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 Post subject: [HD-M20] Hitachi Muse Decoder
PostPosted: 31 Oct 2017, 04:46 
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I recently got a Hitachi Muse Decoder HD-M20 (clone of the Pioneer HM-D101) because of it's supposedly better decoding capabilities than my Sony MSC-4000. Unfortunately, it only worked sporadically for a few minutes.

The issue --- I only was able to briefly output a component signal and it did look better than the MSC-4000, less green smear. The unit still powers on, but I don't get any video output anymore. The "Muse" indicator light no longer comes on. I checked all connections and they seem fine. I hope/believe it's a capacitor issue given the age of these electronics. By any chance, do we have any board members who are good with capacitor replacements?
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 31 Oct 2017, 05:47 
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Lucky you, to get your hands on one of those! That's a model I haven't been able to get.
First question, have you checked the power supply voltages? If the power board is well designed, they should be called out on the board itself. Signal coupling capacitors could be a problem, but I'd go after the power supply first (especially because it has big electrolytic capacitors that might well have gone bad).
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 31 Oct 2017, 14:30 
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Both congratulations on picking one up :D , and commiserations on the issue you're having :cry: . Was this the one on YJP that the seller had an MSC-4000 in the same photo they were also selling?

Just on the off chance did you try one of the muse inputs other than the one actually labelled for LD? (They all work for LD input too). Otherwise the power supply sounds like a reasonable and fairly straightforward place to start at least. Though like you say it does power on, but no Muse signal detection. I have a HV-MD2 where the picture/muse signal dropped out intermittently which turned out to be a dry joint on what looked like a transistor but got pretty warm so was probably a power regulator. Dry joints also caused problems on my SP-D07 so worth checking for.
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 01 Nov 2017, 00:13 
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Thanks Publius and Audioboyz1973! Yes, this was the one listed on Yahoo Japan. I saw it for 25,000 yen passed on it, then the seller listed at 40,000, finally he relisted at 25,000 so I bit.

I did try the other Muse inputs and same result. There is only a gray image/signal coming out. And the Muse indicator light no longer lights up as it did before.

I opened up the unit and took some pictures. Here is the google drive link if you want to check it out. I highlighted one capacitor(?) which seems a little misshappened than the others, wondering if that might be the culprit.

https://drive.google.com/open?id=0B_AP8 ... llzeXdWLWc

Having had a capacitor go out in some of my other electronics, I know there's a fishy smell, but I didn't notice any with this unit. Also used a step-down transformer always with both my MUSE decoder and HLD-X9.

My soldering/electrical skills are non-existant. Hoping there's someone stateside who might be able to help. Thanks again for the responses, much appreciated.
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 01 Nov 2017, 01:34 
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What you've circled in red there isn't a capacitor at all. As its code beginning with "L" indicates, it's an inductor : a coil in a can. Those virtually never fail, but when they do it's very easy to tell, because they open-circuit.

¥25k to have it just quit is definitely a bitter pill. I make no representations at all as to my ability to fix it, but if you don't get any better advice or offers, you could send it to me & I'd try my best.
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 01 Nov 2017, 05:22 
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Though I can hold a soldering iron my technical knowledge of electronic repairs is limited to say the least.
Just from seeing his posts and Muse site Publius is far more knowledgeable.
If he ends up attempting a repair I'd be more than happy to open mine up and take any measurements he might need for reference from a working unit?
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 01 Nov 2017, 06:49 
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audioboyz1973 wrote:
If he ends up attempting a repair I'd be more than happy to open mine up and take any measurements he might need for reference from a working unit?

Yes, in the absence of a service manual (I've never seen one for a MUSE decoder) comparison data are vital!
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 01 Nov 2017, 16:47 
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Unless there is some way to get into a test mode you will need to get meters out and go old school, but that will only tell you if its electronic not internal from chips etc.
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 02 Nov 2017, 19:43 
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Thanks everyone, this board really rocks. Fingers crossed. Publius, I'll be PMing you shortly to discuss details as I'd like to take you up on that offer!
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 Post subject: Re: Hitachi Muse Decoder HD-M20
PostPosted: 21 Oct 2021, 06:17 
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As mentioned in laserfanhld-gb @ [HM-D101] Just received there is a HD-M20 on eBay right now so I'll take advantage of it and post the pictures here for reference.

First Hardware Database draft: Hitachi HD-M20

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 Post subject: Re: [HD-M20] Hitachi Muse Decoder
PostPosted: 10 Dec 2023, 06:34 
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Found a Hitachi PDF with Hitachi HD-M20 (and Hitachi HD-M10) details from their January 1993 internal newsletter.

Quote:
New MUSE decoder with lower price

Because HDTV has a higher resolution it can contain several times more information than current television systems. Therefore the "MUSE protocol" is required, which compresses the signal, broadcasts it, and then decompresses and plays the received signal on the receiver.

We reduced the number of signal processing circuits, which were previously compose of 150 LSIs, to approximately 30, improving performance, reducing size and weight (from 7.6kg to 5.6kg), and reducing power consumption (from 65W to 36W) and lower prices (from standard 1,750,000 to 750,000 yen).


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 Post subject: Re: [HD-M20] Hitachi Muse Decoder
PostPosted: 29 Feb 2024, 11:04 
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Turns out there was a professional Hitachi HD-M10 before the HD-M20.

But we know very little about it.

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