The Philips CD100/00 I am working on has a factory mod - an extra PCB connected between the Demod and ERCO ICs - involving cut tracks in some of the data lines on the PCB.
As far as I can see this is undocumented in the (Dutch) service manual I am using, other than a tantalising mention in section 11.4 (second table) of a 'Demod Erco Interface Board', which it seems was fitted from versions A02 to A05 of the Demod board. I have drawn this extra board by inspection (see attached).
1) Can anyone please confirm this is indeed the 'Demod Erco Interface Board' referred to in the manual?
2) Can anyone confirm what its purpose was? (I've said what I think, on the diagram).
3) The table in 11.4 states that the Interface was added for use with a 'new' Erco IC M4281 and removed later for another 'new' Erco IC M4282. But this raises some further issues:
a) The Erco IC for all versions - whether before or after these changes - has the same Philips 12NC (4822 209 10377 - see parts lists). That suggests against there being different versions.
b) I have two ERCO ICs here, neither of which bear a number like M428x. Both have SAA7020, but the original then says 4108 and G8314M1Y and the proposed replacement says 3045 and rSG8631M2. These look like manufacturing codes. Can anyone tell me how to determine their M428x codes?
The issue is that the info in11.4 implies that some Erco ICs need this extra interface and some don't. How can a person tell whether or not to remove the interface when changing the ERCO IC?
Fitting and removing this board unnecessarily looks like it's best avoided, as many modified connections are involved. In short, it's a bodge.
As far as I can see this is undocumented in the (Dutch) service manual I am using, other than a tantalising mention in section 11.4 (second table) of a 'Demod Erco Interface Board', which it seems was fitted from versions A02 to A05 of the Demod board. I have drawn this extra board by inspection (see attached).
1) Can anyone please confirm this is indeed the 'Demod Erco Interface Board' referred to in the manual?
2) Can anyone confirm what its purpose was? (I've said what I think, on the diagram).
3) The table in 11.4 states that the Interface was added for use with a 'new' Erco IC M4281 and removed later for another 'new' Erco IC M4282. But this raises some further issues:
a) The Erco IC for all versions - whether before or after these changes - has the same Philips 12NC (4822 209 10377 - see parts lists). That suggests against there being different versions.
b) I have two ERCO ICs here, neither of which bear a number like M428x. Both have SAA7020, but the original then says 4108 and G8314M1Y and the proposed replacement says 3045 and rSG8631M2. These look like manufacturing codes. Can anyone tell me how to determine their M428x codes?
The issue is that the info in11.4 implies that some Erco ICs need this extra interface and some don't. How can a person tell whether or not to remove the interface when changing the ERCO IC?
Fitting and removing this board unnecessarily looks like it's best avoided, as many modified connections are involved. In short, it's a bodge.
How to attach an image or file. If the file is to large (check the size limits allowed on the 'manage attachments' window then see if it will fit in a zipped folder (max 976kb size)
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
Missing diagram attached
Thanks Mooly,
So here I am re-trying to upload the attachment referred to in my previous post.
Thanks Mooly,
So here I am re-trying to upload the attachment referred to in my previous post.
Correction to diagram
Pin 13 of the 74LS86 is connected to pin 14, not pin 12 as shown. Apologies for this error.
The 74LS86 outputs two pulses for every cycle of the CLOX input, but it isn't obvious (to me anyway) why this was needed.
Pin 13 of the 74LS86 is connected to pin 14, not pin 12 as shown. Apologies for this error.
The 74LS86 outputs two pulses for every cycle of the CLOX input, but it isn't obvious (to me anyway) why this was needed.
The Erco IC is SAA7020.
Specifically, the original in the machine is labelled:
SAA7020 4108 G8314M1Y
However, I obtained another, labelled:
SAA7020 3045 rSG8631M2
either of these works OK with the extra board, but I've tried neither without it because the machine is now working. ('If it ain't broke don't fix it!')
(In my case the ERCO IC was OK but the Demod IC was blown. The original of that was labelled M4290A, but I replaced it with one labelled SA7010 (as per service manual). I think this was a slightly different (later) IC, because I had to add R3531 (270K) to make it work reliably - as per Philips update A07 in section 11.4 of the manual. However, the interface board is still in it and working. The only remaining symptom is that the machine doesn't always PLAY after initial switch-on, but switching it off and on again clears it.)
Specifically, the original in the machine is labelled:
SAA7020 4108 G8314M1Y
However, I obtained another, labelled:
SAA7020 3045 rSG8631M2
either of these works OK with the extra board, but I've tried neither without it because the machine is now working. ('If it ain't broke don't fix it!')
(In my case the ERCO IC was OK but the Demod IC was blown. The original of that was labelled M4290A, but I replaced it with one labelled SA7010 (as per service manual). I think this was a slightly different (later) IC, because I had to add R3531 (270K) to make it work reliably - as per Philips update A07 in section 11.4 of the manual. However, the interface board is still in it and working. The only remaining symptom is that the machine doesn't always PLAY after initial switch-on, but switching it off and on again clears it.)
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