Kahenraz wrote on 2022-04-25, 16:33:

That's interesting. My MU50 works fine without a battery.

Interesting indeed as I thought they'd be pretty much the same inside.

This is the kind of battery I found in my MU80's, not exactly those obviously but similar style:

My MU80 had been running for years with no issue when suddenly it's started giving me a "battery low!" warning. So I opened it, discovered the soldered battery, removed it all. The unit wouldn't turn on at all.
So I soldered back a battery holder, put a fresh battery in there, and it was working again, so my assumption was that the circuit required continuity. If the MU50 also uses a similar soldered battery, that's surprising if it's different?

Here is what the battery looks like in an MU50.

Kahenraz wrote on 2022-04-25, 16:33:

That's interesting. My MU50 works fine without a battery.

That is interesting. Maybe I should wait for confirmation from someone with a TG300 specifically. It appears it varies by model.

Kahenraz wrote on 2022-04-25, 18:51:

Here is what the battery looks like in an MU50.

That looks like the battery in the TG300 from what I have seen in pictures. Again, it's on its way so I cannot confirm yet. Is that a CR2450?

yup so that's exactly the same as both my MU80, and once removed, devices would not turn on anymore.

Boohyaka wrote on 2022-04-25, 19:10:

yup so that's exactly the same as both my MU80, and once removed, devices would not turn on anymore.

You linked pictures of a CR 1220, which is much different (smaller) that the large coin cell in the MU50 and TG300. That is a CR2450 which is like the size of a quarter or maybe even a 50 cent piece.

yeah...why i said "This is the kind of battery I found in my MU80's, not exactly those obviously but similar style"

I wanted to share what the assembly looked like, not the exact battery type. I googled around but couldn't find it, so share some random picture of a similar assembly.
So yeah my MU80 looked exactly like the picture shared by Kahenraz. If memory serves me well they are 2430.

Boohyaka wrote on 2022-04-25, 19:41:

yeah...why i said "This is the kind of battery I found in my MU80's, not exactly those obviously but similar style"

I wanted to share what the assembly looked like, not the exact battery type. I googled around but couldn't find it, so share some random picture of a similar assembly.
So yeah my MU80 looked exactly like the picture shared by Kahenraz. If memory serves me well they are 2430.

Gotcha. It looks like from what I am reading online that Yamaha kept the same with the battery types as well as the power supply types (they all seem to use 12V DC center +). I guess if someone with a TG300 does not come forward all I can do is remove the battery and see what happens. Why they didn't use battery holders is beyond me. Like the battery would last forever. Or maybe they figured it would last long enough before the produce was EOL 😉

Here's the battery from inside of the TG300....same type.

eightbit wrote on 2022-04-25, 19:45:

Why they didn't use battery holders is beyond me. Like the battery would last forever. Or maybe they figured it would last long enough before the produce was EOL 😉

That's exactly what I thought when I opened it, after being spoiled by Roland's devices all having a nice battery holder. Came to the same conclusion - they probably thought that 15-20 years was fine and nobody would care anymore when the battery died, so it was worth sparing 0.2c per device 😀

I also have a TG300 but haven't had to remove the battery yet, because it still works and looks okay visually.

By the way, is it common for a TG300 to have manually burned and labeled EEPROMs?

I received my TG300 today and while the battery looks just like yours and was still functional, I am not taking any chances. I cut the battery out for now and may add a battery holder someday in the future. That said, it works fine with no battery. It merely says "battery low" on each power on and you have to hit OK to accept and it goes right in and works fine.

Opened up my SC-88 (non-pro) recently to reflow the solder on the RCA jacks, but also replaced the battery. Fortunately the battery wasn't even dead, let alone leaking, but better to be safe than sorry.

Here's my social media thread on it in case anyone wants to see pictures and stuff:
- Mastodon: https://mastodon.sdf.org/@HunterZ/108414739353591268
- Twitter: https://twitter.com/HunterZ0/status/1532775719029178368

I see that you had trouble with your JST connector. I had an issue where one of the connectors was seriously stuck, and trying to force it with a tool was deforming the plastic. In the end, I found that I could simply remove the board with the front panel still attached to perform maintenance, and it worked out just fine. It was a little awkward, but there wasn't any problem with it.

I can also confirm that every synthesizer that I have bought needed at least some reflow on the rear I/O connectors. There is always a crack somewhere, even if connectors that don't have any problems. And this has always fixed instances of dead MIDI and RCA connections.

I also recommend not just reflowing but completely replacing the OEM solder. One of the weaknesses is that these large anchored connectors were secured through a solder bath. And there just wasn't enough solder deposited for a strong, long last mechanical connection. So even if you reflow it, it will probably crack again in the future.

Kahenraz wrote on 2022-07-09, 18:58:

I see that you had trouble with your JST connector. I had an issue where one of the connectors was seriously stuck, and trying to force it with a tool was deforming the plastic. In the end, I found that I could simply remove the board with the front panel still attached to perform maintenance, and it worked out just fine. It was a little awkward, but there wasn't any problem with it.

Yes, I left front panel attached as well. I only unplugged the JST coming from the little power board attached to the transformer, because that cable was only a couple inches long.

I can also confirm that every synthesizer that I have bought needed at least some reflow on the rear I/O connectors. There is always a crack somewhere, even if connectors that don't have any problems. And this has always fixed instances of dead MIDI and RCA connections.

I also recommend not just reflowing but completely replacing the OEM solder. One of the weaknesses is that these large anchored connectors were secured through a solder bath. And there just wasn't enough solder deposited for a strong, long last mechanical connection. So even if you reflow it, it will probably crack again in the future.

Removed and replaced the solder on the output jacks. Was a bit lazy and just reflowed the input jacks, because they were working fine and I'm no longer using them now that I have a separate audio mixer.

Replace with a cr2032 socket on mu-80 make life much easier.

I have had problems with hot glue staying stuck onto solder mask. I'm not confident that it's the right kind of material for keeping things in place, unless it has other components to grab onto for mechanical strength.

I am receiving no MIDI output on the MIDI OUT port (needed for dumping the individual instrument parameters and sequences), and I am trying to figure out why.

It doesn't respond to any sysex data requests that are listed in the owners manual; I double checked I am using the correct device ID (0x10, and it is set to 17 on the sc-55 mkii) and model ID (0x45 for some, 0x42 for others) and checksum.
I also tried "dump all" (press "ALL" and press both instrument buttons simultaneously), and it doesn't output anything that way either.

I also checked the connectivity of all the traces between the lines on the midi out and IC26/24, these are also fine.

I had thought this might be because of a leaky capacitor right here (C6, the big 2200uf one):

I cleaned and replaced it, but I found that the leakage had severed the trace between L1 and pin 13 on the mux/demux:

This is only output for the serial. I'm not using serial, I'm just using MIDI OUT, but I decided to bodge it anyway; that didn't fix it.

So, I am at a loss here. Does anyone have ideas?

edit: I verified that input on the interface works by testing it with the midi thru on the SC-55, and I tested the interface with the MU80 and dumped the parameters using XGEdit for good measure to verify that I can receive sysex messages.

Do I also have to open my Roland SC 55 ST or does mine not have a battery?

Nikita Lita wrote on 2022-09-04, 23:52:

So, I am at a loss here. Does anyone have ideas?

I figured it out. The transmitted data was always being sent on the serial line, rather than midi-out. The reason was there was another severed trace; between the switch and ic18:

Ic18 acts like a mux; in the case of the sc-55mk2, it sends a signal to the cpu which of the selector switches has been selected. If this line is severed, it is always floating, meaning it thinks it’s always set to one of the serial options.

As you can see, this trace is the closest one to the capacitor, so it’s the likeliest to be severed:

Bodging it resolved the issue, I had to turn it over to bodge it directly to the solder pad, then run it over the board to the other side.
If you ever have problem with midi-out or midi-in, this might be your issue.

GuillermoXT wrote on 2022-09-10, 04:01:

Do I also have to open my Roland SC 55 ST or does mine not have a battery?

The SC-55 ST does not have any front panel controls, so there is no use for a battery. I've opened these units up and can confirm that there is no battery present.