1969 Bush CTV187CS - A823 Chassis

The main cause for the ic,s on the decoder to fail is if the two earthing screws on the psu are not tight. The thermistor (VA1104 if i remember) should be replaced if it sparks on switch on. A company produced a replacment psu for this chassis which used a soft start circuit which did away with the thermistor. These psu,s were very poor design and gave poor ht regulation, ie- picture bounce on bright scenes.

I forgot about the loose screws .
on 3 or 4 ex rental sets we bought, an engineer (sic) had decided to overcome the thermistor problem by simply twisting the wires together .
Rob T

I also forgot to mention the earthing screws on the decoder pcb must be tight. Rob, i have also seen the thermistor shorted out by twisting the two legs todether The BT106 objects to this *mod*, Malc.

Rob and Malc have been offering up good tips for the Bush CTV187S but in the PYE CT203 thread.

So as to not loose them and as I had not yet started a thread for the Bush, I decided to start a separate thread now and move their valuable tips over to here.

Another quick warning if the line stage does not start up those big electrolytes can hold a charge for a long time guess how I found out.
Rob T

There should be bleed resistors across both smoothers. 47k or 470k rings a bell. I once got a belt from one off those smoothers and caught my hand on the crt base pcb, followed by a long hiss from the crt. Make sure the 56-68 ohm wirewound dropper behind the smoothers has not been bodged.

That's exactly what happened to me fortunately it was not a customers set but yet another ex rental.
Rob T

Chris,

somewhere in one of my junk boxes I have a few NOS VA1104s. If you need one drop me a PM. FOC + post as usual.

Al

Hi Al,

Nice to know there is so much help and support out there in VRATland

Chris

I should have NOS decoder ic.s and VA1104 thermistors in stock, Malc.

A rainy Saturday here so bored I decided to switch on the Bush to see what the picture was like and I got a shock ( Not electrical)

Prior to receiving the set it has only had the frame output transistors replaced along with the midpoint balance pre-set, linearity preset, line drive capacitor and resistor.

I fed the set a test card and was surprised at the quality, linearity, purity and convergence all look good.

Now I've heard that these never gave as good a picture as some of its contemporaries, I have to say it's great. Nice and bright, lots of control on brightness/contrast and colour. The verticals on the test card however are occasionally wavy and the picture bounces every now and then so some work is needed, but a pretty good basis to work from. First will be to get the power supply up to scratch then take it from there.

When I turned this set on the sound was awful like the PYE & Hitachi, I thought hang on this cannot be happening to so many sets, so I dug out my 70's Mitsubuishi a known good worker, that was the same. I have now discovered my RF modulator has developed an audio fault. It was a cheap jobby from e-bay, so I've ordered a better model now.

Anyway looks like the Bush will be a fairly straight service to eliminate the issues it has. Another bonus is the wife reckons it will look good and more in keeping with the house as our main TV ,instead of the flat panel

Hi chris.
Does this set have a single or two chip decoder?
In my opinion the single chip gave an excellent picture the two chip being a retrograde step.
Rob T

Hi Chris,

You lucky little blighter ! that Bush doesn't look bad at all
Mind you after the Pye CT203/1 you deserve a break

Marc.

Trouble is the pye will now have to have its sound readjusted,
Rob T

Yep already thought that, still at least I know its a minor twiddle of L19. As for the Bush decoder its the single version. I've done nothing other than plug it in then spend the rest of the afternoon eliminating the cause of the audio.

Another bonus is the wife reckons it will look good and more in keeping with the house as our main TV ,instead of the flat panel

It's funny you should mention that because when I was 15-16 I desperately wanted one of these sets in order to impress my girlfriend. Up until now I've had no way of knowing whether it might have done or not.

It's looking good already Chris . it might mean that i'll have to get my CTV197C going , but please no one hold your breath .

Cheers,Neil.

Is your modulator the type with 2 push buttons underneath to set the channel number?

If so, press and hold both buttons for 5 secs , and check it still says 6 on the display and not 55. I completely realigned my G8 with it accidentally set for 5.5MHZ sound

Watch out for a pitfall that anyone who has worked on this chassis will have done at least once.

It's very easy due its position to forget to plug in the degauss coils after refitting the chassis to the set, doing so will put all the current that should go via the coils through a 680ohm resistor on the power supply producing clouds of smoke.