Can't thank you enough for doing this! I just fixed my SPX90 when I ran into this video. Self taught in basic electronics and it's scary that I could actually understand your description of the audio flow through the box, even if I have no idea how it all works. Peace.
The biggest thing when looking at videos like this, to me, is always thinking "at least he names the manufacturers and type of the parts, I'd need the right values and temperature rating and whatnot, I wonder where to get them". The bottom plate removal was brilliant, hadn't even thought it might be a removable plate instead of a solid chassis like amp chassis often are. Makes servicing one so easy. Those missing knobs/buttons are pain in the ass. I got a Rocktron Intellifex where the power button hat had just disappeared at some point of the time, and I have no idea where to get a replacement or even a fit.
As far as I can tell the Yamaha Rex50 is a somewhat stripped down version of the SPX90 aimed at guitarists which added distortion and the removed parametric eq and a couple of others. The specs are essentially the same but there are a lot less chips on the board of the Rex50and it only uses a single Burr Brown PCM54HP D/A chip. I'm wondering how they got away with using only one on what is essentially the same device.
Very interesting, I picked one of these up a few years ago, in almost new condition and still working well, If it ever goes bad I'll have an idea what could be wrong thanks to your well made video, thanks, and I'll be watching more, so I've subscribed.
Great video and explanation - thanks. A quick query - the bipolar caps on the main board are in the audio chain, however my understanding of the schematics shows the monopolar caps are for smoothing the voltage supply of the op-amps. I may be wrong as I am just a hobbyist !! If so, should the monopolars be audio grade, or just routine. Thanks for any advice.
I have a unit that is giving me audio that cuts out when the effect is turned on. Bypassed audio is fine, effect on it cuts out. Is this the output board that is failing from age? What else can I check? I'm only very basically competent with electronics. Any help is greatly appreciated, thanks!
Most likely the backup battery just needs replacing and holding down the buttons to reintialize it and clear memory and it will be up and running. I have an spx1000 same config
That is the reason other companies could not produce same effects like symphony, because Yamaha used their own DSP that were made only for Yamaha in their own factory.
Hey mate, I think I’ve got logic problem here with ROM IC151 but I’ll start with saying that I recapped power supply as unit wasn’t turning on at all. After recapping unit turned on with display showing blocks and numeric display was showing 33. I checked all the voltages and they’re within spec. I noticed that RAM’s are getting extremely hot that’s first IC145 is getting warm alongside with couple others. I was suspecting relays but as soon as I took out ROM unit went crazy showing random things on both screens and suspicious relay works like a charm. My question would be if ROM is corrupted and why would RAM got so hot?(possible processor damage due to failing SMPS?)
Thanks to your videos I fixed two SPX90s I bought for next to nothing. The power supplies were indeed the culprit. I came across another one the other day that passed audio but the display was showing strange Asian looking characters. I passed on it because I was suspecting more issues than just the power supply. Any knowledge on issues like these?
It's probably a failed IC. I have repaired a number of these SPX processors and had to change some out. You need to be able to trace the audio path in and out of the machine to see if it's happening in the analog or digital section.
Hello. A few months ago, bought a Yamaha SPX90II from eBay where seller told the problem was the main on/off switch. So, I open the unit and tested the switch and it was good. As soon as you powered up, the screen lighted but fade out. I did a search in internet and saw the PS caps were a problem of that units. I bought a kit in eBay from Canada, I’m from Puerto Rico. When the caps were replaced the unit kept on. I have not tested with sound signal until a few days ago. I noticed in the volume level lights of a mixer were the unit output where connected, that an increasing pop was sounding repeatedly just one volume light up. Like: uuum-pop, uuum-pop, repeatly. Where do I have to check and which parts? Thanks in advance!
Only just found your question so probably a bit late to the party but I doubt a battery change will resolve that issue. I have repaired a number of these SPX processors and usually audio faults are caused by failed ICs. In any case, if the battery in your unit is old, it is a good idea to replace it before it leaks all over the board and does damage.
How did you determine the caps are non-polorized? Do you typically stock capacitors or do you order them (in packs) as needed? I'm just starting with equipment repair and I like your approach to repairing 30 year old gear, to use in your studio. Thanks for all these videos.
There will not be a negative stripe on the capacitors, the schematic in the service manual will also not show polarization on them. You see the same value capacitors throughout manufacturers gear, so I just buy in bulk. Thanks for watching!
@@bradthx Hi There, I have a strange fault on a SPX900 which will change programs when tapped & then come up with "NO DATA" if continued to tap on the PCB. I have reflowed any solder joints that looks anything like suspect. The PSU is recapped & it passes audio as it should & sounds great. Whole unit is fully recapped. Is it a possible RAM fault ??
Any idea if the display can be directly replaced with a cheap 1602 as found on ebay or does it need additional hardware? I note on the back of my display it seems to have a controller and driver chip on the display itself.
After eight months, you've probably moved on from this, but I wanted to do the same thing on mine. I think it's that standard "HD44780" type like they all use, but there really isn't enough space to do much. Their LCD circuit board only protrudes on the top and bottom of the display by about 3mm. Most of the available cheap ones have connections at the top or bottom, and even the ones with a header on one end have too much board to fit. On top of that, I think the holes are a bit off from the more common spacing. -Sorry :-(
Thank you, I have the samle problem with the power supply. I read it still can be life danger to touch a PSU, even if its not plugged. I know how to solder, but I don't have knowlede about electronics so much. Isn't it very dangerous for an amateur to try what you are doing here ?
