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So, I have a final update on this little guy, and it's all running just fine!! I sorted out the bong/flup issue, which was QP2, an IRF-BC40 MOSFET, which after replacing left me with a fully working power supply that powered up everything just fine. I then hit another issue whereby with the...

I will, working on a list of caps and replacing what I can from stock in the meantime :)

Wow, I just realised how long it's been since I last posted about my Classic on here!! What with covid and moving house this year, I've not had much time to look at this. However, it now lives again!! So the logic board was dead, and I have been able to secure a replacement, which is great...

I did, and am getting about 8Mhz as expected. /HALT & /RESET lines are behaving as expected, so 5v when running, and 0v when reset is pressed.

Ok, so it's been a while since I looked at this machine and it occurred to me that it might be worth trying to bypass the AB because I don't have a lot of space available to put the whole machine out to work on. The line of reasoning goes like this: 1. I have a PSU that I can use to deliver...

Sadly no luck as yet, I will keep at it though.

So I have a socket fitted for the68K now (Checked for shorts and continuity BTW), and the CPU doesn't overheat like an air cooled car in death valley anymore! Voltages at the power connector seem fine and I have -5v where I expect it too. But right now I have nothing on screen at all, no bong...

I'll let you know once I get time to work on it! Maybe this weekend all being well.

@dochilli Thanks so much, your 'care package' arrived today, it shows how bad the Maxell bomb can be!! My board luckily didn't have that, but clearly there is other stuff wrong. I have the old CPU off my board and a socket to install in it's place, plus a spare CPU (One from an Atari STE, one...

See my reply to techknight, they were only missing for testing.

I'm not that dumb! They aren't missing, just not fitted in that picture as I was testing for shorts. It looked like C5 and C9 positive sides were connected to GND, however looking at the circuit in that section, that is correct. They are connected to a -5v regulator, so the negative side of the...

That is amazing thanks so much!!

That is amazing, thank you so much. I will PM my address over, and am waiting parts for the next repair anyway, and won't be able to look at it this weekend, so things are going slowly anyway. I just realised that by Maxel bomb you mean battery leakage!! Luckily I don't have that problem, but...

That would be incredibly kind, though I am in the UK so I'm not sure how we could work it? I would of course be happy to cover the postage, would you want anything for the board?

On a positive note, I've confirmed that the 27C400 is a match pin for pin for the TC534200 mask ROM indicated on the schematic, and I have 2 27C400 EPROMS and ad they write/red fine in my TL866 with adapter. 

Ok, so I've pulled the CPU and with power on, nothing else get's hot, so maybe CPU and ROM are dead. Checking the voltages on the power connector (Now re-soldered), I get what I expect, 5v, 12v and -12v. Wondering if the CPU and ROM had some sort of pact to die together!! I certainly can't read...

So I have a couple of 27C400's and they program fine with an image I located on the web for a Classic, and I also have a 27C400 ROM emulator which can hold multiple images, and no different. I measured the 5v and 12v rails at the floppy port and it was fine. I also removed and refitted the...

@dochilli funnily enough I have just done that and will try it out later :) I'm using a 27C400, which is 512K, so I presume that will be suitable? The image wrote no problems, though I don't know if it needs to be byteswapped or not, but the ROMs I have are erasable so not an issue if they...

Yes, afraid it isn't great due to the sync with the camera,but you can see the difference, especially when zoomed in. I'm really hoping it isn't the onboard RAM. I am also posting on the forum I moderate on, got some good suggestions just come in over...

Thanks for your reply! The problem I have is that some of the RAM (8chips) are soldered onto the logic board. I probably should have mentioned that I have tried with the RAM daughterboard removed and I don't get the checkerboard, just fine horizontal lines. I can rework the RAM if required, I...