exxos's Atari, Amiga & retro forum

It's a pain that the board needs +12V, +5V, -5V and -12V too! I don't know what the minimum required to boot is.

stephen_usher wrote: 14 Dec 2021 18:32 It's a pain that the board needs +12V, +5V, -5V and -12V too! I don't know what the minimum required to boot is.

Me either, I forgot it's been too long!!

With respect to the HDD not powering up. That sounds like there's a short on the +12V line.

stephen_usher wrote: 14 Dec 2021 18:45 With respect to the HDD not powering up. That sounds like there's a short on the +12V line.

My thoughts too.

Pages 21-23 of the Dead Mac Scrolls are showing some good tests that I need to work through as they pretty accurately describe the symptoms I'm getting. Every page says analogue board, so this is something that has failed since I started to look at it.

Does a atx extension cable plug in most of the connector is the same you may need to move some of the wires

Tom

@rubber_jonnie

On the analog board have you reflow all the connectors and wires goings to yoke tube neck and flyback pins look for cracks around those as well


Tom

Tomswork wrote: 14 Dec 2021 18:58 @rubber_jonnie

On the analog board have you reflow all the connectors and wires goings to yoke tube neck and flyback pins look for cracks around those as well


Tom

I think I did, but I'm going to check again because it has been moved into and back out of storage since I last looked and my memory is hazy.

I'll have to see what I can do re extending the cable, I simply don't have a spare ATX plug I don't think. It is 'kind' of workable ATM but I will do all the suggested analog (I just realised I was calling it analogue!!) board checks and check all of the neck board wiring too.

Looking at the 3rd party schematics for the Classic, it doesn't look like the -12V and -5V are used on the board and the +12V is only for the floppy connector and serial ports, so you should be able to power the board from +5V only externally and then take the v-sync, h-sync and video from pins 4, 5 and 6 of the power connector. (+5V on pins 2 & 3, Ground on pins 10, 11, 12, 13 and 14)

I do dislike the way that the 3rd party schematics are done. The +5V, +12V, -12V and -5V symbols are extremely confusing and able to be misinterpreted.

Tomswork wrote: 14 Dec 2021 18:55 Does a atx extension cable plug in most of the connector is the same you may need to move some of the wirea

Tom

Beware that the Classic connector and SE/30 aren't compatible and there are a bunch of functions, such as sound, which go through the connector which the SE/30 doens't have. It looks like there's no -5V input on the classic, it's generated from the -12V line.

Looking at this, personally I'd solder wires to the ground and +5V points on the underside of the board and power it from a bench power supply initially. You can then get the two syncs and video and try to see if it's outputting anything.