log 006

learning the ropes…

soldering, connectors, cables and shielding

Once I opened up the cassette deck it was like entering a world of nesting dolls. Trying to get a grip of the situation I once again had put myself in to (total confusion that is) I started making lists of the most obvious things to learn. Soldering was first out since I had to custom make a few cables to test if the first theory of how to hack a sound output from Deck B would work out or not. It didn’t. From what I could see the rotating tape head is wired electronically due to the play function called play mode. Sony TC-WE475 has only one tape head per cassette unit wich means it plays, records and deletes all by the same head. It also means that all of the instructions and hacks I’d seen was not applicable. That was a good explanation as any as why I haven’t seen any hacks made with electronic audio equipment from the 1990s.

Pinhead connectors

By looking and learning from youtube channels it made sense to try and find something inside the deck that was kind of similar to the older electronics they were hacking, building, fixing, cleaning, testing or whatever the purpose of the video was. I just have to mention this because youtube has been a vita source of information for me during this last year as a total noob. The pin connection on the pic below, was the most similar thing I could find. At least it would (hopefully) have same function as if it was connected straight to the tape head itself, but in this case via the pinhead on to a small pcb then wired electronically the last bit. There’s no standard of how pinhead connectors are distributed but thanks to the schematics in the service manual it was possible to understand the wiring.

 

 

 

 

 

schematics crash course

I think of the Sony TC-WE475 as analog-digital hybrid. The ‘trial and error’ method I usually go for when learning about stuff in theory and practise was no longer useful. I learned this by experimenting with another deck of the same model and kind of destroyed it altogether. So I needed to gain knowledge in another way to get the result I wanted. To do this the following steps were taken:

 – Get the service manual

– Find an engineer to get a crash course in how to read schematics

– Study the schematics over and over until understanding the signal flow

 

 

 

 

 

The idea (see log 001) was based on using each cassette unit (2 per deck) autonomus using it’s own motor spinning the tape loop through each unit. It could be presented in a  railroad model setting, but tape being the railroad. It is doable but it is also making it very hard for oneself.

Unfortunately my prior ideas of how to get the units out of the box was useless if I wanted to keep the play, rec, stop and dub mode intact. The problem was the extensive use of eletronic wiring. I learned that the all of the advanced functions they crammed in the deck; rotating tape heads, auto reverse, and recording your own program etc depended on electronics. In the Sony TC-WE475 model everything from the frontpanel and the cassette unit is wired back to a center at the bottom of the mainboard via an FFC. That means; to even get the sound out properly (not taking the signal straight from the pre amp) I had to have the FFC connected between the mainboard and  the frontpanel

FFC

  • FFC = Flat Flexi Cable
  • FFC is a miniaturized form of ribbon cable, which is also flat and flexible
  • Pitch. Avståndet beräknas mellan pins på kabeln (0.5mm, 0.625mm, 0.635mm, 0.8mm, 1.0mm, 1.25mm, 1.27mm, 2.0mm, 2.54mm)
  • Pins. For some reason the Pin number on Sonys customised FFC in the TC-WE475 model does not exist anywhere else on the market
  • Most common cable length: 10-20cm
  • Type A: stripped and reinforced on equal side
    Type B: stripped on both sides, reinforced on one
    side
    (except grid 0.50 mm)
    Type C: stripped on both sides, no reinforcement
    (except grid 0.50 mm)
    Type D: stripped and reinforced on opposite sides

 

 

The next step was to find a way to make a FFC extension. Any board-to-board connector was out of the question. I was looking for a kind of wire-to-wire  pin header and as it turned out it does exist for ribbon cable but not for FFC. This was a crucial discovery since Not knowing better, I assumed this would not be a problem. In a moment of despair I tried to make my own extension by solder a ribbon cable on to the FFC but in the end it was too difficult for me.

Well, as I was saying; In the end, I didn’t find a solution on the extension problem. After all, since the dawn of electronics it seems one of (if not the) the main focus  has been to make components smaller. Problem is; it’s not a sustainable way of thinking. Well, that is of course if you care about recycling and sustainability or not. (Links at the end of the post for further reading).

I’d just like to throw in my gratitude and many thanks to a private seller of FFC’s at  Ebay that helped me identify what kind of FFC I was dealing with.

 

 

 

 

 

 

 

 

 

further reading:

history of compact cassettes

A post from Open Electronics on PCB recycling

An article  from ScienceDirect about Resuse and recycling of electronic components

 

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