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by mikro
Mon May 11, 2020 8:08 pm
Forum: PSU (power supplies)
Topic: How to: recapping the Mega STe power supply
Replies: 68
Views: 15671

Re: How to: recapping the Mega STe power supply

What a great guide! There is an error with C14 - it doesn't have + on the left on and - on the right but - on the top and + on the bottom. Just a note, this is still wrong in the picture. Also, when upgrading the PSU, make sure you have insulated the nut in the middle (and not used the bolt again),...
by mikro
Mon May 11, 2020 11:25 am
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

czietz thank you for the test & confirmation, I had no idea that is normal to have such temperature on a electronics component, wow. Yesterday I checked all the rails, I couldn't see anything suspicious. It's true I had only the poor man's tool for detecting ripples, i.e. min/max but it seemed all ...
by mikro
Sun May 10, 2020 7:57 am
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

It ges more and more interesting. While I had the MegaSTE PSU in TT, I was thinking let's try the other way around - so I put the TT PSU in the MegaSTE. And to my surprise, the PSU behaves totally differently - the regulator is nowhere that hot (I would say warm at best) and of course no restarts. W...
by mikro
Sat May 09, 2020 11:54 pm
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

As it is getting late I didn't have time for something serious so I just tried one more thing - MegaSTE PSU in the TT. And, as you would have guessed, it not only works but the regulator is freaking hot as well. But 1,5 hours later everything still works as it should. So that makes my initial suspec...
by mikro
Sat May 09, 2020 9:44 pm
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

Thank you for the effort, though. :) I'll try to investigate further in the meantime. What can I say with a certainty, it definitely seems that the lesser devices / CPU activity, the better. Just staring at empty desktop makes the computer more "stable" (but the regulator is still super hot). With a...
by mikro
Sat May 09, 2020 9:26 pm
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

I guess you don't have your TT open so you could check whether your PSU's regulator is getting so hot as well? It's so hot you can't even touch it for longer than half a second.
by mikro
Sat May 09, 2020 9:09 pm
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

... and we can safely rule the Storm out, it has rebooted shortly after I posted the last update. :)

Incidentally, I am running YAARTTT as a check whether it has restarted, *when* it was running memory errors were always zero.

Going to look at the -5V rail, thanks for the tip.
by mikro
Sat May 09, 2020 8:55 pm
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Re: Atari TT's LM7905CT getting too hot

Intermediate result so far - when I disconnected the Storm, the computer seems to be much happier, no reboots so far (about 30 minutes). Mach64 (but not the NOVA adaptor) has been disconnected the whole time, just to be on the safe side.
by mikro
Sat May 09, 2020 8:27 pm
Forum: PSU (power supplies)
Topic: Atari TT's LM7905CT getting too hot
Replies: 22
Views: 1152

Atari TT's LM7905CT getting too hot

I have had a TT for some time but I haven't really used it for longer periods of time. Just installed the Thunder/Storm, then Lightining, then NOVA/Mach64 and all seemed fine. Sometime during those times I have also recapped the PSU with the Exxos kit + replaced the CNY17-3 opto-isolator with a PC11...
by mikro
Fri May 08, 2020 6:30 pm
Forum: ELECTRONICS
Topic: Switchable SCSI termination
Replies: 9
Views: 557

Re: Switchable SCSI termination

Leave the falcon termination in place, plug a SCSI termination into the falcon SCSI port on the back of the falcon, remove termination from the CosmosEx and connect it internally to the SCSI bus and all should be fine with or without the CosmosEx. The SCSI interface is designed to drive two termina...

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