Enhanced Gotek: The Brutek!

Brutek PCB imageFor a long time, I have worked on recreating the Gotek and in the process adding extra features and several bugfixes from the original Gotek. v1.0 was just a prototype replica of the original Gotek with some of the pinheaders moved for easier flashing. I just wanted to see if I could get one to work. Summer 2019, I gifted v1.0 to everyone that showed up to a local Amiga game night and requested they would perform extensive testing. They all still work, but they had some design flaws like the screw holes was not at the correct location, regulator needed more cooling area, the PCB was about 4mm too short, the tactile switches was placed too close. So I modified my “Bruktmoped” Amiga 500 internal frame to fit the replica with wrong screwhole placement, so my testers could place the prototype internally to their A500 machines.
v1.1 had these issues rectified and I decided to implement the mods that the awesome FlashFloppy firmware supports, plus some things I wanted changed myself, including more SMT friendly layout compared to v1.0.

These are the things I have changed/added:

  • Added a power LED
  • Removed R10
  • Moved and added pinholes for more jumperfriendly layout.
  • Replaced the cheap electrolytics with SMD capacitors. (from v1.2 and up)
  • Used genuine ARM® Cortex®-M3 processor. (instead of those fake ones often found on Goteks from China.
  • Replaced STM32 output buffer with more suitable chip for that application. (From 74HC04 to 74HCT04)
  • Added 3pcs SMD LEDs (from v1.2 and up)
  • Replaced R13 with higher value resistor for more stable programming. (From v1.2 and up)
  • Added pulldown resistor to Boot1.
  • Made holes for optional header to pullup Boot1 with a jumper.
  • Board identifier set to support Enhanced Gotek mode with FlashFloppy.
  • Added support for the upcoming FlashFloppy feature “Second drive support” (PA3 pulled up.)
  • Added jumper friendly pinholes for the upcoming FlashFloppy feature “Second drive support”
  • Added LED for the upcoming FlashFloppy feature “Second drive support”
  • Added motor ON feature. (For future FlashFloppy features)
  • Holes to connect Rotary encoder, with extra pin for drive eject/insert
  • Onboard speaker holes for passive buzzer. (for drive sound emulation)
  • Transistor circuit so even 5V active buzzer or magnetic speaker can be used, and higher volume is possible.
  • Added pullups to SCL and SDA so there is no need for modification when using a two- or four-row LCD with I2C backpack board
    instead of the usual 7-segment original Gotek type display, or a OLED screen. (From v1.0 and up)
  • Added pullups to several floating datalines.
  • Moved and changed Crystal to high accuracy SMD version. (from v1.2 and up)
  • Made fiducials for factory SMT option.
  • Changed values on several passives.
  • Did a google for other enhanced Goteks, and borrowed some great component placement ideas from other
    PCB designers smarter than me! (from v1.2 and up)
  • Correct pullups for SCL and SDA so the 4.7k resistors mentioned in flashfloppy OSD guide is already in place.

Soldering

Every now and then, I come across someone that tells me they can’t solder electronics. But the good news it, chances are that not only can you solder, but you can solder well too.

If you tried and failed, you probably did not have the right equipment for the job. Soldering is much easier than you probably thought. But for it to be successful, you need the correct tools. You can even go for the cheapest Chinese options and be successful.

The first obstacle is usually a wrong soldering iron with a tip that is probably corroded and the wrong size. Many people uses soldering irons made for plumbing or heavy duty soldering. Its a given that expensive tools from professional equipment manufacturers will be the best option if you can afford them. But thats not for the average beginner. This is what I recommend for the cheapest option:

  • A soldering station with adjustable temperature, and interchangeable tip.
  • An assortment of tips for the soldering iron
  • A brass tip cleaner
  • Decent quality thin solder wire,  I use 0.5mm for through-hole components and 0.3mm or solder paste for SMD

A lot of experts might laugh, but Ive used a cheap Chinese soldering station for years now, since I no longer have access to the high priced units at work anymore. I use it almost every day, and dont really care that its of lower quality than expensive ones.

What I would do, is to look for the latest Hakko clone there is, on eBay, Aliexpress or Amazon with search words like this: Soldering Station 852D, 936, 937D, 898D, 937D, and look for a soldering station that have a heat gun if you want to solder SMD, or at least a replaceable soldering iron with a 5pin banjo connector. The base station should work for years, but the iron itself will sooner or later need replacement. If you choose one that uses a 5pin banjo connector, replacements can be found for as little as $3-$5, and replacement tips can be had for $4-$5 for an assortment of 17pcs. Get one or two replacement irons for your drawer. But of course, if you got the money to spend, go for a Hakko and never look back. The solder wire on the other hand, will be where you put your money. No cheap Chinese stuff will do.

 

Playing with stencils

Using a solder paste stencil is a quick way to get your production speed up when dealing with SMD parts (surface mount devices). At my house, its done because its fun and messy. But what exactly are they? A solder paste stencil is a metal or polymer plate with holes in it that represent the solder pads on your PCB.

This is a stencil for my Vehicle Charge Indicator. It can apply solder paste on 60 units at once.

All you have to do is to apply solder paste all over your stencil, remove it, and now a thin even layer of solder paste covers all your solder pads. Solder paste is liquid solder, often provided in a can or inside a syringe.

My preferred method is to place the target PCB in the middle of a wooden plate, align the stencil on top at the perfect spot, and later secure the target PCB with older PCS’s in all corners to keep it in place. Lastly, I have to secure the stencil in one corner perfectly aligned with the target PCB. If done correctly, I can now carefully replace the target as many times as I want, and flip the stencil over for a perfect fit with no hassle. I store it in a cardboard box for next time.

Old PCBs are used to keep the target PCB in place. To the left is the metal stencil ready to be folded over the target PCB.

Vehicle Charge Indicator

Not every vehicle is equipped with equipment that tells you that the charging system is not working. That is certainly true for several of my vehicles. So decided to think of a way to monitor the charging system, but since I do not want some kind of big, expensive, ugly device for this, I decided that I should just make a simple solution with a LED and some kind of small circuit board. So I came up with this.

DSCF0718

Look how small it is! 10pcs PCBs ready for a LED in one end and a Power cable on the other. The green and red LEDs are 3mm, and the blue and yellow are 5mm. The bigger ones are 8mm and 10mm, and gets more visible, but require a bigger mounting hole.

This can be used on Cars, Motorcycles, Mopeds, ATVs, Boats, Tractors, Snowmobiles, Snowblowers, Lawn mowers etc. anything that have a charging system. 6v, 12v and 24v versions can be made from the same PCB.

Its simple. If the alternator is charging, the LED lights up. No light, no charge. The design is made so that you can connect it directly on the battery or on the output from your rectifier, and it will not drain any power while the vehicle is not in use. There is no fuse, so you might want to add one to the wire. The circuit can handle reverse voltage for a while, but sooner or later the diode will break down, so try to connect positive to positive and negative to negative.

The idea is that with only a small hole somewhere suitable on the vehicle, one could drill a hole for one LED, ranging from 3mm to 10mm depending on available room and personal preference. I wanted the device to be as small as possible, so I went with SMD parts, to save space. Just for fun, Im gonna try to post this device on ebay, but if you rather want to make your own, I will let you know how it works, and list the parts you need.

charge-indicator

Partlist:
D1: 12v Zener Diode
R1: 56 Ohm Resistor
D2: 1N4007 Diode
L1: LED
LED holder
Shrink tube

The theory is this:

We don’t want the LED to power on unless the vehicle is charging. So the power from the battery will be blocked by the Zener Diode (D1). But when charging is taking place, the voltage to the battery will be a raised from around 12v to around 14v. A normal charge would be from 13.7v to 14.7v. If you get less or more than that, you need to check your regulator. When the Zener diode (D1) reach the breakdown voltage generated by the charging system, power will pass through, and make the LED (L1) turn on. The resistor (R1) is there to protect the LED (L1). The resistor value can be changed according to how bright you want the LED to shine. D2 is there to protect from reverse voltage generated by the alternator.

For a 6v charging system, all you need to do is to replace D1 with a 6V Zener Diode.
For a 24v charging system, all you need to do is to replace D1 with a 24V Zener Diode.

This project with PCB and parts can be purchased on ebay:  https://www.ebay.com/usr/kirsti_73

Minipro TL866 27c400/800/160 Adapter

I really love my MiniPRO TL866 programmer. It has so many supported chips. I save a lot of money not having to buy several programmers for my hobby.

DSCF9362

But unfortunately it does not support 27c400/800/160 eeproms. When restoring Arcade games, I some times come across those ROMS. A common fault for old ROMS is that the programming some times become corrupt. Then you need to re-program them using a programmer like this. But since my programmer wont support these chips, I decided to manufacture a solution of my own.

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The main reason some of the chips wont ever be supported by the TL866, is that the programmer has only a 40 pin programming socket. So the adapter needs to work around this. In this design, this is done by selecting the AMD 27C4096 in the programmers software, deselect “Check ID” and program the chip in several runs of 512kB , so you have to split the file into sections of 512kB to match the size of a 27C4096. The jumpers A18 and A19 on the top is used to select each bank to program. It works like this:

  • To program the 27c400, no jumpers required, since it is already 512kB. So no need to split the file.
  • To program the 27c800 which is 1024k, start with both jumpers at zero (lower 2 pins) for the first 512kB, then set J18 (top 2 pins) for the second round of 512kB .

To program the 27c160 which is 2048k. This file has to be split into 4 sections of 512kB. The first part with both jumpers set to zero, the second with J18 set, the third with only J19 set, and the last with both J18 and J19 set.

  • DSCF9360.JPG

Picture shows me getting ready to program Kickstart 3.1 for my Amiga 500. If you are going to program 27c400 kickstart chips for the Amiga, leave both jumpers at zero.

How to program a 27c400 120ns eprom with the TL866 to make a Kickstart chip:

Im gonna use Diagrom as an example.

  • In MiniPRO software, select AM27C4096 DIP-40 under device.
  • Uncheck “check ID” in the lower part of the screen.
  • Verify that the EPROM is blank. Select Device – Blank Check.
  • No jumpers should be set at J18 and J19
  • If you havent already done so, download newest version here: http://www.diagrom.com
  • Select File and Open and browse to the location where you downloaded Diagrom
  • File is already byteswapped, so select Device and program. Wait til its finished.
  • If you run into problems, try adjusting the VPP Voltage between 12.5 and 13.5.
  • Some models need 2 ROMS (32bit) on those models you need to program each chip with their correct file, like 32bitHI.bin and 32bitLO.bin.

You should supplement your programmer with a UV eraser. The cheap ebay ones work for me.

This project with PCB and parts can be purchased on ebay:  https://www.ebay.com/usr/kirsti_73
or from Sellmyretro.com

Diagrom is a great tool for diagnosing you Amiga computer.

You can buy legal Kickstart files at http://hyperion-entertainment.biz

You can download Diagrom for free at http://www.diagrom.com