Roland SRV-330 LCD Pixels Not Working

[cpsmusic]

Hi All,

A couple of years back I picked up a Roland SRV-330 reverb which was faulty. I managed to repair the fault (power supply caps) and have been using it on and off ever since. I fired up the unit yesterday and noticed that a few of the pixels in the centre of the LCD aren't working. Just wondering if anyone knows whether the LCDs in these units are prone to failure or whether this is more likely to be something else?

Other than the LCD the unit is still working properly.

Cheers,

Chris

 

[user 130681]

If it is characters missing, I would suspect the LCD but for pixels, I would suspect the driver or bad connections.
Investigate with caution, static can kill the LCD completely!

 

[cpsmusic]

This is what it looks like:

 

[user 130681]

Bad connections or driver issues I would say.

 

[AnalogPackrat]

Columnar defects, not isolated pixels. How many of the character cells have this "center column dead" artifact?

 

[cpsmusic]

Apologies for not replying sooner. I haven't been using the unit so the repair has been on hold.

I fired the unit up yesterday and it looks like the problem is getting worse (see attached). From what I can see, there are three columns that are faulty.

I'll check the connections first. If that doesn't fix it, I'll move on to "driver issues" (as suggested above).

Cheers!

 

[cpsmusic]

Another update - I tried cleaning the connections to the LCD however the problem still is there. If anything, it's getting worse. Think I'll try getting a replacement LCD and see if that fixes the problem.

Cheers!

 

[hodad]

One thing I have done with an MC505 is iron the ribbon connector where it attaches to the lcd panel. I don’t see how the SRV panel is wired, but if it’s a flat ribbon connector you might try the ironing trick. I got the idea from someone’s youtube video and it worked pretty well.

 

[cpsmusic]

One thing I have done with an MC505 is iron the ribbon connector where it attaches to the lcd panel. I don’t see how the SRV panel is wired, but if it’s a flat ribbon connector you might try the ironing trick. I got the idea from someone’s youtube video and it worked pretty well.

Do you have a link for the Youtube clip?



This is how the ribbon cable attaches - not sure ironing it is possble.

 

[cpsmusic]

Is there a way to test the output of the LCD driver that would rule out it being faulty?

 

[cpsmusic]

I think I'll post the question about testing the LCD driver in a separate thread just in case people miss it here.

 

[hodad]

Do you have a link for the Youtube clip?

View attachment 105549

This is how the ribbon cable attaches - not sure ironing it is possble.

Not at all like the MC505. Sorry.

 

[58Glammer]

Another update - I tried cleaning the connections to the LCD however the problem still is there. If anything, it's getting worse. Think I'll try getting a replacement LCD and see if that fixes the problem.

Cheers!

Which connections to the display did you clean? Just the plug or did you try to remove the metal frame from the display and cleaned the connection there? I don‘t know the name for these parts inside the display. But I think of this rubber style connection when you remove the metal frame. After a while this connection looses some of the many contacts and then some of the pixels disappear.
Sometimes the metal frame just needs to be tightened to the display or these contacts have to be cleaned.

 

[cpsmusic]

Which connections to the display did you clean? Just the plug or did you try to remove the metal frame from the display and cleaned the connection there? I don‘t know the name for these parts inside the display. But I think of this rubber style connection when you remove the metal frame. After a while this connection looses some of the many contacts and then some of the pixels disappear.
Sometimes the metal frame just needs to be tightened to the display or these contacts have to be cleaned.

I only tried cleaning the plug/pins end of the connector on the main board. I can see that the metal frame around the LCD is held in place by twisted L-shaped pieces of the metal frame - fairly primitive but I guess it works (lol). I'll try (carefully) untwisting the frame to expose the internal connections and then see what sort of state they're in.

Cheers!

 

[Whoops]

Some years ago I was able to fix some yamaha fx units LCD by replacing the electrolytic capacitors that where in the LCD driver circuit, don't know if that would solve the same problem in the Korg unit, but it there lytic capacitors around the LCD on in it's driver circuit change them as it's easy enough and you dont have anything to loose

 

[cpsmusic]

Some years ago I was able to fix some yamaha fx units LCD by replacing the electrolytic capacitors that where in the LCD driver circuit, don't know if that would solve the same problem in the Korg unit, but it there lytic capacitors around the LCD on in it's driver circuit change them as it's easy enough and you dont have anything to loose

I'll add it to the list, thanks for the suggestion!

 

[cpsmusic]

Another quick update - I took the LCD apart.



I can't really see anything obviously wrong. Possibly the SMDs on the right?

Something that had me scratching my head was "how is the data getting to the LCD"? Seemed like some kind of magic

So after a bit of googling I came across "Zebra" connectors - I've never come across them before - you learn something new every day!

Now I get what 58Glammer was referring to (sorry I didn't get what you meant initially). I'll try cleaning the "Zebra" and see if it changes anything.

Cheers!

 

[cpsmusic]

For those interested, this is the connector.

 

[cpsmusic]

Actually, that's wrong!!!

This is the connector, running along the right edge:



I've tried cleaning it but it doesn't seem to have made much difference. The connection doesn't seem that secure so it could be that that's causing the problem with the display.

 

[Rob Flinn]

I have never had much success cleaning that sort of rubber edge connector. It looks to be a generic type of display. Some of these led backlit displays are so cheap now on places like Amazon & ebay that I just tend to replace now on things like SPX90's and LXP15. Sometimes you need to refer to the data sheet because the pin out is slightly different, but that's not too big a deal.