On 8/15/2014 2:44 PM, Jay Ts wrote:
In terms of the circuit and performance, if you can get the printing on
the main chips, such as the codec, it can help identify the exact part.
From there, it's possible to look up the corresponding datasheet and
learn a lot about the quality of the product.
I could read it with difficulty, and I put the info about the codecs in
the review because I knew that some people were going to want to compare
what's used in this unit with what's used in some other unit, then start
a discussion on Gearslutz along the lines of "The $2,000 Lyra uses the
same converters as the $200 M-Audio (OK, I don't know if that's true but
you get the point) so why is it so much more expensive?
It's nice to see the brands of electrolytic caps in the power supply
section, too.
In order to do that on this unit I would have had to disassemble it even
further since the power supply, except for some vent slots, was pretty
thoroughly enclosed. I wouldn't expect a company like Prism would use
cheap components.
if the caps are Nichicon, United Chemi-con or Panasonic, just tell
people.
I've heard of those brands and if I notice them, I might mention them.
There was very little on the main board that's identifiable. I don't
know how to tell which of those little rectangular chips are resistors
and which are capacitors, much less the brand names.
In general for SMD chips, there are footprints that are so tiny that
virtually no human can solder them, but there are also older, larger
footprints (such TSSOP) that are just half of the 0.1" through-hole
packages from the 1970s that we all love. 
What part of "it's practically unrepairable" don't you understand? Do I
have to prove this to you? You're reading my review. Take my word for
it. If it was easy to repair, I would have mentioned that.
From what I'm seeing in the photos in the article, the first thing you
need to to is use brighter lighting so the light level on the case more
closely matches the brightness of the LED display. The LEDs are simply
overexposed, which will mess up the colors.
Tell that to Prism. I'd have to look at the review again, but I think
that all of the pictures were either screen shots or came from Prism's
"high resolution" press photo library. The reason why I tried to
photograph the meters myself was that I wasn't satisfied with the stock
Prism photos. You DID read the review, didn't you?
It's not always necessary to have an exact schematic or understand the
circuit completely. Often, designs are based on reference designs they
got from the manufacturer. I repaired my DMP3 just from looking at the
circuit board and discerning how the circuit generally worked, looking at
the INA163 datasheet, probing some pins to see that something was wrong,
and making a logical guess. It was easy.
OK, you can try fixing your Lyra when you get one and it breaks. Most
people who get into a failed device will look for a blown fuse or a
charred resistor. I can trace analog signals, but when it comes to logic
beyond simple gates, there's really nothing I can do to figure out
what's wrong. If your problem is with an op amp, yeah, that's not
difficult assuming you can remove the bad one and replace it without
buggering up the board.
If there are no custom proprietary chips, and you can identify all
of the chips, and look them up on Mouser or Digi-Key and order in
quantity of one, that's a big plus!
This ain't no $200 mic preamp.
I'm not really writing reviews for repair technicians who fix things
when they break, I'm writing for people who are going to use them and
hope that they don't break. To be honest, I'd take a crack at a mic
preamp that quit working, even if it was mostly SMD construction, but I
know my limits. I have a small Mackie mixer, a 402 VLZ3 I think, that
has a dead headphone amplifier. The way it's packaged, it needs to be
completely disassembled to even see the component side of the board, and
the chips are really packed closely together. I wouldn't take a chance
on screwing something else up trying to repair it. And for sure I'm not
going to get my soldering iron close to a $2,000 interface with a lot of
digital stuff on it. I might tackle the power supply if that was clearly
the point of failure (which isn't too difficult to determine) and it was
Sunday and I needed it for a session that night. But I've got good sense
and I'd send it back to the company for repair.
Look up "soldering smd" on YouTube. There are some really good lessons.
Yeah, like I'm going to trust myself to work on an expensive piece like
this with what I learned from YouTube? Nope. I have some ChipQuik and
have used that to remove a part and replace it when I could get in to
work on it, but I only chanced working on something I cared about after
removing and replacing a bunch of surface mount parts on a PC graphics
board that I picked out of someone's Free Stuff pile at a hamfest, just
to have something to practice on.
Look, Jay, I write these reviews because it gives an opportunity to play
with stuff that I wouldn't buy (either it's too expensive or I don't
need it) and I share them with those who are interested for all the fame
and glory that it gets me. It doesn't get me any money. If you've like
me to further into the design and construction, I'll be happy to give
you a quote. You have some valid questions, but you're very different
from the user for whom this gear was designed.
An Ampex AG-440 was designed for a different kind of user and was built
to be serviced (and in fact there are full schematics in the manual)
because every recording studio and broadcast station had a tech on board
or on call. This is not the case with today's studio gear, even units
such as the Lyra, that would be comfortably at home in any top tier
studio today. They just don't make studio techs any more like they did
in the Ampex days - because they don't make gear that way any more.
--
For a good time, visit
http://mikeriversaudio.wordpress.com