AY-3 8910 adapter for Amstrad CPC, to STOP exploitation for AY-3 8912!

[ikonsgr]

Hi,

 I recently needed to purchase an AY-3 8912 sound generator chip for one of my cpc, and found out that prices gone INSANE, the cheapest i could find was ~25euros/piece!   So,i've decided to design an adapter, in order to use the MUCH,MUCH cheaper AY-3 8910 (you can find it for ~2euros/piece or even less, on ebay or aliexpress).
So, this is the adapter board:

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And here is the gerber files for anyone interested to build it.
Adapter dimensions is ~5,3cmX3cm so it should fit inside any Amstrad cpc.
Adapter provides a 10pin port, to access power supply+2nd I/O port of 8910, and an optional pull-up resistor network, if needed.
Mind also that adapter is currently untested, but if you happen to need an AY-3 8912 chip, you can try this alternative.
In any case, this might be the only feasible option in the future, if prices of AY-3 8912 continue to rise... 

[ikonsgr]

I revised the board to fit better on a cpc 6128 board. Gerber files updated too.

[TotO]

I suggest to swap VCC and GND in case you are using a DB9 ribon cable for the external GPIO, else the GND signal will be lost at pin-10. (sure, nothing wrong if the full pins are used by plugging something on the connector)

[ikonsgr]

I suggest to swap VCC and GND in case you are using a DB9 ribon cable for the external GPIO, else the GND signal will be lost at pin-10. (sure, nothing wrong if the full pins are used by plugging something on the connector)

Done! 

[TotO]

Nice! 

I have expected that you will avoid the extra via.

[ikonsgr]

Nice! 
I have expected that you will avoid the extra via.

Power traces are too wide to cross between pin holes, so using via was the only way... 

[TotO]

No worry, it is what I have expected.

[stulish]

Hi, i have a few questions as i recently replaced the membrane of my CPC6128 and still have issues so i thought i would try the AY chip next.

1. if you are not using port B can that be left blank?

2. I assume for this you remove the current AY-3-8912 IC and then connect between where the IC sat on the motherboard to eh relevant pin position on this PCB and then install the AY-3-8910 IC in this PCB??

3. are you having the PCB made and could i purchase 1, i did find one place that would make 5 and ship for $10.44, but at that price when you add the cost of the AY-3-8910 IC and connectors etc, it may be as well just getting the AY-3-8912 IC

Thanks

Stu

[stulish]

I just ordered 5 pcb's (the smallest quantity i could order) with delivery it cost me £8.33 and i have ordered 1 AY-3 8910 IC for £2.73. delivery is in 7-10 days so i will let you know.

so in total £1.66 for the PCB and £2.73 for the IC total cost is £4.40.

if anyone in the UK needs one of the spare PCB let me know.

Thanks

Stu

[TotO]

1. if you are not using port B can that be left blank?

Sure, but it is a shame to lose it.
I have suggested to be a R2R 8-bit DAC mixed with the AY audio.

[stulish]

one other thing what is the pull up resistor there for, also what part number would that be?

[TotO]

The pull-up is optional. It is a 2.2 kOhm 8+1 resistor network.

[TotO]

I have done that (untested) to be tested on a 464/664 last week. Probably VCC and GND on the schematic are not required (available through the socket), but it is a commodity to have the good board and schematic visual.

[stulish]

Hi all i just found:

Adapter PCB for AY-3-8912 sound chip to AY-3-8910

cost is $3 from a UK seller based in Nottingham, this doesn't have the second port etc

Regards

Stu

[TotO]

@stulish Sure, no second port... It is the invert of what you require on CPC.

[stulish]

So i have replaced the AY-3-8912 IC in my CPC6128 with one from a CPC464 (it wasn't easy un-solderig the IC's and then re soldering).

anyway the same fault remains with the CPC6128 so i now dont think the AY chip was to blame.

the errors i see on screen are different with the two membranes (old membrane and new replacement membrane).

I have updated a video of with each membrane fitted pressing each button on the keyboard in turn so you can see the difference, the new membrane has more keys not registering so i am thinking it is faulty and it was also delivered in a box where it was folded over quite badly (i would have expectd something to keep it flat.

the link for the videos are below:

This video is of the new membrane, at the end i show the old membrane and the poor repair attempt that had been made (this made me think the membrane needed replacing):

The video below is with the old membrane installed:

Let me know if you have any thoughts as to what to try next.

Thanks

[GUNHED]

Where to get such a new CPC6128 keyboard membrane today?

[stulish]

I got it from a company called SINTECH in Germany,  SINTECH Shop has these for 32.73 euro, however because i am in the UK they couldn't ship to the UK but i could buy from their ebay store (at more cost).  overall it cost me euro (48.77 + 4.39) 53.16 with delivery from eBay.

hopefully they will get back to me about either how to test or a replacement item.

I just put the 6128 AY-3-8912 IC into the CPC464 and the keyboard works fine on that so it wasn't the IC for me.

Regards

Stu

[stulish]

Where to get such a new CPC6128 keyboard membrane today?

I got it from a company called SINTECH in Germany,  SINTECH Shop has these for 32.73 euro, however because i am in the UK they couldn't ship to the UK but i could buy from their ebay store (at more cost).  overall it cost me euro (48.77 + 4.39) 53.16 with delivery from eBay.

hopefully they will get back to me about either how to test or a replacement item.

I just put the 6128 AY-3-8912 IC into the CPC464 and the keyboard works fine on that so it wasn't the IC for me.

Regards

Stu

[GUNHED]

WoW! Not cheap. But thanks for the info.
Hope you get your system running in the way you want. 

[eto]

WoW! Not cheap. But thanks for the info.
Hope you get your system running in the way you want. 

they produced a whole new batch for the 6128 and the Plus range. When thinking about that and that they need to make a profit, the price seems to be fair. 

[GUNHED]

.

[stulish]

WoW! Not cheap. But thanks for the info.
Hope you get your system running in the way you want. 

they produced a whole new batch for the 6128 and the Plus range. When thinking about that and that they need to make a profit, the price seems to be fair.

The price was not cheap, but as eto supporter said they have to make it economically viable after creating it and then having them manufactured etc, so i was happy to pay to get my system working properly. Hopefully they can get to the bottom of why the new membrane isn't working, they are answering emails and i have sent them the video/pictures so hopefully they can help, i had a response from them:

I see you photos of packaging and this packaging is according to our rules. The membranes are of an exellent quality. No doubt there is a problem, but the reason for the problem is not that the membrane is slightly bent, this should have no effect.
When you send me your video (or link) I can maybe sort out the problem. In a previous case, the membrane needed a little bit of air between the layers, so the customer pinned a small hole at a place where are no electronic lines and it solved the problem. It might also help to roll and enroll the membrane a bit.

so it looks like they have had troubles before that they have managed to overcome, hopefully i will get this working and can play my old games on the original hardware and not emulated

[stulish]

i just found this webpage that shows the top and bottom of the CPC motherboard and you can click points on it and it will show you where it is connected to, this could be really useful

[TotO]

i just found this webpage that shows the top and bottom of the CPC motherboard and you can click points on it and it will show you where it is connected to, this could be really useful

Yes, it is related to another cpcwiki topic, done by @pelrun