While the previous articles were about user elements, this chapter will give you information about real SY99 internals. This whole chapter deserves credits to Ola Löfberg (ola.lofberg@hotmail.com).

The following list will decode the numbers of Integrated Circuits (IC):

List of integrated circuits located on the SY99 motherboard.

If you know other codes, please submit them to the FAQ maintainer

The ROM-chips are ordinary 27C1001 EPROMs. They might be read/written with an EPROM reader/writer, if you have on handy. If not, contacting Yamaha might not be a bad idea.

When upgrading the Main ROM from an earlier version to Version 1.3 (or later), one (or both) SY99 CPUs may need to be replaced too (not sure on this).

Both CPUs are appearantly in socket and surface-mounted.

	VOICE-rom v1.1 to v1.2
	Seq-ROM v1.1 to v1.2

CPU change to v1.3 and program-rom (ROM1 v1.3, IC111) should be replaced simultaneously.

During multi edit voice setting of some voices that use the waveform card, more than 2 kinds are assigned. When multi is stored or selected, "ERROR: ID number mismatch!" will be displayed on the LCD display.

When loading one sample data file from a disk, it is possible, in some cases, to load data in exess of the memory size set with the allocation function. This will disable the function to save and load data (ALL DATA) to disk

When MDR memory size is allocated 512Kbytes, and you execute the data input, the data is recieved even if the "memory full" error-message is displayed. However, the data cannot be saved to a disk. (Impossible with both MDR&DISK ALL DATA utilities)

If the "Vol-Low-Limit" setting is assigned to a a controller in the controller set function (DP228) and the controller is moved, the "EFFECT CONTROL" function (DP218) produces an error.

In Voice ROM version v1.1 were spelling errors in the preset multi names:

P-14 Wind Ensemble / Ensemble

P-15 Ethnican / Ethnic

P-16 Folk

Voice ROM (ROM2 v1.2, IC112), Library ROM (ROM3 v1.2, IC113) and SEQ. ROM (v1.2, IC101) can be upgraded separately.

During Pattern (PTN) recording, "PTN REC CANCEL" (SHIFT+STOP)-function does not work with one of the mode buttons pressed (VOICE,MULTI and UTILITY).

AWM sound source sometimes does not perform when the voice is set at "AFM+AWM". (For example, sometimes the sound (with multi-timbre) is not generated, in spite of the existence of note data. This is because the sound wasn't generated in the original voice, due to a defect in the AWM sound source composing the voice of the part.)

LPF (parameter 10) set value of "Effect type 61,62,63" (mod & dly system) is not properly set when MIDI program change is recieved. Although the proper numerical value is displayed, the effect sound is not generated properly.

When changing the initial Delay (parameter 05) of "Effect type 14,15" (Gate Rev type), Rev Type (Parameter 01) becomes other than Gate Rev. Although the proper numeral value is displayed, the effect sound is not generated properly.

With the MDR function off, use the disk function to load a 702Kbyte data file. Next, the data is input with the MDR function, after which the data cannot be saved to the disk.

When saved by the disk save function as ALL SAVE, including sample data, saving is finished using only one disk, although the data amount requires multiple disks. The sample data is lost.

Data disk (sample data) for TX16W is loaded into the main unit and saved to another disk as ALL SAVE. When loading from the disk, an error display appears and loading is not possible.

When MIDI reception channel is set to 2-16 (exept for 1) in voice mode, Bank select data cannot be accepted.

When the power is turned on in a low temperature enviroment, noise is generated occasionaly. However, if the effect bypass is on, the noise will not occur.

Noise occurs in some cases when Effect Parameter is changed while playing the keys in Effect edit. (Example: EFF1 No.45 has been changed to 40 and EFF2 No.5 has been changed to 24, and the EFF1: REV INIT DELAY value is being changed.)

When the entire length of a pattern was set for pattern-record and realtime recording (so it was not affected by the quantize value), it sometimes performed incorrectly and became impossible to operate.

Example: 3/16 time, measure 1, quantize 1/4. 1/4 time, measure 1, quantize 1/2.

Therefore, if the above settings were used, the quantize value was automatically decreased and made recording possible.

Only Seq-ROM can be upgraded here...

Some strange behaviour your SY99 synth might show up one fine day:

	I experimented a bit with the SY99 sample engine (using Avalon, a sample processing software for the Atari ST), and found out, that the 99 can only use the start/attack phase and the loop phase of samples, It never (?) plays any samples behind the loop phase, like one would expect.
	Another strange thing is that if you use a very short low tuned sample and play a high note, the sample engine does miss the loop end and starts to play back the whole internal sample memory (including all the ROM waves). Besides the fact that this is obviously a bug, its nice hearing the ROM in fast forward mode ...
	I always had problems with my SY-99 doing MIDI-SDS (sample dump): - the end of the sample somtimes seems to get lost -> wrong looping - I did successfully circumvent this problem by putting some useless samples behind the end of the sustain loop. (My guess is that the last SDS block is lost in some cases.)
	In an old KEYS (German keyboard mag) I found a little note that the ROM version 1.40 is buggy and having this (and only this) version might be a reason to change ROMs to avoid problems with the sample RAM expansion.
	Effect-unit can freak out when doing program change while playing on the keys.
	When you have a disk with an ALL-file on and you want to overwrite it with a newer one, you can't overwrite if the disk doesn't have enough free space to contain both at the same time. (you'll simply first have to delete it and then save the new one with the same name.
	I have an SY99 and I have noticed that when I load multi's, ALL data, synth daya, etc., from disk, a wierd thing happens. I don't know if it is ALL of the time, but it is certainly often enough for me to have trouble with this. After I load on of these things, and I go to [MULTI], "EDIT VOICE", (PAGE 401 on the top right of the LCD screen) the voice in the 1st channel of the 16 available in the multi, will play even if I am not on that channel. For example: Lets say I have just FACTORY RESET the SY99. The first multi is POPULAR. In that multi are 16 voices, the 1st being EP|GrnDual. The 5th is PL:Echoes6, the 11th is CH:Itopian. I have given these examples as random choices that are ACTUALLY programmed in the DEFAULT settings so we are all on the same "track". Anyway, If you choose [MULTI], EDIT - VOICE, you will be able to curser to any of these voices and play them on the keyboard, you can edit each individual voice, etc. from here. Each voice should play seperately, Right??? Well in this situation, it will (after a FACTORY RESET). If I then load something from disk, and repeat the steps to do a MULTI - EDIT - VOICE, then curser to any given voice that is there(except the voice that is in position 1), the voice that is in position 1 and the voice that is highlighted by the curser will play at the same time. It doesn't matter which voice the curser is on. I still get the #1 voice playing with the voice where the curser is actually on. If I turn OFF the voice in the #1 position, then everything else is fine. I hope that my explanation was at least somewhat clear. Can someone help me with this problem??? I realize that there must be some instruction on the disk that is telling the SY99 to do this. Just in case it is pertinent, I have the SY99 connected to a computer using Cakewalk ProAudio. Please help me...I can't edit my multi's properly when this happens. Thank you for time and consideration. (posted by Steven) Are you sure you have not a software midi thru on into your PC? Did you try disconnecting midi from SY99? (answer by Stefano) I will bet that you have your 99 midi out somehow coming back to your midi in. (maybe through an external sequencer or something). Try this . When you get the problem happening that you describe, go to the midi transmit channel in the SY (page 807) Change the midi transmit channel and the voice that is being triggered (the one one that should not be triggered) will change to another voice . The solution is to try working with your setup with LOCAL OFF(also on page 807). Another thought is that you may have have a master setup selected. Turn it off. (answer by Paul) In the end, set your cakewalk channel to what channel you wish to fuck with on the sy99. make sure you have your main midi channel set to the corresponding midi channel you have set to record on cakewalk (ie. check your edit event in cakewalk to actually vericy youve recorded the correct midi channel). You must also set the local off on SY99, otherwise each note is played two times, one from SY99 keyboard, one from PC. (answers by Joy / Stefano)
	If you discovered another bug or if you can prove one of those mentioned above, please submit your Name, your Email address and - most of all - your ROM versions to the FAQ maintainer