Source for Philips CD160 display?

[leadbelly]

I know this is a longshot, but since there are many out there in the EU, I thought I would give it a try.

I have a Philips CD160 which works perfectly except for a few burned out LED segments. On disassembly, it appears that there's no way to change individual 7 segment modules, they are made as 1 big subassembly. I did an internet search but the landed cost for a new one of those subassemblies here would be ridiculous.

Any other ideas/sources? Yes, I have considered just completely disabling the display as not to be distracted, and may wind up doing that.

[dnsey]

Are you sure that it's the display that's faulty? These players often have faulty display controller ICs, giving similar symptoms.

[Cobra71]

I know, this posting is a very old one but it's still interesting.

I own a CD160 with a partial broken display and I thought about tuning the CD160's sound and remove the existing display and change it with a 2*16 LCD Display that would be driven by a µP like the Atmega from Atmel.

Is there anybody aot there who knows something about the datastream between the "control and display Processor" and the Display?

I read that there is a 35Bit serial Data stream between them, but no further infos.




Cobra71

[gyro]

These displays do seem prone to failure. They were manufactured by National Semiconductor and based on one of their display driver ICs, and are no longer in production.

Luckily the serial interface is quite simple, yes it is a 35 bit interface with clock and data signal, actually it's 36 bits - the final clock is used to strobe the serial data to the output latches (first bit loaded is a '1' for this strobe).

I have a CD371, (which uses the same LED display as the CD160), and a CD472 which has a VF display. The 371,471, and 472 all use the same 'CD472 labeled' microcontroller, so the display interface is the same in each.

The CD472 uses an MM58248 VFD driver IC to drive its display, a quick search for MM58248 on Google will throw up the datasheet, including more explanation of the serial interface.

The only other information needed is the matching of the serial bit positions to display segments, from detective work on the CD472 this is as follows:

Bit 1 (Pin 18 on the MM58248, first bit loaded after strobe bit) = Digit 1 (Left hand) segment a, Bit 2 = Digit 1 seg b, 3=D1 seg c, 4=1d, 5=1e, 6=1f, 7=1g.

Bits 9 (note 9) to 15 are digit 2 a-g.
Bit 16 is the centre colon.
Bits 17-23 are digit 3 a-g.
Bits 25-31 are digit 4 a-g.

Bits 8, 24, 32, 33, 34 are for annunciators - on the CD472 for Pause, Repeat, Track/Time and IR. On the LED display, these bits come out as pins on the package to drive external LEDs. I'm not sure how these match up with the CD160, or which pin each comes out on, but this would be easy to work out at implementation stage.

Decoding with a micro should be quite easy - in fact it could be done with a few shift registers using the MM58248 logic as a guide. Speed shouldn't be a problem as this interface is bit-bashed by s/w in the microcontroller.

Hope this helps.

Gyro.

[Cobra71]

Many THX Gyro, you're a genius!
I will give it a try when I have a little more time.

If I further need a good detective i will call you ...

Cobra71

[Cobra71]

gyro> I looked at the 472 and it has a vacuum display instead led displays.

The CD160 uses a LED Board with 4 7segment led displays and a : in the middle.

On the back of the display there is a black glued chip that does the decoding.

The Display Unit is named NSM4202 and is be driven by a Motorola Chip with the following on its housing:

XC895070P
PHCD C03
A14T 8649

Thats the chip what gives the serial datastream to the display.
It uses three lines, CLK, DAT and Data Enable.
The chip also takes the switch informations from all buttons.

In the shematics it is called: Control and Display circuit, because thats what he does.

I took my oszi to the three points and a pulse lasts 0,05µs.


Cobra71

[gyro]

Cobra71,

Yes, the CD472 is Vacuum Florescent (VFD), my point is that that its serial interface to the Microcontroller (via the MM58248 VFD driver chip) is the same as the LED display (NSM4202 - a Nat Semi part number) used on the CD371. The same motorola 6805 microcontroller (marked CD472) is used on both these models.

The CD371 and CD472 also have a centre colon ( on the display, it is driven by data bit 16 as my last post.

I think the Motorola chip you found on the CD160 is also a mask programmed 6805 micro, used for front panel functions (button scan and display control).

I'm not sure about the data-enable signal, I think it's just an active-low enable on the data signal, probably used for multiple display configurations. There is no data-enable on the CD472, I don't have a schematic for the CD371, but I suspect that it is just tied low on the LED display on this model to give the 2 wire clock/data interface.

You ought to be able to see what the data-enable signal does with your oszi.

0,05us (50ns) sounds much faster that I would expect for software driven. I'll scope the CD371/472 when I get time.

I hope this clarifies a little.

Gyro

[mickeyratt]

Dear Gyro and anybody who can help.

I get a vintage Philips CD371 CD player, which works perfectly, except the display.

All LEDs, and display is dark. I think, it is a NSM4202 error, because the serial lines from MCU to NSM works, as i see on oscilloscope.

I'd like to save the original green 7 seg display to get maximum authentic look and feel
I tested the 7seg displays in NSM4202, and noticed that they are not multiplexed, this driver has 35 current limited driver - hmmmm.

Is there anybody, who succesfully implemented a microcontroller based solution to this problem? (the original NSM part has horrible prices )

I think to cut common anode wires, and short each digit (a-g) segments on NSM panel to get multiplexed driving with a PIC16F... .
Thank you in advance for any help, and sorry for my english!!

[dacen]

This chip has the same function as the NSM4202:
http://www.micrel.com/_PDF/mm5450.pdf

[mickeyratt]

Dear Dacen

Yes, it is, thanks for the tip.

I created a small website to describe a replacement solution to nsm... displays:
Restoration of NSM4202 NSM4002 displays founded in Philips CD Players | Vintage Audio

Thank You!