Featured
Latest
Share:
Notifications
Clear all

Forum 141

[Closed] Ekco TSC113 15" beasty.

44 Posts
11 Users
0 Reactions
4,188 Views
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

Hi all

As posted earlier, I bought one of these off ebay a little while ago. I have done very little work to it so far apart from restoring the mains derived EHT generator, a voltage doubler giving about 12kV 8)) 8)) . There are pictures in the thread "What's this then" (I can't find out how to insert a link to the thread).

I eventually obtained the full Ekco service data from a friend and from these, got the instructions for getting the CRT out. It is a CRM151 which can only be described as a bomb waiting to implode (if bombs have ever imploded) so I didn't want to do it blind as it seemed to require the opening of the lid through 180 degrees (which indeed it did).
After much consternation, the tube is now out of the set and I thought you would like to see a picture:

To give some idea of the size, the valve next to it is a PZ30 HT rectifier from the same set. I am amazed at the number of bubbles in the glass bowl - some quite large and some even on the face plate. I will, of course, be extremely careful with this CRT and the set with its double whammy of the 12kV brute force EHT and the "bomb with bubbles!

The cabinet which is, unfortunately, rather wormy (or "has mites" as the vendor described it), is outside on our covered patio to benefit from the frost as well as a good dousing in killer.
Hopefully, I will be able to get down to this set sometime in March.
I will be undergoing an Arthroscopy procedure to sort out my left knee next week so will be keeping out of my workshop for a week or so but I will be photoshoping some service data that I have borrowed during that time.

Forum Memorial

 
Posted : 27/01/2013 3:25 pm
Till Eulenspiegel
(@till)
Posts: 4947
Famed Member Registered
 

Hi Brian,
I've tried to install the Dropbox into the laptop but I'm sure it will be OK on the shop computer.
The CRM151 has a very narrow deflection angle, it's evidently the same as the CRM121 which is 57 degrees. In fact I wonder if it is even narrower when one looks at the length of the tube.
Unlike the smaller Mazda tubes the CRM151 requires at least 10KV. Although based on the Ekco TS88 which has flyback EHT, the TSC113 has mains derived EHT in a doubler circuit. Two Mazda U22 rectifiers and two 0.1 microfarad visconol capacitors are employed to produce the 10KV.
So along with the scary CRT there's a scary EHT system to contend with.
Before starting any work on this set I would replace those Visconols. I'm sure there is an Ebay seller offering suitable capacitors.
On my set which actually is a TSC1113, the Birmingham version, the CRT lift and lowering mech has got stuck. It's kinda scary thing considering that CRT. I'll download the dismantling data you have kindly sent me.
I look forward to your resto job on the set and I will track each stage of the work done on my set.
But wait until you are fully recovered after your operation. The set is almost in the heavy engineering league.

Till Eulenspiegel.

 
Posted : 27/01/2013 7:23 pm
Anonymous
(@anonymous)
Posts: 16868
Group Deactivated Account
 

second one down?
http://www.electrojumble.org.uk/passives_012.htm
rob t

 
Posted : 27/01/2013 8:27 pm
Till Eulenspiegel
(@till)
Posts: 4947
Famed Member Registered
 

Hi Rob
Thanks for the link. As well as the Visconols there are some useful items there.

Till Eulenspiegel.

 
Posted : 27/01/2013 8:35 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

Thanks for your best wishes, Till. As to the Visconols, they are already done with ASC capacitors in them. I wouldn't ever leave Visconols in situ without stuffing them.
I have several huge Visconols which were bodged into my Cossor 54. Of course, they had to go so if anyone wants them, they're up for grabs!

Forum Memorial

 
Posted : 27/01/2013 10:22 pm
sideband
(@sideband)
Posts: 4225
Famed Member Moderator
 

To give some idea of the size, the valve next to it is a PZ30 HT rectifier from the same set.

Strange but when I was servicing these and similar sets, the tubes didn't seem so big and frightening, probably because we saw them nearly every day and just took them in our stride. One that did worry me was the huge 21" fitted to the Ferguson 308T. The CRM141 from my Ekco T283 (which is similar to the CRM151) didn't bother me at all though.

I think I would be very careful and cautious of one of these beasties now.

Rich

 
Posted : 27/01/2013 10:48 pm
TNC
 TNC
(@tnc)
Posts: 148
Estimable Member Registered
 

Memories of my Ekco TC165 restoration (2009) remind me that I sourced the 10kv caps. for its EHT doubler from the German supplier Jan Philipp Wuesten - excellent qulity/service.

(& for those with long memories, the picure kink is still there!!)

Trevor :smile:

 
Posted : 27/01/2013 11:05 pm
sideband
(@sideband)
Posts: 4225
Famed Member Moderator
 

Ask-Jan-First. A very good supplier and has a pretty good range of bits.

This useful link by Brian has now been moved to Suppliers and Resources here

Rich

 
Posted : 27/01/2013 11:37 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

A bit more progress on this set. The main chassis has been de-rusted and much of the rubber wiring replaced as well as all the paper and electrolytic caps.
On applying mains via a Variac, there were good signs of life with the timebases running at approximately the correct speeds. There was initially no vision or sound although voltages seemed about right - I then discovered (or remembered :=D ) that the set is a TSC1113, the Birmingham version. With the Aurora switched to CH4, RF on the vision detector appeared but nothing on the other side - there was a very poor receptacle in the 6D2 (EB91) valvebase - no heater. I replaced it by using a receptacle from an identical scrap base. A good tip is never to throw a defective valvebase away if the contacts are removable as it is much easier to ha contact rather than the whole base. Sound is a bit low but I'll sort that later.
This set has a 12kV brute force EHT generator, not a thing to mess with, so I haven't fitted it for the preliminary tests but have relied on my bench EHT generator (3kV) to get first light. Also, the 15" CRT is a bit risky to mess about with so I am using its smaller cousin, a 9" CRT. The scan coils and focus assembly are just parked on the tube neck with the EHT generator hooked onto the final anode. I was rewarded by a very defocused and very vertically crushed test card. The crushing was sorted by changing the SP61 frame output but the focus problem is not important as the CRT, EHT and CRT are "foreign" and the focus assembly may not match the 9" tube.
There are a few more things to tidy up but I'm getting nearer the time when I must power up the EHT generator :omg: :omg: .

Forum Memorial

 
Posted : 18/03/2013 9:35 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

Not a lot of progress after my last post except that, in order to get the 15" picture bomb on the bench, I decided that I needed to make it as safe as possible, hence the stand. The second picture shows how much room the bomb will take up on the bench!

Forum Memorial

 
Posted : 07/04/2013 10:46 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

A bit more progress - but in the 'elf 'n safety direction :=D . This set, as well as the bomb shown in the earlier post, it has 12kV of mains EHT so H&S is really quite important with this one 8)) . The pictures show the permanent precautions I have built into the set. The guards are made from 3mm acrylic, bent with a heat gun where necessary and bolted onto the chassis.
Tomorrow, I will mount the CRT properly into the cradle and get ready to power up. Hopefully, the EHT transformer is OK! Talking about the EHT transformer, when I first got the set, two of the brass wire connections were broken - I guess the brass has gone brittle - but when I started serious work, 4 out of the 6 had snapped :~ . I could get to the remaining bits ao I decided to cut the remaining ones so that they didn't snap later and perhaps too low to make a connection with out too much mining! Now at least, all the connections look similar.
Roll on tomorrow :D

Forum Memorial

 
Posted : 11/04/2013 10:04 pm
Till Eulenspiegel
(@till)
Posts: 4947
Famed Member Registered
 

Hi Brian,
I've still not summoned up the courage to make a start on my TSC1113.
We all make jokes about this H & S business but you are certainly right to add those safety procautions to your set. 12KV derived from the mains is no joke. At least the regulation will be good and better than most early line flyback EHT systems.

Till Eulenspiegel.

 
Posted : 12/04/2013 6:27 pm
crustytv
(@crustytv)
Posts: 11932
Vrat Founder Admin
 

This is one of those rare occasions when I'm inspired to do a Hunty cartoon.

CrustyTV Television Shop: Take a virtual tour
Crusty's TV/VCR Collection: View my collection
Crustys Youtube Channel: My stuff
Crusty's 70s Lounge: Take a peek

 
Posted : 12/04/2013 7:00 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

::::) ::::) ::::)
Be asured, Chris, it wouldn't be just a little "parp!

It's now on the bench with the CRT in its cradle but no sign of life using the bench EHT generator (I thought it better to get first light on the CRT without enabling Battersea)!

Forum Memorial

 
Posted : 13/04/2013 2:06 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

Absolute gloom :cry: :cry:. The CRM151 is totally knackered! Zero emission on the Radar 202 tube tester.
I decided to try Alistair's gentle method using my bench PSU and a 33k resistor with the heater powered from the tube tester as this can give 10%, 25% and 33% boost.
On 10% boost and 300VDC there was no deflection on the AVO across the 33k. at 33% boost, I got about 2.5V. With nothing to loose, I left it on 33% all afternoon and when I went to have a look just now, the Avo was reading 45V so a considerable improvement. I have now left the heater on 0% boost and will go back later this evening to turn the HT on again! This will be a real test of the system as there was absolutely no life lect in my picture bomb!
p.s. Any one got a spare one?

Forum Memorial

 
Posted : 14/04/2013 7:58 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

A bit of further information: after Alistair's "treatment", the CRT showed towards the top end of the red on the tester whereas, as said earlier, there was absolutely no movement of the needle whatsoever so much improved!
Now came the time to power up the EHT unit with the CRM151 in circuit. I disconnected the EHT mains transformer primary from the chassis and fed it separately from a 1A variac so that I could wind it up slowly - sorry John! Result - absolutely nothing on the screen although I got exactly 12kV! I connected the bench EHT supply and got an image of sorts so what's going on? The EHT lead was O/C - it had broken at the CRT connector end. That repaired, I tried the proper EHT and was rewarded by a picture albeit a bit dim :=D .
I must admit, I've seen worse tubes so I reckon if I boost it say 15-25% I should get a reasonable picture - I'm sure I have a boost transformer somewhere. There is now just a low sound problem which comes and goes with instability so I will examine the RF strip.
The cabinet should be ready in a couple of weeks so I'll be able to get it together, take some pictures for the thread and put it in my display shed!
Next, it's the GEC 8161!

Forum Memorial

 
Posted : 16/04/2013 5:44 pm
mark pirate
(@mark-pirate)
Posts: 497
Honorable Member Registered
 

Glad you managed to coax some life out of the Mazda airbag, I had the same problem with my CRM92 in my Baird set, I tried the 'clean & balance' function on my CRT tester, this did improve it, but I am not willing to risk using the rejuvenate function unless I can source another tube, increasing the heater voltage did bring up a brighter picture, but it is still watchable on 2v.

I have yet to tackle a mains EHT set, but I will certainly copy your example of fitting some proper protection.

 
Posted : 16/04/2013 6:54 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

I'm surprised that 12kV EHT didn't arc across the break in the cable and make its presence obvious.

The EHT cable is made from a coax inner type cable inside a larger PVC sleeve (with plenty of room). The shroud for the anode connector is pushed tightly inside the larger sleeve so I couldn't see that the inner had come adrift and moved back about 1/2", too far for 12kV!

Forum Memorial

 
Posted : 16/04/2013 7:04 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

I have yet to tackle a mains EHT set, but I will certainly copy your example of fitting some proper protection.

Hi Mark
That's the first thing I do after the restoration is complete and before I put mains on the EHT transformer. I don't mind mains EHT sets but I do treat them with the utmost respect (and I'm still here to prove it)!
This is the first time I have used a small Variac to power transformer but I will use it in future as it does give absolute control. If the EHT rectifier heater winding is on the same transformer as the high voltage winding, a solid state rectifier could be used during the initial testing.

Forum Memorial

 
Posted : 16/04/2013 7:11 pm
Brian Cuff
(@briancuff)
Posts: 2063
Member Rest in Peace
Topic starter
 

I have at last, got the TSC1113 going reasonably well having re-capped it and replaced about 8 resistors. I had a lot of trouble with the sound strip (it's a TRF) but traced the fault to a tiny solder bridge (mea culpa). Then, the set seemed to die slowly and come back up, also slowly. After lots of head scratching and meter bashing (I don't like digital readouts) I found a very old dry joint in the connection of one end of the 6.3V heater winding to deck! It looked perfectly good but eventually, having narrowed the problem area down, I gave it a hard tweak - after all, it looked to be 16swg so not delicate. I noticed that the wire moved but the solder tag didn't. a quick application of the iron and all was well.
The tube, even after Alistair's treatment, was as dull as ditch-water but with 25% boost (by measuring heater current) the picture was good and bright and totally satisfactory so I will fit a 2V 25% boost transformer and post a couple of wants in the appropriate section.
So now I can get the cabinet together after its trip to the polisher and finnally get my second bench back. The main bench is full up with the GEC BT8161 chassis and that won't be going anywhere anytime soon.
I'll post some pictures as soon as it has been completed!

Forum Memorial

 
Posted : 04/10/2013 11:57 pm
Page 1 / 3
Share: