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Double Dragon Arcade PCB - YOU do the repair! - Part 4
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- čas přidán 12. 08. 2024
- This is part 4 of our "You do the repair" video series for the Double Dragon pcb. This time we look into the propositions from part 3 which will lets make further advancements in the sound department. Unfortunately this board turns out to be a board with many, many problems. But of course we are not giving up! Enjoy!
Can’t wait for the next vid!
The Queen of scents? Thank you Hildegard for your interest in this arcade repair! Sorry to keep you all waiting, next part of the repair will be available soon! 😊
@@christophzett im also waiting - i got one on the bench
Dude, keep it up. Your videos are great, I have repair knowledge and can see the way you explain things makes it's easy for someone just learning. Great videos,
Greetz! You likely have completed this video and repair already. Just leaving my contribution! - Appears the board is capable of generating the music just fine. Judge still out on digital samples although sample EPROMs are okay. The IC responsible for playing the digital samples could be at fault, or the 4558 op amps at IC97 + IC98 (Samples iirc) and IC99 (Music iirc) failed preventing consistent playback (more likely). Can verify at the source - Are the samples and music playing, but just not being amplified correctly? These are quick tests that can be checked by tapping into the outputs of the sample and music generator ICs output to something like a pair of cheap amplified desktop PC speakers. Can compare in/out of the op-amps. You can even see the music and fighting noises playing on the scope this way. Also, Great channel!
Couple of tips,
Double Dragon needs -5volts for the Audio to work correctly make sure you have a good -5volts.
Audio channels come from three separate OP Amps IC 97 IC98 and IC99 these often fail and you loose audio channels, the outputs are later mixed to the final mono output also check all those small caps they often go bad also loosing audio. The amp itself also has a audio pop protection capacitor and if that one is bad can mute the whole amp (unlikely if your getting the finger buzz test OK)
Depending on what you hear when probing at the inputs of the opamps you can go forward or backwards in the circuit.
Use an audio probe and "listen" to the digital and in the analog circuits the audio generated something like this from amazons.. Piezo Electric Crystal Earphone Sensitive High Impedance Ceramic Ear Piece very handy to listen... you could also use your scope and look at the generated audio waves and get an idea from the opamp point which way to go..
Also I watched all the videos and board corrosion was glossed over quite a few times PART2 video at 4:16 you can clearly see corrosion evidence most likely from leaking caps over the years... You can also see the very dull solder... more evidence but most important is the via's you can see the traces clearly have dark spots... Thats bad! Often thats corrosion eating the very small traces and often they are broken right where the via goes through the board... You cannot ignore these... At the very least test them but they all need a brush with something like a fiber glass pen, re tin them and in some cases add a link.
Lasty those F chips cannot be underestimated! Highest failure rate and I saw a few in these videos with rust, if not already they will fail, the rust eats them internally.. save the time and get rid of them!
I would like to celebrate the one year anniversary of leaving us hanging 😢
Where have you been man! Come back to us
A couple of thing I would look at. This seems like a mixing issue. If I recall correctly, the coin-up sound is a sample. Try setting the attract mode sound on via the dips and see if the music plays right away, and if it will also play the coin sound. The FM music sounded fine to my ear, so I think that part is working, but the sample seemed warbly. I'm suspecting inconsistent voltages so some bad caps, possibly. Why it takes out the entire FM playback is beyond me. I'd look at the schemas, but I can't see well enough to read them.
Maybe a conflict between music and FX. The last time you started the game, the music stopped right away after the player getting hit.
Probably an issue in the FX section that disturbs the music section.
We need the final chapter..................:)
Great job so far, i'm looking forward to the next one 😉Nice catch on the broken trace under the cpu. Strange that the music is there and sounds fine, but it just won't play!
Sir
When we? will see you
The Triple AND Gate was preventing what type of data from the multiplexer and sound RAM chip? What was the IRQ signal doing to the surrounding sound IC chips?
The choice of troubleshooting the analogue or digital parts of the sound circuit first is a coin toss so either would have been valid. At least the fact that you are getting some sounds seems to indicate that the analogue side is working pretty well. Is I understand it some sounds are samples and some are generated tones so narrowing down which is which would help determine which parts are silent. As you say, tracking down an intermittent fault can be very tricky and time consuming. At least you know that the faults most likely lie on the digital side of the board. Good luck! 👍😁
Hi @Spacedock8 watching this video when you say analog vs digital parts do you mean digital being the ic's and analogue being discrete components like caps-resistors etc?
Cheers Franky
@@YNGBLD80 Hi. No, analogue parts deal with electrical signals that are not the digital ones and zeros (the actual levels of which are determined by the logic technology being used). These tend to be things like amplifiers used to boost varying signals such as sound. These analogue devices are often packaged in the same kinds of encapsulation used for digital devices such as DIP or SOIC. Capacitors and resistors are discrete components and are generally used to "condition" signals such as smoothing voltage ripples on power lines. There is an old argument that "everything is analogue" because in reality there are no such things as true digital signals in electronics, but a great deal of time, effort and money has been put into making circuit technology that behaves as close to digital as possible.
@@spacedock873 OK thank you for the reply and help, so when there is reference to analogue components in sound circuitry is it namely just the amps that id associate as analogue?
@Franky P There are other analogue devices apart from amplifiers. Because computers operate in the "digital domain" and the world is not digital there must be ways of converting signals from the analogue real world to the digital world of the computer. One type of these devices is a generic "analogue to digital converter" or ADC. Other devices are things like temperature sensors which detect the temperature of a probe and produce a digital output representing that temperature. Going the other way you need a "digital to analogue converter" or DAC. Sound chips are one example of such a device but you can also use more basic methods such as a "resistor ladder" and indeed many cheap personal computers in the 1980's used these to generate sound without the expense of a dedicated sound chip.
@@spacedock873 Thanks again SD appreciate the info- I have been doing a little more reading with regards to DAC and PCM interesting stuff. A resistor ladder DAC might read up on that also, finding this stuff quite fascinating. Thanks for being polite enough to help.
When is soon??
For the love of Jesus, post another video😀
Are you ok?
Thanks for asking! I'm fine actually. Just been very busy with my home renovation. Hope to be able to make some more videos soon. Appreciate your interest! ;-)
Hello anybody home
Hello and compliment for the channel. I have some issues with an Hammerin Harry bootleg, like the lack of the green color and the sprites are transparent. The ram and rom check on boot is ok. Thank you for any hint.