Apr 172018
 

Have you ever encountered the following scenario on your beloved arcade PCBs?

Probably sometimes.The cracked component is silkscreened ‘051550’, maybe now the name tells you something :

It’s a custom IC in SIL package that can be found on countless boards manufactured by Konami (from mid 80s to late 90s).Here’s the pinout taken from a TMNT schematics:

As you can see, it performs two functions :

  • master /RESET generation for the whole system and watchdog timer
  • coin counters handling

In the below scan of the “naked” component  I have highlighted the part of circuit that handles the coin counters.The other part is the /RESET generation circuit which is built around a power supply monitor IC like the Fujitsu MB3773 :

You can read its datasheet here:

http://www.jammarcade.net/files/Datasheets/MB3773.pdf

In this project I took into account only the /RESET function since it’s the most important and vital, coin counters can be now considered obsolete hence I intentionally omitted the relevant circuit.Anyway,  for my repro I wanted to keep the dimensions of the original part:

 

Here’s final testing on a Lethal Enforcers PCB:

See you all to my next reproduction project!

 Posted by at 6:39 pm
Apr 162018
 

The ‘PC040DA’ is RGB DAC (Digital to Analog Converter) used on some Taito PCBs from mid 80s like Rastan, Operation Wolf, Tokio, LSA Squad.As other similar color DAC it comes in SIL package:

But,  as you can see from picture above, unlike the “big brother” ‘TC0070RGB’, you will always find three ‘PC040DA’ (one for each color) on a same PCB.Technically speaking the custom is a 5-bit DAC (6-bit actually but the least significant bit is tied to GROUND or VCC ) for a total of 15-bit of palette data received on their inputs.You can see its pinout in this snippet of Bubble Bobble schematics:

This custom has been already analized and successfully reproduced some years ago, you can read more about on this french forums :

https://www.gamoover.net/Forums/index.php?topic=27336.0

But I decided to do my own reproduction taking inspiration from some bootleg boards where the component has been re-engineered with a simpified circuit.The prototype on breadboard worked fine:

So I developed a proper PCB:

This is the final testing on a Rastan PCB where the reproduction has replaced the original part related to RED color channel:

See you all to my next reproduction project!

 Posted by at 7:53 pm
Mar 232018
 

They are little but not for this less important so for joke we will call them the “Little Fab Four”.They are four small custom components we often see on our beloved arcade PCBs, this post is about the reproductions I made of them.

 

  • Konami ‘007324’

This is a part we can find on Lethal Enforcers PCB (and maybe other but I never encountered it), as schematics show it’s used to interface data busses of the 63C09E main CPU and its program ROM:

Techically speaking it’s a simple resistor pack.Here’s its reproduction

Testing the repro on its own PCB:

 

 

 

  • Konami ‘005273/005273A’ – Taito ’48CR-1′ – Technos ‘TRJ-001’                  

I put these three together since they have the same function, design and SIL package.They are 10 pin resistors/capacitors array used for inputs.The bigger resistors (from 1K to 10K Ohm) are used as pull-up of the inputs from edge connector, the smaller ones  (10o-200 Ohm) to route the signal to the remaining inputs circuit (which could be simple logics or ASIC).Lastly the capacitors (ceramic, 100-300 nF) are for filtering possible disturbs.

Here are the repro and their installation:

 

Testing on different PCBs:

 

 

Good things come in small packages!

See you all to my next reproduction project.

 Posted by at 10:40 pm

Teenage Mutant Hero Turtles repair log #5 and Konami ‘007340’ reproduction

 PCB Repair Logs, Reproductions  Comments Off on Teenage Mutant Hero Turtles repair log #5 and Konami ‘007340’ reproduction
Mar 182018
 

Got in a trade this untested Teenage Mutant Hero Turtles  PCB:

At first test the board turned out to be faulty.Sprites were scrambled and some sound samples scratchy:

 

I launched a MASK ROM test which reported as bad all four 4Mbit devices storing sprites data:

Obviously the result didn’t mean the MASK ROMs were all bad, this was quite unlikely but for sure there was a problem in the sprites generation circuit.

Most of the circuit is condensed in two ASICs, the ‘051960’ which generates the address for the MASK ROMs and the ‘051937’ which reads their data:

Judging from type of fault, the ‘051960’ was generating wrong address, you can see its implementation in this snippet of schematics : 

Also scope analyzing confirmed my suspicions :

This lead me to remove and replace the ASIC:

This restored sprites so the IC was really bad (it’s not the first time, see my past repair log of Block Hole)

Now the sound issue.A quick visual inspection revealed that one of the two components marked ‘007340’ was cracked in two:

As schematics suggest the ‘007340’ is a resistor ladder (R2R) used to convert into analog the digital bits outputted from the ‘007232’ PCM controller:

 

 

Schematics show internal layout and resistors values so I made a very  rough replacement that worked fine:

Later I properly reproduced it :

Another PCB fixed and another (little) custom reproduced.

 

 Posted by at 11:28 pm
Mar 122018
 

Picked up recently this cheap untested Gals Panic PCB (MCU protected version)

When powered up I was greeted by this :

All inputs (including SERVICE one) are handled by a custom in SIL package marked ‘MC-8282’ (found also as ‘MC-1091’ in other boards from Kaneko) 

I’ve already discussed the topic in my past post about the reproduction of this custom:

Kaneko ‘MC-1091/MC-8282’ reproduction

Most likely the component was internally faulty so I replaced it with a repro of mine:

Finally the board booted into game but the sound was barely audible also at maximum volume level:

After a visual inspection I found that the component silkscreened ‘PX4460’ was missing from sound section:

Board uses also another little sound custom, the “LPF6K”, here is a picture from another board for better understanding:

Actually you can replace them by installing the parts they are internally made of directly on PCB (there is silkscreening for them) but I wanted to keep the all-in-one solution the so I decided to have a look inside them in order to reproduce both (although the ‘LPF6K’ was not missing on my board).I removed the coating and did an Hi-Res scan;

On the left on the above picture it’s the naked ‘PX4460’ which, like its name suggests, embeds all the parts (minus the 1000uF 16V electrolytic capacitor, this is on the PCB) needed by the typical application circuit of the ‘LA4460’ amplifier as datasheet shows :

On the right of the scan, it’s the ‘LPF6K’ that contains an LM324 OP-AMP  and all its required parts, its function is to pre-amplify the sound.

Given the simplicity of both customs it took few time to figure out schematics and route them to a replacement PCB.Here is the result:

Installed on PCB ready for the smoke test:

Success!Sound was restored and both repro worked fine as replacement.

 

 Posted by at 11:10 pm