PDA

View Full Version : Toki repair log



cal2
26th July 2009, 06:53 PM
Symptoms: the board would occasionnaly boot. When booting, it runs but without sound. Sometimes the game freezes.

Solution:

- bad soldering on 20 Mhz crystal near the 68000
- bad epoxy block near the sound amplifier.

I resoldered the 20 Mhz crystal near the 68000 and the board now boots and run flawlessly.

Since I had no replacement for the epoxy block, I removed it and made a 2 channel mixer to mix the ym and oki sound output.

Now the game works perfectly with sound.

Womble
26th July 2009, 06:58 PM
The exact faults I had on a Toki - dry joint on crystal and faulty mixer SIP, thankfully I had a scrap Toki to take a working mixer from.

Nice work!

cal2
26th July 2009, 06:59 PM
thank you :)

mastercello
1st March 2011, 07:55 AM
Looks like i have the same problem here with one Toki.

I have sample sounds but no FM sound - so i guess the problem is also the big epoxy block.
Do you have any infos about your "home made" 2 channel mixer?

Would really appreciate any help on this!

Womble
1st March 2011, 08:26 AM
I never made one, my supplier at the time had a badly knackered Toki so I just swapped the mixer SIP in and the problem was fixed.

Hewitson
1st March 2011, 04:09 PM
This is such a great game. One of the very best arcade platformers.

cal2
1st March 2011, 09:13 PM
Hi mastercello,

sorry, I don't have the pcb anymore but as far as I remember, I simply used two amp ops based on a circuit found on the net.

Hewitson
1st March 2011, 09:20 PM
http://www.seekic.com/forum/22_circuit_diagram/25394_TWO_CHANNEL_AUDIO_MIXER.html

Definitely do not use the 741 as recommended! Looks good apart from that.

mastercello
1st March 2011, 10:54 PM
Thanks a lot misters...:)

Really have to look first if the fm audio gets to the sip i guess.
Anyone have a layout of the Toki pcb?

KAISERSIGMAX3
1st February 2016, 09:08 AM
Today I've built a circuit that solved the audio problems with one of my toki pcbs. I had only samples but no FM.
I tried to feed the mixer channel that receives the sampled audio with the FM from the Y3014b but the result was volume imbalance. The samples were overshadowed by the much louder FM.
In some way the original epoxy mixer could balance things, tie the sources together, buffer them and send to the Power amp.
Analysing the Y3014B, any dual opamp and the LA4460N Power Amp, I could trace what one wants from the other. So... the tests began.
Y3014B wants to know the opamp gain needs/limits to work right. So it sends the audio at the right level. If you do not do this its output will be distorted.
I used a LM358N from a really faulty board and everybody knows it has bad reputation in many ways. It is a bit noisy and tends to distort high frequencies.
The 222 ceramic cap (2200 pF) in the FM line tied to ground reduces a bit the distorted high freq impression without much losses and can be omitted in case you use a better opamp. The 20k in the FM line is there to adjust/reduce the Y3014B higher gain in relation to the 2,2k in the samples line. This way all sources will be at the same level.
No need to have -5V in this board to have sound anymore since I used a single power supply opamp.
I suggest any other single power supply dual opamp to replace the LM358 due to audio fidelity, but the circuit won't change.

88673

you'll have to remove the original sip epoxi and connect in its place the pins shown in the diagram. In the board you'll see pin 1 to 20 from right to left.