Re: TX802 troubleshooting
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Thank you for sharing that! I have a broken DX7II lying around I could salvage those ASICs from if I have to. In my case, I am pretty sure the OPS2 cannot be broken. It takes the following inputs: - operator frequency - operator amplitude - key on - algorithm And it produces digital audio samples as output. Basically, the EGM tells the OPS2 "produce a sample with your current algorithm at pitch X and amplitude Y". Functional testing (listening to the outputs) proves that my OPS2 can do this job. It is functioning as expected. I can't tell yet if the EGM is functioning as expected. To decide that I need to see if its receiving correct inputs or not. This is what I have ordered a logic analyzer for. If the EGM inputs look correct then it must be broken itself and I will replace it. But because it is such a rare IC, I am reluctant to replace it speculatively. Desoldering is not risk free. Jacob Op vr 10 feb. 2023 om 16:20 schreef <imanjl@...>: I had the same issue with DX7II-FD (which has the same FM engine like TX802). It turned out to be a faulty OPSII chip: YM2604. After replacing the chip the noise issue has been fixed. Finding a brand new or even used YM2604 is impossible these days. My story was related to 10 years ago and I had access to an old Japanese Yamaha service center that had only one set of brand new EGM/OPSII. These chips are very sensitive to short circuit on pins, be careful to not touching them with your tools while TX-802 is turned on otherwise you will damage those in less than a second and make your synth useless forever. |