Hi there, I'm currently in the process of repairing a WM-D3 w/ no sound at either Line or Headphone amps, and have removed and opened the DC-DC converter hoping to replace components inside. My understanding is that this converter functions to take 3V and boost it up to ~8.2V (according to the Service Manual schematic), enabling the audio amps to function properly. Unfortunately the schematic in the manual simply shows the DC converter as a single component, CP301, without detailing what's inside. I've been able to find information about the DC-DC Boost converter used in the WM-D6C - which I think has also been labeled by Sony as CP301 - but nothing about the converter in my WM-D3. So, I'm having a tough time identifying the following components, and was wondering if you would know acceptable replacements for each - Zener diodes (2x) Schottky diode (1x) Transistor Inductor Resistor (2x) The electrolytic capacitors I can figure out, but if anyone has a list of parts based on having worked on these in the past, or an understanding of the values needed in each component for the converter to function - the more information the better! Included some pictures - while there are arrows in only some of the images, I'm interested in confirming all of the components. Thanks again! John
I reckon you should check the schematic in the WM-DC2 service manual. Reason being the converter in the D6C is 6V to 11V and what you need is more likely 3V to 6V, like the DC2. The converter in the DC2 boosts the voltage to supply the line out amplifier.
Thanks for the tip @mattb1970 - I'll check it out! For the WM-D3 it's a 3V to 8.2V, but I'm sure there's something to glean from the DC2 schematic. And thank you @Silver965 ! I assume that this schematic, while shown here for the WM-D6C (6V to 11V), would be the same for the WM-D3 (3V to 8.2V) albeit using components w/ different characteristics from those in WM-D6C converter? i.e. a zener diode with a different backwards voltage, perhaps a different value inductor, Schottky diode, etc. etc. When designing these DC-DC boost converters, is it the case that the backwards voltage of the Schottky diode should match the target output of the converter? So in the case of a 3V - 8.2V converter, the backwards voltage of the Schottky should be 8V? 8.2V? 9V? I'm trying to work with an online calculator used for designing DC DC Boost converters, which has the following fields to populate - I estimated what I thought the Min + Max input and output voltages should be based on my earlier voltage tests of the WM-D3 board. Frequency I'm not sure about - and not sure how I'd go about finding out - so left as 31250Hz (default)......this may be completely off-base Output current draw I used the Playback current draw specified in the service manual Max allowable voltage ripple again I'm not sure about, so left as 0.1 (default) Any help in understanding how I go about finding these values to populate the calculator would really be appreciated! I'm sure that I'm greatly oversimplifying my questions, and if there's any additional information that would be needed I'm more than happy to try and provide. For now, I've included an image from the schematic showing the location of CP301 DC-DC Converter. Ultimately I'd like to be able to put together a list of compatible replacement components to be used in the DC-DC Converter for the WM-D3, in order to hopefully help out others also interested / in need of this info down the road. Thanks, John
The DC2 outputs 7.9V so it's very similar to the D3. The diode will be rectifying the stepped-up AC voltage, it's not working as a regulator. Remove it from the board and check if on diode check it only conducts in one direction. The capacitors are polarised so if the DC supply has been reversed at some point they may have failed.
I was about to say I get lost with transistor circuits like that, although looking at the voltages it is fairly obvious there should be 7.25V across the zener diode which I would guess is a 7.2V device. My first comment was going to be that if you get really stuck there are now dozens of small switch mode ICs from the likes of TI to do the same job. Those USB recharge your phone packs that you get in Poundland contain a switching IC to boost the 3.6V lithium cell up to 5V.
the scheme published by mattb and with three transistors and a single diode ... but in john's photos I see only 2 transistors and 3 diodes ... it is true that the d6c scheme is for different voltages but they are 2 transistors and 3 diodes .. it could be more like .... afterwards you can take anything to be successful
The thru-hole transistor is a 2SA1013 PNP. All the transistors in the DC2 DC-DC converter are NPN so that design is different. The D6C DC-DC converter has both an NPN and PNP transistor so it's possible this design is closer to that of the D3. The thru-hole components that look like resistors, next to the IN and OUT labels are most likely inductors. Check for continuity across their pins to determine if they are faulty. There is a 2nd surface mounted transistor on the solder pad side, unfortunately I cannot identify it. There are also 5 surface mounted resistors and a capacitor on the solder pad side. In case you haven't already seen it, this excellent post gives some very useful info about the D6C DC-DC converter design; http://stereo2go.com/forums/threads/wm-d6c-dc-dc-converter-fixed.421/
in fact it seemed strange to me to mount 2 old 1/4 watt resistors ... Brown green ... gold? and the other Brown red and I don't understand if it's yellow or orange .. I'm rusting too
I remember my resistor colour codes but less certain for inductors. Anyway, that thread I linked to confirms the component by the IN is a series inductor on the D6C DC-DC board so I guess it's the same for the D3. It makes sense anyway! My approach would be to remove the inductors and measure for continuity. Remove the diodes and transistors and do a diode check with a multimeter and replace the 2 electrolytics. Do all this then test if it works.
First off - @Silver965 , @mattb1970 , and @Longman - thank you all for the fantastic information! Sincerely appreciate it. I'll definitely be performing the tests described by @mattb1970 to make sure everything's working correctly, or if not which component(s) having problems. I'm currently away from home, but returning this weekend and can report back on findings. Identification of the various component types is really helpful. It looks like the best way forward in terms of understanding the values of each diode, transistor, inductor, etc. will be reviewing the WM-D6C converter design, and trying to apply that design here. A couple of additional thoughts, which you can all feel free to take or leave - would hate to overstay my welcome.... For @mattb1970 or anyone else familiar with how these circuits are designed, I assume that the voltage difference between the D6C and D3 means that the values of components used in each will change - at least for the Zener and Schottky diodes. Right? Now that we know the types of components being used, does that mean we also know the values of each component, in case I need to replace a diode, inductor, or transistor on the board? Looking back at the circuit design calculator, I'm wondering if you might know how I can approach the following as they relate to the D3 DC converter: How to know required input and output wattage? How to know required input and output current? What will be the "switching frequency"? - started reading up on this yesterday, but still not clear on how to identify that frequency here Ultimately I'm hoping to be able to reverse engineer the converter so that I understand not just the types of components, but the values of components used as well. Once again, a HUGE thank you to all! John
The circuit designs might be the same but the component values will most likely be different. No we can't identify the component values unless you measure them. I would focus on getting it working first then reverse engineer it. You may be able to test the surface mounted transistor without removing it from the board. Use a multimeter set to diode check to test it. Caps, diodes and possibly inductors can fail if the DC-DC converter is powered reverse polarity, that's what tends to happen with the D6C as the DC in jack is centre negative (opposite of vast majority of DC adapters).
Unless you are colour blind, the majority of through hole components can be identified from their markings. You have already mentioned resistor colour codes. Look closely through a magnifier and you will probably find a number indicating the voltage on it somewhere. Ceramic capacitors will usually have a number, often in the same format used for resistors showing the capacitance in pF e.g. 103 = 10 000 pF. Unfortunately, if surface mount components have any markings at all they are usually cryptic codes.
Hi, I am new to this forum. I just find out that the transistor of the D3 DC converter is 2SD1012 PNP. And the inductor is 33UH - 300K 0.125W or bigger. My D3 was wrongly plug in 7V dc to cause both burn out. After replaced the two I got the 3v output and 8.7 v output from the DC converter. Hope it can help. Thanks
@JoFugd You do need to repair the existing DC-DC converter. Designing a boost converter that takes 3V in and outputs 8.2V is very simple with today's controller ICs, as @Longman said. Some of them have the switching transistor and diode integrated so you will only need an external inductor, some capacitors and a voltage divider for the feedback. However, there is one big problem: the typical design will have very high ripple for this application. SONY achieved the very low ripple and simplicity by using a custom transformer: they afforded to do that because they built hunderds of thousands of these units. In order to achieve the same performance you will either need a controller that is specifically designed for low ripple (which will require a higher component count) or use additional filtering (inductors and capacitors). Either way, both the cost and the footprint of the circuit will grow. You will also need to design a PCB for the new circuit, as almost all newer controllers are SMD, some in very small and hard to solder by hand packages. My opinion is it's not worth the hassle, because repairing the existing one is a much simpler option. I would check the active components first (diodes and transistors) as they're the most likely to have gone bad. The small inductors (those that look like resitors with color codes on them) can go open. I will leave capacitors last, as they're the most unlikely to have a problem, especially the SMD ceramic one (judging by its size its probably in the order of few hundred pF). If you find the diodes to be bad, look if they have markings, you may be able to find more info, even a datasheet. You also have the chance to reverse engineer this DC-DC converter and make a schematic for future reference. Good luck !
