TOS206 Decoder MMU Plugin not working

[Emwee]

Hi,

today I soldered my TOS 206 Decoder (MMU Plugin -> https://www.exxosforum.co.uk/atari/store2/#0248 ) and the Mega ST Dual TOS PCB ( https://www.exxosforum.co.uk/atari/store2/#0008 ).

The Dual TOS board works, I've tried it without the Decoder and the Jumper set to TOS 1.04, system works as expected.

Then I plugged in the Decoder and my system just stays with a grey screen, nothing happens.

This is how it's soldered an placed top of the MMU:

Decoder_01.jpg (726.4 KiB) Viewed 2560 times

Decoder_02.jpg (767.92 KiB) Viewed 2560 times

Decoder_03.jpg (715.92 KiB) Viewed 2560 times

Decoder_04.jpg (728.5 KiB) Viewed 2560 times

Decoder_05.jpg (747.41 KiB) Viewed 2560 times

What have I done wrong?

Many thanks,
Markus

[exxos]

It's supposed to plug over the GLUE..

Also you will need to cut the CE pin to the MB on the dualtos boad.

[exxos]

Now got me thinking viewtopic.php?p=94115#p94115
Clearly on the glue on the H5 but all my info says MMU

[Emwee]

well, yes

Tried it over the GLUE, unscrewed the PSU and placed it a bis aside, also doesn't work - even if it would work : you'll never get the Mega ST put together again, because the GLUE is under the PSU and it all gets to high.

[exxos]

Did you cut the CE pin ?

[Emwee]

Yes, it is removed.

[rubber_jonnie]

Sounds to me like a bad contact in the socket area, how far in was the decoder pushed?

[Emwee]

As far as it goes, I'd say complete.

[exxos]

I suggest fluxing the pins and reflowing them under a magnifier as a lot of the soldering doesn't look great. Also make sure you don't have any shorted pins.

In particular the highlighted pins as these are the important ones.

Capture.PNG (80.03 KiB) Viewed 2494 times

I would also return your machine back to stock and make sure it still boots up before doing anything else! Inserting the plugin boards can result in bad connections on the MMU. The socket pins may need to be adjusted.
viewtopic.php?p=16092#p16092

[Emwee]

Returned to stock all works fine, will reflow the pins later.

But where goes it in? MMU? Or GLUE? If GLUE, then I'll give it a try, but it can't be used at the Mega ST.