JAMMArcade.net – Page 49

Backing up an old BBC Micro cassette tape

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Feb 252018

My friend was wanting to backup an old BBC Micro cassette tape that he believed had a game on it his grandad had made. The tape was marked up as “The Wizards Mountain”

I’d never backed up a cassette tape before and I didn’t even own a tape player anymore.
I originally tried buying a really cheap and nasty portable tape player

This was a total disaster and I kept getting inconsistent reads on various parts but between several reads I had what looked like a complete good read.
Using the ‘BBCTAPEDISC’ program I was able read the data directly from the ‘line-in’ source and it also gave a live update on each block recovered so I could see what was failing.

I originally tried stitching different parts together to make a good file but I just couldn’t get it to work properly so I asked around to see if I could borrow a better tape player. Fairly quickly I ended up with this

This gave me an almost perfect read first time. I ended up with a disc image instead of a tape image but thats fine with me as it loads faster.
The outcome is a text adventure game that appears to have been made with GAC.

Its actually a nice story which I still need to finish once I get some time but we are both really happy to have this saved.

Vanguard repair log

PCB Repair Logs Comments Off

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

PCB Repair Logs Comments Off

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.

Nastar repair log

PCB Repair Logs Comments Off

Feb 232018

Found this Nastar (on Taito B System hardware) in a lot of faulty PCBs I recently bought:

Board played fine but sound was terribly loud and corrupted :

I fired up my audio probe and started “listening” to various points of the sound circuit.Hardware uses an YM3016 DAC (SOP package, always used in conjunction with the YM2610 sound synthesis IC)

As you can see from the above pinout, its pin 13 (TO BUFF) is the analog output that goes to the pre-amplification circuit (two TL074 OP-AMPs used on this board).”Listening” to this pin confirmed me that sound came out bad from the DAC :

I took a spare from a Football Champ donor board:

Installing it restored a crystal clear sound.End of job.

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