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iFi Audio Model "micro iPhono2": Creating Schematic - help needed
iFi Audio Model "micro iPhono2": Creating Schematic - help needed
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Old 2nd August 2018, 09:49 PM   #1
tiefbassuebertr is offline tiefbassuebertr  Germany
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Default iFi Audio Model "micro iPhono2" (iphono-2): Creating Schematic - help needed

Currently I am creating a schematic diagram of this MM/MC RIAA head amp:
micro – iPhono2
iFi iPhono 2 | The Ear
Review ifi iPhono 1 & 2 (und eine kleine Warnung) - Phonovorstufen und Ubertrager - Analogue Audio Association

For all used IC's I don't find out the right type number and thus I don't find the associated datasheets (except U3/U4: HC4066A in the TSSOP-14 outline = MC74HC4066A):

U1: EAA 5SA (SOT23-5, go to last image), unknown, maybe MAX828
U2: OV 4627A - maybe quadversion of Burr Brown's OPA 627 made for iFi-Audio (TSSOP-14, go to first image)
AMR/iFi audio's Content - Page 2 - Computer Audiophile
U5: OQ = H05 or 0Q = HO5 (SOT23-6, go to second image) - unknown.

Who can find out this for me ?
Thank you very much.

This URL's don't provide the wanted information:
http://chip.tomsk.ru/chip/chipdoc.ns...rt=1&count=500
http://www.dl7avf.info/charts/smdcode/cj.html#TOC
http://www.marsport.org.uk/smd/mainframe.htm
E96 codes SMD resistors
https://learn.sparkfun.com/tutorials...istor-markings
Transistors:
http://www.dl7avf.info/charts/smdcode/c2d.html
Q1 12T = 2N7002
Q2 2X = 2N4401
Q3 3FW = BC857B/BC557B
Q4 2XZ = ?? maybe 2N4401
Q5 38W = PMBFJ108/J108, Made in China - go to page 2 of 9 under
https://www.nxp.com/docs/en/data-she...8_109_110.pdf?
Q6 1BW = BC847B/BC547B
Q7 12T = 2N7002
Q8 12T = 2N7002
Q9 12T = 2N7002
Q10 2X = 2N4401
Q11 NU
Q12 12T = 2N7002
Q13 2X = 2N4401
Q14 12T = 2N7002
Q15 38W = PMBFJ108
Q16 6g = BC818-40/BC338-40
Q17 6g = BC818-40/BC338-40

Diodes
D1 WL = Zener 15V
D8 T4 = 1N4148
D7 SV = Zener 3V6
D9,10 WB = Zener 6V2
D5/D6: J11 923B = Zener, 8V2
https://www.onsemi.com/pub/Collateral/1SMB5913BT3-D.PDF
basics for iFi’s revolutionary ‘TubeState’ design
https://ifi-audio.com/portfolio-view/pro-idsd/
https://ifi-audio.com/portfolio-view/x-xdsd/
Attached Images
File Type: jpg DSCF3757.jpg (984.1 KB, 448 views)
File Type: jpg DSCF3763.jpg (911.6 KB, 435 views)
File Type: jpg DSCF3769.jpg (979.0 KB, 428 views)

Last edited by tiefbassuebertr; 10th September 2018 at 07:34 AM.
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Old 2nd August 2018, 10:09 PM   #2
billshurv is offline billshurv  United Kingdom
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iFi Audio Model "micro iPhono2": Creating Schematic - help needed
You want help reverse engineering a commercial product?
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Old 5th August 2018, 10:42 AM   #3
tiefbassuebertr is offline tiefbassuebertr  Germany
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Quote:
Originally Posted by billshurv View Post
You want help reverse engineering a commercial product?
Most important thing for me on a commercial product is in general the wish, to understand the theory of operation in detail. Unfortunately this is impossible without a schematic diagram. OTOH - most exist schematic diagrams from today's available audio devices wasn't release, because this diagrams are confideltial in most cases.

But in this case only the information concerning the used semiconductors U1 and U5 from the internal SMPS regulator with SMD marking code "EAA 5SA" and "OQ = H05" or "0Q = HO5" is important for me (I am already owner of this RIAA preamp device).
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Old 9th August 2018, 08:15 AM   #4
tiefbassuebertr is offline tiefbassuebertr  Germany
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Unfortunately no support from the experts here - I have find out this:

U1 (Device Code "EAA": Onsemi MAX828 (DC-DC Converter)
https://www.onsemi.com/pub/Collateral/MAX828-D.PDF
datasheet MAX828EUK

U5 (Device Code "OQ", Outline TSOP-6): Richtek R7731GE (PWM Flyback Controller)
https://www.richtek.com/assets/produ...S7731-03QV.pdf
http://www.s-manuals.com/pdf/datashe...31_richtek.pdf
R7731 - Burst Triple Mode PWM Flyback Controller | Richtek Technology

Under
http://www.s-manuals.com/pdf/datashe...31_richtek.pdf
I read this:

For device code information, contact our sales representative directly
or through a Richtek distributor located in your area.


But I have found this:
SMD Marking Code (Marking Information, Marking Diagram, Device Code) - go to page C-7 under
https://www.rom.by/files/Richtek_Marking_Code.PDF

Different package naming for the same outline: SOT23-5 = SC-74a = SOT753 = TSOP-5
https://www.nxp.com/docs/en/package-...ion/SOT753.pdf

The actually supply voltage for the input stages and RIAA stages are create by internal SMPS DC/DC concerter.

This provides the great addvantage, that both the quality and technology (both 50/60Hz or SMPS) of/in the outdoor wall power plug haven't any influence to the sonic character. Even a high proportion of disturbances in the power grid haven't any influence through this approach.
OTOH - the quality of the internal SMPS defines the highest achievable quality in sound.

Maybe the disconnect of the internal DC/DC converter and connect with a shunt regulated power supply version like that one under
The simplistic Salas low voltage shunt regulator
is the right way to enhance additional the sound quality.

Last edited by tiefbassuebertr; 9th August 2018 at 08:24 AM.
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Old 11th August 2018, 04:51 PM   #5
nRm is offline nRm  Argentina
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I watched your first link:

micro – iPhono2

and got very intrigued about this:

"To DC Infinity and beyond. The all new 'DirectDrive® Servoless DC Infinity' circuit has no capacitor and no DC-Servo meaning no noise and no distortion."

Is that for real? No cap, neither DC servo? How is that done? Through insane matching?
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Old 12th August 2018, 04:00 AM   #6
PRR is offline PRR  United States
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> Is that for real?

It is not even wrong. Just nice-sounding words. There's no reason a cap or servo should add noise or distortion.

It may be a finely engineered box. But their words-writer was smoking something else.
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Old 12th August 2018, 08:20 PM   #7
nRm is offline nRm  Argentina
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Anyway if there exists an autozeroing topology without caps neiter servo, it is interesting.

tiefbassuebertr let us know, please.
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Old 17th August 2018, 10:31 AM   #8
tiefbassuebertr is offline tiefbassuebertr  Germany
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I think, a creating of schematic is impossible, because the used marking codes on the transistors are custom made, at least partly.
According the marking codes under
Marking smd
at the MC input stage operates a small signal N-Ch MOSFET (NXP 2N7001/12t) and a small signal NPN BjT (ONSEMI 2N4401/2x) in parallel mode. I doubt very strongly, whether this is possible.
The use of custom made marking for smd devices is a really good prevent for unauthorized clones resp. copies.

Last edited by tiefbassuebertr; 17th August 2018 at 10:33 AM.
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Old 18th August 2018, 12:27 AM   #9
nRm is offline nRm  Argentina
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Can you tell us something about the suppossed autozeroing topology?
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Old 18th August 2018, 12:51 AM   #10
rayma is offline rayma  United States
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Quote:
Originally Posted by tiefbassuebertr View Post
at the MC input stage operates a small signal N-Ch MOSFET (NXP 2N7001/12t)
and a small signal NPN BjT (ONSEMI 2N4401/2x) in parallel mode.
They're more likely to be in cascode, not in parallel.
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