Philips MCD-139 Modification / Hack

Hi there,

Recently I acquired a Philips MCD-139; this is a 2.1 DVD / micro system.
The trouble is, I do not have the DVD/Micro system component. What I do have is the Subwoofer, Amplifier (integrated into the Left channel) and the Right speaker.

There is a 9-pin DIN connector which would (under normal circumstances) connect the Micro unit to the amplifier/speakers. I figured that all this cable would do is:

1. Provide the input sound
2. Control the volume

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Step 1:
I started investigating which pin goes where.
As per the photos above, I created the following diagram to easily track where each goes.

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Pin 1 (Surround) - A + D (Common / Ground)
Pin 2 - E + F
Pin 3 - E + F
Pin 4 - H
Pin 5 - A + D
Pin 6 - G (Sub?)
Pin 7 - A + D
Pin 8 - B (Right?)
Pin 9 - C (Left?)

Connectors E & F have 5v coming down them when the power is plugged in.

Any advice / suggestion as to where to go from here?

Thank you in advance

I realise all that may not have been terribly useful; I've been looking into it more, and have come up wtih this:

On the board, which houses the DIN connectors and Amplifier module, there is a ribbon cable which connects, coming from the main 'power supply' component of the system:

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A couple of 'GND' signals, and '5v' rails, along with a '24v' one. The thing that caught my eye was the one marked 'STB' (Set Top Box?).
I figured this might be a connection that turned the main power on and off.
This PIN is linked to PIN H in the previous diagram.

The other side of the ribbon cable (on the power supply end) is like so:

**broken link removed** There, the same cable is marked 'ON/F'. I believe this is the final piece of the puzzle, required to 'switch on' the actual unit.
Any further thoughts / opinions appreciated

the STB connection is for standby on off switching which will either be active hi or lo going to bring the powersupply out of standby or to switch to standby.............

Thanks for the input, Sheldonstv.

I went further to find out if there was a 'way' in which to switch this to 'constant on' somehow. I figured the best way would be to see where that wire actually leads.

On the underside of the Power Supply board, it also had the markings of what the different cables meant from the ribbon cable.

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I traced the single track from the connector marked "ON/F"...

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...and found it lead to here (on the topside):

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Where it would appear a whole segment of electronics is missing.

I made sure it wasn't a multi-layered PCB, and used a multimeter to see if this circuit popped up anywhere else on the board - so far as I could tell, it did not.

Could this potentially mean that it's an 'always on' circuit?
Or just that I managed to get a 'dud' demo-esque unit?

oldskool said:

Where it would appear a whole segment of electronics is missing.

I made sure it wasn't a multi-layered PCB, and used a multimeter to see if this circuit popped up anywhere else on the board - so far as I could tell, it did not.

Could this potentially mean that it's an 'always on' circuit?
Or just that I managed to get a 'dud' demo-esque unit?

Click to expand...

It's commonplace to use the same PCB for a range of models, the missing parts will be fitted in a higher spec model, that's all.

micro unit

Hi oldskool.
I have the micro unit. Would you like to sell your speakers or buy the unit?
Can you repost the diagram for the din pinout? That way I could power the unit to test it.
Thanks.

Forumn

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This is a forum of users for this system.
The last posting is a while back, but maybe someone will have some useful info.

nevermind. got 2 bulging capacitors ):
$5 at a thrift store. LOL.

Hi, I've got a MCD 139B Amplifier and Speaker System, but same as the original problem above, I don't have the DVD system component. so to make use of the stuff that I have, I want to connect my Computer Audio out to the amplifier directly.

with this image View attachment 62919 posted above, I think mine is a little bit different because it has those missing parts. I need help how to connect my computer audio. I don't have any electronics background. All I have is a soldering gun. Really appreciate all the help I can get! thanks a lot!
View attachment 62917

View attachment 62918

can i connect an aux cable through the 8 pin mini-din ?

Dear friends. i am writing from Spain. I have got a problem with the unit. One resistor R937 is burnt, but i could not find any service manual with the value. I put another power supply with 24v and 5v, but now no sound from the system. The only cable i do not connect, is the on/off. Can you help me with the value of that resistor o tell me how to connect the cable on/off in the power supply?
Thanks.

I've got the same problem, I've got Phillips MCD-139 without DVD unit and I woudl like to connect laptop directly to power amp. I found schematics of power amp & psu:



I put signal on input but nothing happens, I belive amp is stand by mode. Coudl somebody tell me how to turn it on? Laptop has only R out & L out, power amp has R in, L in & SUB in, where can I find signal for sub in?

I recently aquired the dvd player to the discussed phillips system. It appears to be in good condition. I'd like to purchase the speakers that go with it as I could use a decent 2.1 system or secondly, part with it to someone who is in need of it.