ABI Junior

[cliff_poole]

This morning's radio rally find !.




I haven't Googled it yet, but does anyone know if there is a manual available, or anything else useful ?.

It appears to only go up to 24pin devices from what I can tell on the menu and it's a shame it doesn't have the out of circuit ZIF socket, but at least it came with cables and does pass it's self test.

 

[Ace`]

Wow that's cool never even knew they existed. Looks like it's going to work pretty much the same as a Boardmaster 4000 minus the out of circuit testing and the LCD. Remove / disable the crystal, attach the clip to the chip you want to test and the black croc clip to ground, type in the part number and away you go.

Does it have a floppy disk drive on the side?

 

[Retroman839]

Nice.

 

[cliff_poole]

No floppy or keyboard input, but on the plus side, it is relatively small and light which will be good with my limited desk space. Unfortunately the menu system isn't that easy to figure out, not helped by the keypad being a bit temperamental. There is a monitor socket that I will probably probe with the scope to work out the pinout. Could be a bit easier to use with that attached.

 

[Ace`]

It'll require a MDA monitor, the pinout is on my blogspot. There was a pc LCD monitor you could get that supported MDA but prices have gone up quite a bit because people use them for amigas and other stuff.

The keys get better over time the more you use them.

 

[cliff_poole]

Now that I have had a bit of a play, the menus are easier to use than I first thought. Standard 2x16 character display, chip information scrolls along the bottom row.

Can anyone tell me how to orientate the test clip please ?. I have left the clip connected as it was when I got it. There is power to the chip and I have the ground ground clip connected to ground (blue wires). Just testing on breadboard for the moment. The errors are either No VCC or No GND.

Here is how it is connected at the moment.



Thanks.

 

[Macro]

Where is the chip getting power from? You should power the PCB/chip from the abi

 

[Ace`]

I personally never use the power supply built into the ABI and just use the switcher in my supergun. You don't have to worry about chip orientation but I don't know if the cables will work connected like that.

I've never tried but just for neatness if nothing else going from your second picture take off the bottom ribbon connector and put the test clip in the first pin of the top row (outter row pins top and bottom are all ground).

 

[Macro]

I personally never use the power supply built into the ABI and just use the switcher in my supergun.

Never tried that, worth knowing for the big PCBs that pull mega power

 

[cliff_poole]

Thanks very much, I'll try that.

I was using my bench supply to power the breadboard as there is no PSU output on the Junior.

What is the BDO cable for ?, It is in my first picture.

 

[cliff_poole]

Ignore my last question, I just found it in the Boardmaster manual.

 

[cliff_poole]

Thanks to everyone for the helpful comments. I finally got around to trying the ABI method of fault finding this weekend.

The game was A.S.O. by SNK, a fairly decent vertical and horizontal shooter from 1985.

On power up, the screen would display a series of coloured vertical stripes, before stopping on one pattern (vertical on my horizontal test monitor). I could tell the the sync was off due to image distortion at the edges.
Looking at the sync output with a scope, it was inverted, positive going pulses. At this point, I also checked the CPU activity, which seemed to be executing code for a bit on startup before coming to a halt. The ROMs all ID'ed OK against MAME.

There is no circuit diagram available, so deciding I needed to see what was on the screen, I started to trace the sync back. I followed it through the interconnecting cables to the bottom board, before hitting this.



The picture only shows a section. My close up vision isn't what it once was so it quickly became very frustrating. Knowing this would be a logic fault, I decided it would be a good time to try the ABI.

 

[cliff_poole]

First, I desoldered one leg on each of the two crystals to stop the clocks. Found a 20 way test clip. Adjusted the 5V supply so it was at 5V on a logic chip. Connected the ground clip of the ABI, and tested every logic chip, marking each one with a pencil as I went.
The process took under two hours, it would probably have been quicker if I weren't restricted to the 2x16 character display, which scrolls to list the state of each pin on failure.
All the shift registers failed, but I figured the ABI must have difficulty testing these when some of the inputs are hard wired high or low, and they were unlikely to be part of the sync circuitry. The only other failure was a 74LS21 on the bottom board.
Soldering the crystals back, I looked at the two outputs of this chip on the scope, both were low. Next, I found a new 74LS21 and bent up the two output pins slightly so they wouldn't touch anything when piggybacked on the chip in circuit. The outputs of this chip had a 15khz signal, so I replaced the chip.

Starting back up, I could now see it run through the ROM based test, then coming to a stop at the screen showing all ROM and RAM OK. The test switch dipswitch was on !, which should have occured to me from the start. Anyway, it is now fully working.

In conclusion, I was able to fix a game without too much brainwork, although the process was a bit tedious. Luckily, A.S.O. didn't have any big custom chips and not too many logic chips.

 

[USEFI5961]

Where is the chip getting power from? You should power the PCB/chip from the abi

Hello dear friend:Sorry in boardmaster 4000 Steel I have problem in LCD lmg5160 I don't find and I don't find benq BL702A.do you have solution for me?
Thanks.