Found Memotech MTX PSU

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protek

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Ok, this is a really loooong shot but I have a Memotech MTX500 that is missing a PSU, so I'm looking for one.
 

Bryce

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I've just posted this in the other thread, but... Making one should be relatively easy to do (a lot easier than finding an original).

Bryce.
 

protek

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I've read about it in the MTX Forum, if that's the one you mean. I'm just having bit of trouble understanding how the replacement can output both AC and DC whereas the original outputs only AC. To my understanding, the new PSU doesn't require any modifications to the MTX itself.

I've registered to MTX Forum to ask about it but my account hasn't been approved yet. Maybe I should ask Mark about it over at WoS.
 

Bryce

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I haven't actually seen a design for a replacement PSU anywhere, can you post a link to it? In some cases it's ok to supply DC instead of AC, so it's not unheard of. However it requires more unnecessary hardware and cost. If I was designing one I'd use AC only. It could be built relatively cheaply, even if it needed 2 transformers.

Bryce.
 

protek

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Bryce

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Bryce

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That was just the first suitable transformer I could find. You'll probably find a similar one for cheaper if you shop around. Important is that it goes up to at least 24VAC at 1A and has taps every 3VAC.

Bryce.
 

protek

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Is 1A enough? I know that the original Memotech PSU was rated for 1A but it sounds a bit slim, unless you keep your setup vanilla.
 

stevendt

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I've registered to MTX Forum to ask about it but my account hasn't been approved yet. Maybe I should ask Mark about it over at WoS.

Sorry for the delay, but you have now!

it would be good if you could ask MTX related questions over on the Memotech forum

regards
Dave
 

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Is 1A enough? I know that the original Memotech PSU was rated for 1A but it sounds a bit slim, unless you keep your setup vanilla.

It's 1A at 30VAC, which means that you could technically pull 3.3A from the 9VAC rail or 2A from the 15VAC rail etc. From what I've read in the links you posted, the 18V (15 in this case) only pulls 820mA and the 9V is only pulling 280mA (although this seems wrong). Either way, the one I linked to has about 36% more reserve that the original. You can go higher, it just makes it bigger and more expensive.

Inside the MTX you have a 7812 regulating the 12V. This can handle max 1A but I doubt it gets anywhere near that. The 5V rail is regulated by a 7805 - 1A max, this is probably the biggest load and the -5V regulated with a reversed Zener diode, so it can only be pulling a few mA.

Bryce.
 

TheCorfiot

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I've registered to MTX Forum to ask about it but my account hasn't been approved yet. Maybe I should ask Mark about it over at WoS.

Sorry for the delay, but you have now!

it would be good if you could ask MTX related questions over on the Memotech forum

regards
Dave


Why Dave
Amibay is a multi platform forum, you can't ask people not to post here regarding the MTX.
Quite a few of us own MTX's too.

TC :)
 
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protek

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Good call! Didn't realize it was that big. :LOL:
 

protek

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The seller of the MTX told me that he has possibly a suitable generic multitap transformer stashed away that I can have. Will see how that turns out.
 

stevendt

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Actually, I didn't ask people NOT to post MTX questions here, I just said that "it would be good if MTX questions were asked over on Memorum". Yes, a few people here may have MTXs, and a few people over on Memorum may be members here too, but the majority of people active in the (very, very small) MTX community are registered on Memorum, the advantages of asking, or even duplicate posting, over there are :

It is much more likely that you will get a response from a Memotech "expert" (bad choice of word, but hopefully, you know what I mean)

The question and its answer(s) could be relevant and helpful to other MTX owners, so posting there, other MTX owners are much more likely to see it and be able to benefit

Regards
Dave


I've registered to MTX Forum to ask about it but my account hasn't been approved yet. Maybe I should ask Mark about it over at WoS.

Sorry for the delay, but you have now!

it would be good if you could ask MTX related questions over on the Memotech forum

regards
Dave


Why Dave
Amibay is a multi platform forum, you can't ask people not to post here regarding the MTX.
Quite a few of us own MTX's too.

TC :)
 

protek

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Just placed and order for the transformer linked by Bryce. Once that arrives, I have to start putting it together.
 
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