Electronics > Beginners
Naked ground plane PCB (what's the proper name)
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eb4fbz:

--- Quote from: 13hm13 on May 26, 2018, 09:10:34 pm ---
--- Quote from: eb4fbz on May 26, 2018, 03:51:23 pm ---Ground plane? Maybe you are confused because of the fact that metalized vias didn't exist in those days, so ground connections were done using wire jumpers.

--- End quote ---
There are SMDs on the other side of that PCB, so there are vias.

 The copper plane your see on the component side is (0v, common), and both digital and analog devices are common (grounded) to it.
Schematics for this 1988 device are here if anyone is curious:
https://www.hifiengine.com/manual_library/philips/cd473.shtml

BTW: The query remains unanswered: if this style of "naked ground plane" is not a ground plane, what's the proper name.

--- End quote ---

Using SMD components doesn't mean there are vias. There are no plated vias in that board, and ground connections to the ground plane are done using wire jumpers with a solder blob in the middle at the ground layer. Unplated holes are just holes, not vias, and IC ground pins are not directly soldered to the ground plane to reduce costs.
13hm13:

--- Quote from: eb4fbz on May 27, 2018, 09:50:05 am ---Using SMD components doesn't mean there are vias.
--- End quote ---
I never meant to imply that -- apologies for the confusion. However ...


--- Quote --- There are no plated vias in that board, and ground connections to the ground plane are done using wire jumpers with a solder blob in the middle at the ground layer. Unplated holes are just holes, not vias, and IC ground pins are not directly soldered to the ground plane to reduce costs.

--- End quote ---
If a wire (or "connector") goes thru a hole in the PCB, at strategic positions, to that Cu plane on the component side, isn't that a "vertical interconnect access" ... or just  a "jumper"?

BTW: a riddle for those playing along at home:
That whole (stuffed) Philips board may contain MANY, MANY vias of the kind everyone can agree upon. Where are they?
Gyro:
No, sorry. The definition in of a via in a PCB is very clear, a via is a part of the PCB itself. The creation of vias is part of the bare PCB manufacturing process.

Every connection on that board is either a component leg or a wire, inserted through a non-plated hole or a surface mounted part. No vias, no riddle....


--- Quote from: 13hm13 on May 27, 2018, 12:58:10 am ---...
Wiki notes:
"In printed circuit board design, a via consists of two pads in corresponding positions on different layers of the board, that are electrically connected by a hole through the board. The hole is made conductive by electroplating, or is lined with a tube or a rivet."
...

--- End quote ---
13hm13:

--- Quote from: Gyro on May 27, 2018, 09:14:07 am ---
The ground and therefore supply noise is particularly bad around the SAA7220 digital filter, leading to its bad reputation and many conversions to 'non-OS' - you can see a badly implemented one in one of your photos (the overlong black wires).

--- End quote ---
Personally, even with the stock Philips player, I prefer the oversampled sound over NOS.
There are several other issues with the 7220 that de-optimize its performance. One main one:  it being used as a clock divider (divider by 2, for the good of the downstream TDA1541 dac). But, also: the clock signal to the upstream decoder (SAA7210) being routed thru the noisy 7220.
The SAA7220 is a pretty good digital filter if implemented right. Many high-end audio companies (esp in UK: Creek, Naim, Arcam), continued to use it (with its partner TDA1541), in various CDP models,  almost into the new millennium.
13hm13:

--- Quote from: Gyro on May 27, 2018, 04:21:26 pm ---Every connection on that board is either a component leg or a wire, inserted through a non-plated hole or a surface mounted part. No vias, no riddle.

--- End quote ---
Re-read the riddle .. .and try again  ;)
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