My Issue 2 continuing problems and Issue 6s fixed

[redgatemodels]

Had a play this afternoon, first completed the power service mod on the series 2, also attacked it with switch cleaner and a toothbrush.

That tatty power socket will have to go, but all in all it’s shaping up nicely now. Solid, dependable, a good basis for future use.

Next onto the series 6, I disconnected the capacitor comp mod and fitted the "better" pcb based comp mod https://www.ebay.co.uk/itm/325671141251

It seemed to be dimmer than the simple cap so I put it back for now. Let's see if the transistor mod is any better

[redgatemodels]

Rubber key membrane turned up on Saturday, but as I was playing trains all weekend at the Elizabethan Model Railway Exhibition, no progress made on the classic case.

Hope to fit it in this week sometime. Transistors have also arrived to have a go at that version of the comp mod, although the 6s pcb failed when I was playing a game on it (yes I know, I should have waited until I'd recapped it).

[redgatemodels]

OK, so

Fitted the new membrane to the rubber key case and no joy with the series 2 pcb. After lots of testing, switch cleaning, finding a broken track on the 5 way connector, trying the plus case keyboard, it struck me

I've fitted the replacement keyboard connectors the wrong way round

I'll have the desoldering pump out someday and try not to break any more tracks and turn them round so that the spring contacts actually contact the conducting side of the membrane......

[redgatemodels]

Well, 1 step forward, 2 steps back. Keyboard now works but instabilities have returned. Certainly does not like the case closing up - crashes very quickly and the colour problem is randomly reoccurring. It never crashes with the diagnostic ROM plugged in and memory tests go through fine etc.

I'm tempted to remove all the socketed chips and give the whole board a damn good scrub, dunno.

Oh and the ear socket does not work. looks like that needs replacing too, probably oxidised beyond bringing back by years in the loft. If I press down on the contact nearest the tip of the jack then we get a signal coming through.

Would the ULA from the 6s work in the S2, assuming it's not fried?

This is all the Series 2 pcb, yet to recap the s6 to see if I've really killed that too

[1024MAK]

Is this a diagnostic ROM that you are plugging in, in place of the BASIC ROM?

The Ear (and Mic) sockets making poor contact is not unusual. You can normally bend the contact slightly using a screwdriver, that often improves matters.

The ULAs are backwards compatible, that is, a later ULA version can be used in an earlier issue board. But an earlier ULA may not work in a later issue board. Hence you will find boards that have been repaired that contain a much younger ULA than typical.

Mark

[redgatemodels]

Is this a diagnostic ROM that you are plugging in, in place of the BASIC ROM?

Mark

I think so, it boots straight into the room etc

[1024MAK]

I mean, are you putting a memory chip in place of the BASIC ROM chip?

As opposed to plugging in an expansion board in the edge-connected.

Mark

[redgatemodels]

Oh sorry, no expansion card plugged in

[redgatemodels]

Progress today on the 6s PCB. After recapping it all the interference has gone away, so I've done the transistor comp mod and buttoned it up in the plus case for now.

I will probably swap the ULA from the 6s into the s2 to see if that improves matters, after I have given the pcb a damn good clean - all socketed chips removed and switch cleaner used etc.

[redgatemodels]

I also want to see how it performs without the upper RAM