Introduction

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hlide
Posts: 461
Joined: Thu Jan 25, 2018 9:31 pm

Re: Introduction

Post by hlide » Mon Aug 03, 2020 2:56 pm

I moved the overclocking discussion into a new topic: viewtopic.php?f=3&t=456

arnuphis
Posts: 10
Joined: Fri Jul 31, 2020 4:18 pm

Re: Introduction

Post by arnuphis » Thu Aug 06, 2020 6:29 pm

Thanks for the kind welcome. I replaced all the caps on the PSU. Now looking at the tape drive. Rewind works but Play and FF don't. It's like something is stuck as it tries then the green read LED goes off after a couple of seconds. Took the back off and boy is that thing buried in there. Going to tackle it this weekend. Any tips on what to look for? Aside from the obvious gunk in the gears.

psmart
Posts: 48
Joined: Thu Nov 21, 2019 10:12 am
Location: Leeds
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Re: Introduction

Post by psmart » Thu Aug 06, 2020 10:04 pm

Good luck, best to strip it completely down and give everything a clean at the same time.

The screen is actually quite easy to get off. If you unplug all the cables that are coming down from the screen onto the motherboard, then looking from the back, at the left and right side are two brackets, towards the back you can access on each bracket a screw, take them out, turn on its side and undo the other two screws which come from the underside. Once the screen is off, it is easy-ish to dismantle.

For the tape drive, it is automatic, if it doesn't sense a signal it will go from Play to Stop or Rewind/FF. I would hazard a guess it is just gunk and perhaps the drive band has stretched. Not playing/FF sounds more like a drive belt though. Also i'm not sure one of those fake cassettes will work (the type for injecting audio into a car stereo) as it seems to sense loading on the drive cogs as well. My 80B was quite battered, from Germany (they were big on Sharp's in there days so always worth looking at Ebay Deutschland as some goodies do come up - some guys will say Germany only for delivery so wont appear on a generic search but most are willing to send to you - I mention this aka your disk drive controller requirement) and probably used as a door stop, a lot of effort to clean it up but it works well now, a 40 year old machine, amazing!

Good luck! Anything you come across I can reference with my machine just ask.

psmart
Posts: 48
Joined: Thu Nov 21, 2019 10:12 am
Location: Leeds
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Re: Introduction

Post by psmart » Thu Aug 06, 2020 10:10 pm

Just to add, check out the service manual for the MZ80B https://original.sharpmz.org/mz-80b/dow ... 80b_sm.pdf section 24, this gives fault finding instructions for the tape deck. Looking at the schematic it has a sensor to detect tape motion and a micro switch, do the drive cogs turn when you press Play/FF the stop or just dont turn, if the former, could be this sense circuit or the micro-switch.

arnuphis
Posts: 10
Joined: Fri Jul 31, 2020 4:18 pm

Re: Introduction

Post by arnuphis » Sun Aug 09, 2020 6:19 pm

Thanks for the help. I got the drive out. No gunk to speak of but I cleaned up everything. The main drive belt to the motor is there but its a bit "sloppy" so I ordered new belts to try. If that doesn't work then I guess its time to test voltages. One quick question. The belt for the tape counter.. where does that connect? I pulled the tape drive out via the back of the machine and it popped off before I could see where on the drive unit it connects. The exploded diagram doesn't really make it clear. I may end up having to dismantled and take off the front bezel as I cannot see a way to connect it back up from the rear.

psmart
Posts: 48
Joined: Thu Nov 21, 2019 10:12 am
Location: Leeds
Contact:

Re: Introduction

Post by psmart » Tue Aug 11, 2020 9:35 am

I will have to check later, I stripped it down completely about a a year ago but too long ago to remember!!! One of the things I keep planning to do, but never get around to it, buy belts for all the machines I have, all are still on original!! My MZ80A is fine reading and writing tapes it makes but hit and miss with manufactured ones! No such issues with the 80B so far. Did you source an exact belt or order one by length/profile?

arnuphis
Posts: 10
Joined: Fri Jul 31, 2020 4:18 pm

Re: Introduction

Post by arnuphis » Tue Aug 11, 2020 4:45 pm

Thanks! I ordered a bag of cassette player belts of various sizes. So hopeful that one of them is the right length!

ysblokje
Posts: 8
Joined: Fri Aug 14, 2020 8:06 am

Re: Introduction

Post by ysblokje » Wed Sep 02, 2020 7:44 pm

Since I just signed up, I might as well introduce myself too.

- Male (I see a pattern here)
- 1976 (I could be the youngest of us all ;) )
- the Netherlands

The first "computer" to enter our house in the 80s was a second hand atari 2600. Quickly followed by a second hand MZ-721.
They MZ was my introduction into programming as nobody else owned one except for some people at the local computer usergroup (I was the youngest there too darn it). Started with BASIC and wrote some programs of which I was very proud and lost all of it. The 721 was succeeded by a 821 which I didn't use all that much because my dad bought an Amstrad XT(?) soon after.
Being the dumbass I was back then when things started to break I threw almost everything out.

Around 2001 I picked up a 821 at a flea-market and let it simmer in storage for about 19 years and with this summer being what it is I finally decided to give the thing a much needed cleanup (I will post pictures, if people are interested).
This same summer I decided to look into emulators and z80 assembler and see if I can create some things , but boy is that graphics hardware funky to me. I started my .asm coding on x86 with good old VGA where a pixel is a byte like the gods intended!

Regards,
Ys

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mz-80a
Posts: 204
Joined: Thu Jan 25, 2018 10:46 am
Location: Devon, UK
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Re: Introduction

Post by mz-80a » Thu Sep 03, 2020 10:31 am

Welcome :)
MZ-80A Secrets
https://mz-80a.com/

Sharpworks (Sharp MZ homebrew)
http://mz-sharpworks.co.uk/

hlide
Posts: 461
Joined: Thu Jan 25, 2018 9:31 pm

Re: Introduction

Post by hlide » Fri Sep 04, 2020 12:25 pm

Sorry I mistakely rewrote ysblokje post but I was able to reinstitate his post (pfewwww!) through the browser history (thanks to its cache, I huess).
but boy is that graphics hardware funky to me. I started my .asm coding on x86 with good old VGA where a pixel is a byte like the gods intended!
You mean 320x200x8b (linear mode, 256 colors)? So I guess you never had to go with planar mode with SET/OR/AND/XOR operations? Yeah, that linear mode was a blessing when it comes.

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