PCB Repair Logs – Page 30

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

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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 so I made a very rough replacement that worked fine:

Later I properly reproduced it :

Another PCB fixed and another (little) custom reproduced.

Gals Panic repair log and Kaneko ‘PX4460’ – ‘LPF6K’ reproduction

PCB Repair Logs, Reproductions 1 Response »

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.

Vanguard repair log

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Feb 242018

Bought this classic as not tested but luckily it was working except the missile sound was completely missing.

Looking at the schematics I found this

In the game there are only two missile sounds.

Shot A is your ship missile sound, while Shot B is the one from some enemies

IC37 is an LM3900 op amp which is very unreliable and infact after changing it , the missile sound was restored

Labyrinth Runner repair log

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Feb 242018

The game was working good except the sprites were all missing some lines

The board is using some unreliable drams 41464 from Fujitsu similar to the ones used on Konami Haunted Castle or CPS1 A board.

I bought some units from Aliexpress , put some handmade socktes and changed both to be 100% sure

Turned out only one of the two was faulty, in anycase the graphics were 100% fixed

Joust repair log

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Feb 242018

I bought a Joust boardset declared 100% working.

When I tested it all the coin inputs didn’t work

I ran the test and infact they were all activated

I was not worried because I was sure it was the 6821P PIA on the romboard.

After replacing it didn’t fix the problem.

Looking at the schematic there are also some 4066 CMOS chips involved.

I desoldered the one used by the three coins inputs and after testing it on my programmer it was declared good.

I decided to add a socket and test another one on board

Luckily the problem was fixed and it turns out my programmer is not reliable in testing CMOS devices.

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