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RGD CR20

 
The_Teleman
(@the_teleman)
Active V-Ratter Registered

this set was and still is a challenge ! it's badged as RGD & is fitted with the ITT CVC5 chassis & a 20 inch CRT

on first inspection , OH MY ! Who has had a go at this ? So many components fitted on the print side of the pcb I didn't know where to start

I wish I had taken some photos before I started but in my eagerness to have a go , well you know what it's like you start & do a little bit then before you know it !

On powering up the set I had sound but no picture , dropper resistors getting rather hot rather quickly so some loading of the HT lines was my first thought .

disconnect  the tripler first & try again , this time I had no overheating & a nice healthy spark at the PL509 anode cap , nice easy one ? Wrong ! Yes the tripler was loading the lopt but all these components on the print side of the pcb was getting to me

so I decided to fit all the components back in the correct places , now I know why they are on the print side ! This was a challenge & one I quit enjoyed really I did also have the presence of mind to check them before I refitted them .

so the set now looked better & a new tripler fitted & replacement of the 4.7 meg focus resistors while I'm at it

this time I had a raster poor but it's a start , the focus was still way out & it looked like the red was missing . The focus was sorted by replacing the 2.2meg on the CRT base , the no red ? Mmm that looks like the CRT to me , so out with the CRT tester green & blue read over 80 % on my leader tester but the poor red was nowhere to be seen ,not a peep , so I left it on with a slightly higher heater voltage to see if it would come to life NOT a chance only managed a slight meter movement . It's time for drastic action reactivation! Well that failed too only managed to get the meter to read poor so after all that I'm on the lookout for a 20 inch delta CRT image.jpeg

if anyone can help please get in touch

chris

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Topic starter Posted : 03/06/2017 1:47 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

That's such a shame Chris as it looks a pretty decent cabinet. Those 20" CRTs could be pretty variable even back in the day, some went flat very quickly especially the Japanese manufactured ones which also didn't respond well to reactivation. A relative of mine had a GEC 2110 chassis 20" where the emission fell away not long after the years warranty ended. I'm fairly sure that it was a Toshiba CRT, what's in yours?

John.

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Posted : 04/06/2017 11:21 pm
The_Teleman
(@the_teleman)
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Hi John , this set is fitted with a Toshiba CRT but I feel sure it has been changed at some time in its life because as an ITT dealer in the distant past I'm sure these set should have Hitachi crts in them .

a very good friend has come up with a CRT so I'm hopeful this will be sorted soon

cheers

chris

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Topic starter Posted : 08/06/2017 1:33 pm
Focus Diode
(@focus)
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Thi suspiciously sounds like the set I once had. Yes, one or two components were mounted on the print side of the line output panel but not very many. I attempted to cure an intermittent line collapse problem. Nothing, not even replacing the LOPT cured this.

Warm up could be difficult with the raster collapsing a few times before settling down. The set would then run for hours with no problems. If a bright scene appeared the raster would collapse momentary. In the collapsed state the boost voltage also collapsed. The PL509 would also run cool

The only other problem is the width controls didn't work either but I wasn't too worried as the EHT was bang on 25kV.

I'd fitted a first class Hitachi CRT from a scrap GEC 2110 model. Surprisingly the original low emission one was the same type.

A house move resulted in me parting with the set. I understand the Hitachi CRT I fitted was replaced by a Toshiba type.

If it was my set I would be most interested to hear if the line collapse fault has been cured. With a poor CRT the fault might not show up.

Incidentally the 400mA feed fuse to the line output stage should have blown in the event of a faulty tripler. Check to ensure the fuse fitted is not over rated.

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Posted : 28/06/2017 3:37 am
The_Teleman
(@the_teleman)
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Hi Focusdiode, This definitely sounds like your set , one I sorted the width resistors out & refitted the components back in the original positions the set functions well with no line collapse problem , the set still works well now only with a poor CRT  the red has all but died

the only thing that may of caused the fault is with excessive beam current & combined with the width problem may shut the line down giving the fault you describe .

I have known these sets do this sort of thing in the past as an ex ITT dealer we used to get all sorts of strange faults .I/f faults that sounded as if you had tuned into a foreign radio station for one .line osc fault when it would simply refuse to start for another .

one that had me for a while was no sound everything around the sound output was as it should be but if you touched the grid to the triode section the sound would come on & go off or fade off when you removed your probe

the fault was eventually traced to a 10 meg resistor in the line section that acts as a mute till the line is running so it gives the appearance of the sound & picture coming on together .

Ofcorse this fault has been recorded many times since & no doubt some one will say it's one of the many common fault but back in the day it wasn't so common .

ill let you know when I get a good CRT for it how it goes

Chris

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Topic starter Posted : 02/07/2017 6:55 pm
Focus Diode
(@focus)
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Hi Chris,

I had the IF fault on the set, cured on replacing the three transistors on the IF subpanel. The sound and line osc/frame stage has been completely trouble free which might be due to carrying out preventative maintenance on the bottom panel.

The set was put into full domestic service giving excellent results. The LT bridge rectifier eventually failed giving a hum bar on the picture. Hardly exceptional nor expensive to put right.

The line collapse problem developed suddenly which lead me to believe the cause was component related rather than through misadjustment Everything was fine until the fault suddenly developed. Perhaps significantly the colour failed at the same time. I cheated with this by o/c the CK diode which restored full and reliable colour. Not necessary nowadays with everything broadcast as colour.

I tried new components and checked the heam limiter. Hopefully the fault has been cured but it might not show up on a poorly CRT. Does sound beam current related as you say, but puzzling how the fault developed suddenly after working perfectly over a long period.

Sorry for any gobbledegook, this forum doesn't work well on my mobile for some reason. When I first replied to your post it printed "sad" at the top for some reason!

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Posted : 04/07/2017 2:51 pm