BBC Model B No2. Will it live again!

[rubber_jonnie]

What happens if you change to a non-teletext mode, e.g. Mode 1?

If the Teletext chip has blown then you would get no display in Mode 7 (default) but would in the other modes.

Good tip, I will try.

[PhilC]

Nice, I knew I could trust in you for some Burning Rifa action @rubber_jonnie :lol:

[rubber_jonnie]

Nice, I knew I could trust in you for some Burning Rifa action @rubber_jonnie :lol:

Always!

:girldance: :girldance: :girldance:

[rubber_jonnie]

What happens if you change to a non-teletext mode, e.g. Mode 1?

If the Teletext chip has blown then you would get no display in Mode 7 (default) but would in the other modes.

Interesting, the Teletext chip is from Mullard, a name that rings a bell as my uncle used to be a TV repairman.

[stephen_usher]

Indeed, Mullard designed the Teletext system in the first place in the early 70s. I think the business was bought out by Thorn at one point.

[rubber_jonnie]

Indeed, Mullard designed the Teletext system in the first place in the early 70s. I think the business was bought out by Thorn at one point.

Ahh, Thorn, there's another blast from the past!!

Interestingly, one of the places I go to get older components, Cricklewood Electronics, has them in stock, which is good. eBay also has them branded as Philips.

[stephen_usher]

Oh, it might have been Philips who bought them then. I know that they got gobbled up.

[rubber_jonnie]

Oh, it might have been Philips who bought them then. I know that they got gobbled up.

Bought one to have as a spare, in the middle of rebuilding the keyboard ATM on the replacement PCB.

[rubber_jonnie]

Ok, status as of now is that the keyboard is almost rebuilt, bar 4 Fn keys that I've left off as I tested all the switches prior to reassembly for continuity and they all failed.

I've given them a squirt with contact cleaner, but no joy, so I'll just have to get some replacements.

I get a BooBip on boot, and the caps & shift lock work just fine as does the cassette LED.

The new problem is that I have no video output. Blind typed commands are clearly working but attempting to change screen mode makes no difference so potentially rules out a problem with the SA5050 Teletext chip, though I have ordered a replacement anyway.

I know the composite works fine on No3, and I can see a 15Khz signal on the composite output of No2, but I suspect it's not something the TV understands. I need to compare the signals so I can try and figure out whats wrong, so good vs bad.

I'll also see if I can get anything on the UHF modulator, but not that hopeful with the TV we have here.

Faults found so far? Dead CPU and bad keyboard. Let's see what's next.

[BennehBoy]

Congrats & cheers! Whisky o'clock here, been diagnosing an A600 PLCC RGBtoHDMI adapter for the last 2 hours. It's giving everything a blue tinge, including the standard RGB out - anyhow looks like the flip flop might be duff as I'm getting a partial short on the red high bit. It worked when it arrived, replugged it and it's gone bad, bah.

So in short, I have some sympathy with you at the moment.

Have you tested those roms I sent in no3? No rush, just my OCD worrying that I may not have burnt them correctly :D