. It will work in the TS1105 [with a 1st anode potential] but with reduced performance. The TS chassis is not capable of providing much more than 6kv at the most. It will require an ion trap as it has a 'bent' gun assembly. Akuminised tubes are provided with ion burn protection by way of the micro aluminium screen backing but were still provided with ion traps to satisfy the buying public that had seen ion traps as a 'must have' when buying a new television. The non aluminised MW22-18 is a better bet. Regards. JOHN. |
5th Aug 2005, 7:49 pm | #17 |
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Re: EKCO TS1105 ...need your help - please
Ho again Darius,
The TS1105 like many other sets using the Mazda television range of valves of this period, uses the gas thyratron 6K25 as frame generator. They were quite difficult to stabilize and differed considerably in consistancy between valves. Your pictures show a very good scan considering the circuit. Another new 6K25 might improve the interlace but I doubt if owners of these sets would have noticed the defect as such. Regards JOHN. |
10th Aug 2005, 12:12 pm | #18 |
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Re: EKCO TS1105 ...need your help - please
Gidday,
back to the interlace problem and the H hold that triggers on both edges of the sync. The problem is fundamental. Please look at the schematic. L14 "rings" at the negative and positive edge. This generates a H trigger at both edges.. The V sync is not separated. The composite sync goes via C25 to R59. There is no DC component at R59. The small H sync pulses generate negative pulses. They don't trigger V 15. The long H pulses during the V- sync generates positive pulses, the first one should trigger V15. The problem for me is that the H puls triggers V15 and not the V pulse. I solved the problem in the following way. During the V pulse the current in V6 is higher because the H pulses during the V puls are longer. This charges the coil with magnetic energie. I added a cap to the coil. The cap is big 22nF and makes sure that the coil can not discarge during the positive pulses in the V sync. After the V sync it generates a positive pulse. This pulse triggers the 6K25 V15. Now I have a perfect interlace. I increased the plate resistor at V6 to 39K Ohms (I have an english 39K). This causes a fast falling edge and a slow rising edge. The triggering for the miller transitron V7 is much better now. Kind regards Darius |
17th Aug 2005, 3:54 pm | #19 |
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Re: EKCO TS1105 ...need your help - please
I wonder how the other two offset guns would work?
I tried them (of course), but there was no picture. Caused by the magnetic focus, the position of the electron gun is importand for the position of the picture. I played with magnets and got success. With to magnets it is possible to get a picture from the other guns too. Now I know why color tubes are static focused. BTW the regunner connected the focus internally to anode. So I need the focus magnet. In this electron gun every g1 and g2 has its own pin. Kind regards Darius |
18th Aug 2005, 6:08 pm | #20 |
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Re: EKCO TS1105 ...need your help - please
Good evening,
the EKCO TS1105 is nearly finished. How do you like it? Kind regards Darius |