Tokugawa Corporate Forums

Retro Japanese Computing
It is currently March 28th, 2024, 12:13 pm

All times are UTC




Post new topic Reply to topic  [ 4 posts ] 
Author Message
PostPosted: March 20th, 2012, 7:13 am 
Offline

Joined: January 3rd, 2012, 7:22 pm
Posts: 24
Location: Vancouver, British Columbia, Canada
I've figured out that it might be possible to rebuild the cassette interface of the FM-77AV40SX. Cassette software makes up a large part of the FM-7x software library, and that part is completely cut off from owners of the FM-77AV40SX. I have discovered that it may indeed be possible to rebuild the cassette interface. The solder points are indeed there on the FM-77AV40SX motherboard, but they are unpopulated. I have gone through with a continuity tester and the schematics of the original FM-77AV, and I have constructed a plan to rebuild the interface. There is only one problem. The central part to the whole deal is an ASIC from Fujitsu that is next to impossible to lay your hands on. I have managed to get 5 of them from a supplier in China, and there are 6 more available from the same source, but they are used, probably reclaimed from scrapped FM-7x series machines, and after these 11 are gone, I don't know if it will be possible to get more. I am going to try and get a friend of mine to reverse engineer one, it shouldn't be too hard. I will hook up a logic analyzer to the leads of the chip and then load and save some cassette software and see what it does. In the meantime, here is what is required if anyone else wants to give this a try as well. Keep in mind these directions are untested and there is no guarantee they will work. I will test them on Thursday and let you know.

Parts list:
Capacitors: 3300pF, 0.015µF, 0.022µF, 0.068µF, 0.1µF Ceramic capacitors
Resistor: 560Ω - I am not sure of the wattage required, I took 1 watt to be safe
Relay: HRS1H-5V This is the only part I have found that is the right size. All the relays I've checked out that have the proper pinout are too small.
MiniDIN connector: MD-50S 5 pin female MiniDIN
ASIC: Fujitsu MB43413 DIP14
OPTIONAL: 14 Pin machine pin DIP socket .3" row spacing, maybe get two and use one as a relay socket.

Directions:
It is a very straightforward procedure. Looking at the computer from the front and above, all the components go in rear right corner. Just put the parts into the spots that are labeled for them, installing the capacitors in the following locations:

SX Value (F)
C13 0.022µ
C35 0.1µ
C36 0.068µ
C37 0.015µ
C38 3300p

Put the resistor into the empty place marked for a resistor next to the relay, I will update this post with the exact location shortly, I need to double-check the motherboard. Put the ASIC in the spot labeled MB43413. The metal frame of the case has a hole in it for the cassette MiniDIN connector, but the backplate does not, so make a hole in the backplate, and you are done. I will let everyone know on Thursday if everything works out. Also, the final firmware for the PS/2 keyboard adapter will be done any day now. Let me know if anyone else tries this!


Top
 Profile  
 
PostPosted: March 20th, 2012, 11:00 am 
Offline
User avatar

Joined: May 15th, 2010, 1:35 am
Posts: 701
I don't own an FM-7 series, but I just wanted to say how awesome this is. :)
Good luck - I hope the project succeeds.


Top
 Profile  
 
PostPosted: March 23rd, 2012, 4:43 pm 
Offline

Joined: January 3rd, 2012, 7:22 pm
Posts: 24
Location: Vancouver, British Columbia, Canada
It works! Well, I can't say that for 100% yet, because I haven't constructed the cassette cable, but I can say 99% that it works, since when you type load at the basic prompt, the relay clicks on and "Searching" is printed at the basic prompt. Another step forward for the FM-77AV40SX! More to come as it develops. Also, as a side note, I have a Sharp X1 TurboZ and a Fujitsu FM-TOWNS II UR on their way from Japan right now, thanks to my awesome friend Hasu! With luck I will also win the auction for the best cassette data recorder ever made as well!


Top
 Profile  
 
PostPosted: March 23rd, 2012, 4:54 pm 
Offline
User avatar

Joined: May 16th, 2007, 7:08 pm
Posts: 861
kobushi wrote:
I don't own an FM-7 series, but I just wanted to say how awesome this is. :)
Good luck - I hope the project succeeds.


Me neither, but yeah good luck with your project and the auction!

BTW, nice electronic skills! I'm looking forward to see the FM7 ASIC reverse-engineered, I'm curious about it, since it is not a critical component it should be fairly simple to reproduce.. maybe even with a PIC or akin.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group