Atari 520STFM - L51 Inductor

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Riskyflier
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Atari 520STFM - L51 Inductor

Postby Riskyflier » Tue Sep 26, 2017 9:13 am

Hello,
Could anyone let me know where I can find a replacement Inductor (L51) please?
I'm in the UK
I have a few ST machines and this particular one is the cleanest. But its the only one that doesnt work.
When the power supply is switched on - L51 lights up like a Xmas tree!
The power light comes on Green, and I get interference on the monitor.
Before I go and trouble shoot this issue it would be great to know If there is a replacement I could use.

Many Thanks

Atarieterno
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Re: Atari 520STFM - L51 Inductor

Postby Atarieterno » Tue Sep 26, 2017 11:03 am

If you are in the UK you have several well stocked STfm stores, such as eXxos or ST-Freakz.
Ask them.
ST/fm/e, STacy, Mega ST/e, TT, Falcon, C-Lab MKX... and more music tools.

Riskyflier
Atarian
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Posts: 2
Joined: Wed Sep 07, 2016 5:55 pm

Re: Atari 520STFM - L51 Inductor

Postby Riskyflier » Tue Sep 26, 2017 11:11 am

I'll ask them...
Many Thanks

siriushardware
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Re: Atari 520STFM - L51 Inductor

Postby siriushardware » Wed Oct 04, 2017 5:33 pm

If L51 is glowing, just fitting another L51 will only damage the new L51.

Your actual problem is a short-circuit on the 5V supply rails beyond L51. On the circuit diagrams I have, L51 is shown upper left on sheet 5 of 5 - it is an inline filter on the +5V supply rail. The only thing which could cause that to burn up would be a very low resistance down to ground from the 'filtered' side of L51. The fact that L51 is shown on the memory section of the diagram suggests that it filters the +5V supply to the memory, and that the problem is therefore in that area. Unfortunately that's about the worst area you could be looking for a short on the supply rails - it could be any of the memory ICs but it could also be one of the supply decoupling capacitors short-circuit - there will be one next to every memory IC.

If your memory ICs are soldered in (not in sockets), well, a memory IC has many soldered legs and a capacitor has just two. Guess which components you should check first?

You will need to find that short before replacing L51.


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