Taito NinJawarriors Color RAM Error Help

[gamescollector]

Hi Guys unfortunatly recently i have a problem with my lovely original Taito Ninja Warriors pcb, when boot it in the center monitor show COLOR RAM ERROR. (not show in monitor Left or right)
checking online I saw that these Taito cards often suffer from Toshiba RAM failures specifically the TMM2063P 8kx8 SRAM DIP28









I understand that I will have to replace one or two rams. The important thing for me is to identify the faulty ram without starting to randomly unsolder the 6 rams. I hypothesized that the faulty rams could be the central ones if the layout of the 3 ram rgb zone monitors is linear.
Online I found some adapters to be able to socket the rams from component side, and obviously I have to use a tester (at the moment I have the TL866II plus) that I have to understand if it can test them.

Does anyone have experience testing RAM by directly soldering it to the PCB?



I ask for help from you repair gurus

thanks in advance

 

[xga]

Toshiba TMM2063 RAM IC's (especially the glossy ones) are a common failure point on boards from this era. If you have replacement 64Kb RAM IC's, you could try the piggyback method — placing a known working RAM IC on top of each of the six existing ones, one at a time, then powering on the board to see if there’s any change. Depending on how the faulty RAM IC has failed, you might get lucky and notice a difference when piggybacking a particular chip, helping to identify which one needs replacing.

If you need to source 64Kb RAM IC's, this page provides a good list of compatible options: https://www.citylan.it/index.php/SRAM_8k_x_8. Be sure to order the 300-mil wide version.

If you haven’t de-soldered IC's from PCB's before, I’d recommend practising on a board you don’t mind damaging first. The large ground planes on these types of boards can make IC removal particularly challenging for beginners. I would also fit a dual wipe socket for the IC.

I don't use the TL866II plus but I believe you will be able to test the TMM2063 RAM IC by selecting the RAM type as "6264".

 

[gamescollector]

I IC RAM Toshiba TMM2063 (in particolare quelli lucidi) sono un punto di guasto comune sulle schede di quest'epoca. Se hai IC RAM sostitutivi da 64 Kb, potresti provare il metodo piggyback, ovvero posizionare un IC RAM funzionante su ciascuno dei sei esistenti, uno alla volta, quindi accendere la scheda per vedere se c'è qualche cambiamento. A seconda di come si è guastato l'IC RAM difettoso, potresti essere fortunato e notare una differenza quando esegui il piggyback di un chip particolare, aiutando a identificare quale deve essere sostituito.

Se hai bisogno di procurarti IC RAM da 64 Kb, questa pagina fornisce un buon elenco di opzioni compatibili: https://www.citylan.it/index.php/SRAM_8k_x_8 . Assicurati di ordinare la versione da 300 mil di larghezza.

Se non hai mai dissaldato IC da PCB prima, ti consiglio di fare pratica su una scheda che non ti dispiace danneggiare prima. I grandi piani di massa su questi tipi di schede possono rendere la rimozione di IC particolarmente impegnativa per i principianti. Io monterei anche un socket a doppia pulizia per l'IC.

Non utilizzo il TL866II plus, ma credo che sarà possibile testare il circuito integrato RAM TMM2063 selezionando il tipo di RAM come "6264".

thank you for all your information and advice, for a few days I have been continuing to study the situation and I am moving towards testing the RAM in circuit with an Arduino Mega with IC TEST CLIP 28 pins. I wrote myself a simple program that should be able to test the complete functioning of the sram.

As soon as I get all the material I will start the first tests. I read that I could try to test the sram without starting the power supply of the board but just with the 5V of the arduino. based on your experience is this correct ?

I really hope to identify the faulty sram, subsequently I will unsolder it with hot air on the component side with a nozzle for dip28.
I have a fair amount of experience in desoldering so I hope not to encounter many difficulties.


Also Fujitsu MB8464 is compatible form factor ?

 

[xga]

I read that I could try to test the sram without starting the power supply of the board but just with the 5V of the arduino. based on your experience is this correct ?

That's not something I can easily answer, sorry. I use a logic analyser that analysers the selected IC whilst the board is being powered.

Also Fujitsu MB8464 is compatible form factor ?

Yes, Fuji MB8464's are a compatible replacement and listed on that page I linked to. Just make sure you get the narrow DIP 300-mil type as they come in four different package types.