CS2030 - does anyone have a diagram please?
Been working my way through tracing a hum bar on the supply, got that sorted, then set about sorting the frame and was just thinking of setting up the convergence, when I'm met with no raster and a PL509 that's cherry red 
Tube is a peach though .... Hope I don't need to invoke my spare LOPTx already !
have you checked the boost cap on the time base board the one by the with control
rob t
Is that the 0.022 1KV ?
I'll need to sub it out, but don't have anything like it. I'll have to eBay myself a replacement.
I wonder if that was the issue with my HT falling ..... Drawing more current, until it left the pl switched on. Possible.
I had started to lose height and width before it jacked in, although it was a bit more of a slow process than I would have expected.
Hi Doz,
I think the Decca Bradford manual is in the technical library and already on the forum. 
Is that the 0.022 1KV ?
I'll need to sub it out, but don't have anything like it. I'll have to eBay myself a replacement.
I wonder if that was the issue with my HT falling ..... Drawing more current, until it left the pl switched on. Possible.
I had started to lose height and width before it jacked in, although it was a bit more of a slow process than I would have expected.
that sounds like the one if its white or blue and white its suspect they tend to go short so can be checked on an avo.
first check would be to measure resistance between top cap of boost or line output valves to chassis.
another easy check is to disconect the tripler from the lopty.
before condeming the tx check the screen grid volts on the pl509 and if you have a scope the line drive on it's grid.
rob t
Is that the 0.022 1KV ?
I'll need to sub it out, but don't have anything like it. I'll have to eBay myself a replacement.
I wonder if that was the issue with my HT falling ..... Drawing more current, until it left the pl switched on. Possible.
I had started to lose height and width before it jacked in, although it was a bit more of a slow process than I would have expected.
that sounds like the one if its white or blue and white its suspect they tend to go short so can be checked on an avo.
first check would be to measure resistance between top cap of boost or line output valves to chassis.
another easy check is to disconect the tripler from the lopty.
before condeming the tx check the screen grid volts on the pl509 and if you have a scope the line drive on it's grid.
rob t
Yep .22 and leaking like a sieve. Ordered a new one. It's red and silver, and now has a suspicious bulge at one end!
New boost cap fitted, line output stage now running. Neither the loptx or the PL509 seem to have suffered any long term ill effects
Picture is fantastic, the tube is really punchy, bright and pin sharp. Convergence is a way out, so I put my test pattern disc into the DVD and hit play.
No picture, low and distorted sound. Modulator checked - innocent
Right, back to the tuner end. Voltages OK... IF output OK.
Move through the IF, 31 volts on L28, 1st IF OK, 2nd IF OK ....and almost nothing from the output of the 3rd IF transistor TR6, a BF197.
Switch off and a static test with the trusty fluke shows it's still got two junctions. Switch back on and rewarded with a superb picture once again 
... which was sadly short lived. A squirt of freezer (actually air duster upside down!) on the offending transistor restored operation briefly, although this could only be repeated a few times, as the fault is now present permanently 
I've not got any BF197s, so I'll pop into PJ Hill tonight and pick a few up for stock
lockfit transistors are number one suspects in 70's decoder and IF strips.
rob t .
Popped up to PJ Hill's at lunchtime and got a few of BC148, BF196 and 197 for stock. Also 100ohm convergence pots (imperial or metric, sir? !)... oh yeah, and a cup of coffee (thanks Pete!)
Sadly I won't have time to play tonight, as I need to go and do a few little jobs for the wife (she owns a nightclub in Cheltenham, and the Irish are coming for the festival, so there's a few maintenance tasks to perform in time for next week). She has promised to ply me with a curry though 
Ah yes! The "Lockfit" cased transistors from the 70's seem to be giving a lot of probems now. Had several go open circuit in various ways in the decoder in my Pye CT71 and the amount that Mikey Bennet's had to change in his sets are unbelievable!
Any ideas to the mode of failure? Are NOS going to be any good? or should I be looking at modern equivalents?
Is it the dreaded AF117 all over again?
Not too sure but the the main thoughts are that the encapsulation of these types is not fully moisture proof. That said, if the new ols stok ones have been favourably stored, they may well be ok. Certainly the ones BF195s that I bought from Cricklewood Electronics are fine...so far!
I would have thought bond wire fracture. These kind of transistors probably have a silicon oxide top layer (essentially glass) so moisture ingress not a huge issue. There is no heavily tinned can lid to be a source of whiskers. The lead frame design is poor compared to TO-92. The idea was for simple auto-insertion and the parts not falling out.
More advanced and flexible auto-insertion equipment using parts on bandoleers quickly made the package obsolete. The T092 was also much cheaper and more reliable. I think a BFx5x / BCx5x is the same TO92 part as the same number BCx4x / BFx4x Lockfit or metal can BCx0x / BFx0x part.
The same series is also in SO SMD parts. In some cases you can actually solder the SMD equivalent direct to PCB pads.
Spent a little more time on this today. Replaced TR6, which has "sort of" restored the IF. A strong signal from the modulator will now show up, but there's no snow as there was before. I now suspect TR10 as well 
Whilst sorting out the power supply I have a couple of questions.
My power supply appears to have two transformers and a choke, and yet the diagram I have only shows one.
and also, this wire appears to have been cut from the lower transformer. It connects to the mains smoothing block's ground... why?
I'm currently short of another BF197 and left with a rolling frame that locks occasionally. I do wonder whether this is being caused by less than enough signal from the IF to the decoder. When the picture locks it does lack the punch it previously had, and has a certain amount of grain to it.
one of them is the frame output tx.
rob t
This seems to be typical of a tv that i have for a while and then decide to sell. and while i have the set it works fine for me but the minute i sell it to someone else it has a hissy fit and goes wrong . if you want to come back this way anytime then ive got a manual you can have along with the mains choke and the frame output transformer etc. cheers,Neil.
one of them is the frame output tx.
rob t
Ah yes, of course! Doh
This seems to be typical of a tv that i have for a while and then decide to sell. and while i have the set it works fine for me but the minute i sell it to someone else it has a hissy fit and goes wrong
It's all part of the fun, Neil. It's what this hobby's all about!
I've been and got a handful of BF197's this morning, so I'll have another go. I won't be beaten!
At ideas about the mystery cut wire???
Sorry i've no idea about the chopped wire as i never had the chassis out of the set. although you could ask Lee or Tas as they both had the set at one point cheers,Neil.
