Another dead 130XE

[jorevall]

I have a friend who likes to go to recycle stations here in Sweden.

And he is a really nice guy, he found a Veller VP 801 EC de-soldering system, that actually works..

 

So he gave it to me..

 

Anyway, I have this 130XE that I think de previous owner tried to hook up to a none Atari psu.

He could not get it to work, so he sent it to me, as spare parts..

 

So when I got this Veller station I decided to try it out on the broken 130XE, and remove some of the circuits I thought where broken..

So with this tool I remove the circuits pretty fast..

 

I had a hunch the Freddie was gone, also the memory chips, so I removed them..

I also decided to put all the other Atari circuits in sockets.. (Sally, GTIA, POKEY, ANTIC, PIA, OS, BASIC)

 

I have a 130XE that is running, but has some modifications, so I decided to remove Freddie from it..

So with a working Freddie and a new set of working 64k1 DRAM's I manage to get a rostbrown picture.

I verified that I had good voltage, and all the clocks where ticking, also checked that the system was not halted or in reset state.

 

I replace the RAM for another set just to be safe..

 

Still same rostbrown display..

 

I had a chat conversation with an old friend and we talked about the different circuits, and we both felt that it might be an issue with one of the address decoders..

 

Due to the rostbrown display, it did not feel like the LS138 that handles the chip select for GTIA, PIA and Pokey, it felt more like there might be an issue with the C061618.

So I decided to remove it, and try a healthy one, Huston, we have lift-off..

 

The 130XE starts..

 

So basically, in this machine that presumably had been hooked up with a PSU with wrong polarization, the RAM, MMU and Freddie went to heaven..

 

I can’t not swear that it will act the same on other XL/XE who have been hooked up with a wrong PSU, but at least it can give a hint on where to start looking..

 

I have taken some pictures of the board in different stages, I will post them tomorrow if somebody would like to have a look..

 

I found the Bob Wooley MMU PAL source file, I will try that one, and for Freddie, I hope I can find one at B & C or similar places.

 

Keep on Atari preservation..

 

Regards,

Freddie

[Rybags]

Maybe it was hooked to a C-64 PSU.

 

It has +5 VDC and 12V AC, which in all likelyhood would kill an A8.

[1050]

It's a well known symptom for the RAM to "sacrifice" itself in the event of an over-voltage event coming from the power supply, but the MMU going bad that is news to me, thanks for the heads up. Although not much stock can be placed in the color of the "dead" screen, rust brown is a common one.

 

The very first thing one should always do is to check the power supply voltage to make sure it is exactly 5 volts.

 

Best Electronics has always been the place to go for Atari chips, BTW. Brad's $10 catalog is worth the price too, he definitely has got Freddie chips.

[Rybags]

Rusty brown is usually the power-up colour when an XL starts, in the brief time before the OS clears the hardware registers.

 

At least then you should have a working GTIA.