Roland DEP5 - Fluoresent Display without function

[rock soderstrom]

Hi folks

I have a defective Roland DEP5 on the workbench here. I love this old FX units, so I would like to repair it.

First diagnosis: the unit turns on, LED meter works, the display does nothing. The voltages at the designated test point all seem to be ok at first glance. The highest voltage 30V is with 37V above the tolerances (32V +/- 2V). This looks like the non-functioning display is not loading this rail and therefore the voltage is increased.

The 30V are for the driver ICs and are switched by a few "digital transistors" DTC114TS to the display.

The fluoresent display is a NEC FIP7CM6 for which I have no datasheet.

With further tests it turns out that the driver components 54563, especially IC14 become very hot, whether with attached display or without!

Further noticeable is the heat traces on the display backlighting, which does not work.

So far the first test, tonight I can probably continue.

My questions , does anyone know about this type fluorescent display? Maybe a data sheet available? Can I test the display without drivers to determine if the display basically works, or is defective, killing the drivers as well?



Service manual
Post in thread 'Roland' Roland

 

[rock soderstrom]

Here the datasheet for the ICs 14 and 15, the 54563 plus photos of the display NEC FIP7CM6.

 

[dmp]

Looks like the display is fried. A custom part?
You could check the voltage between CN2-10 and CN1-9 / at the Q12, 56ohm resistors, and D12 Zener in the bottom left corner. I think that would be supplying the voltage to the display for illumination. Can you tell if the display is working at all with a flashlight shined behind / at the side?
The 30v is not regulated so it will be higher depending on load and wall voltage. But that is just supplying Vs for the M54563P, and they are rated to 50v.
Everything else works, passes audio?
M54563P are cheap and available so you could get those to try, but that display does not look good.

 

[dmp]

This pdf describes how the FIP works on the last 2 pages. The filiment voltage is necessary for you to see anything, then the control signals from the M54563P turn on or off a segment.
I'm guessing your heated filament is fried. Maybe find a non-working one for parts?
Assuming you have voltage across the f f of the FIP.
But make sure Q12, D12 etc is good before putting another FIP in, you wouldn't want to fry another one.

 

[nimus]

Check Q12 (2sb647). If that becomes very hot, too, let the whole circuit cool down. Then switch on again and cool Q12 either with spray or just a little water at your finger tip. Chances are that the display lights up for a moment. If that is the case you found the culprit. I have had that once. Good luck.

 

[Whoops]

I repaired some time ago an Yamaha FX unit where the Display was not functioning,
I googled that problem, and the solution was simple, I just had to Re-Cap all the Lytic caps in the Display circuit, I've done and Voila the display started working again.
I'm not saying that's the same problem with your DEP5, but it's worth considering and it's cheap and easy enough to do

 

[studiog]

Hi, Just joined as found this thread whilst searching for help for exact, and similar, problems. Sometimes the obvious can be clouded when my head makes it more complicated than it should be. So solution one, and this thread resolved it...was a broken trace, literally a hairline scratch, almost invisible, meaning there was no voltage getting to pin 8 on CN1 from Q12. The second unit... Ive finally got the power rails working but the display only has about 50% of the character segments working. Im currently assuming its either Q23 / Q24 or IC27. Display is fine in a doner unit. A WIP for today but any advice greatly appreciated. P.S. the Roland capacitor adhesive has really started to corrode the board on this one. It almost looks as bad as battery leak damage.

 

[Adrian55]

Hi folks

I have a defective Roland DEP5 on the workbench here. I love this old FX units, so I would like to repair it.

First diagnosis: the unit turns on, LED meter works, the display does nothing. The voltages at the designated test point all seem to be ok at first glance. The highest voltage 30V is with 37V above the tolerances (32V +/- 2V). This looks like the non-functioning display is not loading this rail and therefore the voltage is increased.

The 30V are for the driver ICs and are switched by a few "digital transistors" DTC114TS to the display.

The fluoresent display is a NEC FIP7CM6 for which I have no datasheet.

With further tests it turns out that the driver components 54563, especially IC14 become very hot, whether with attached display or without!

Further noticeable is the heat traces on the display backlighting, which does not work.

So far the first test, tonight I can probably continue.

My questions , does anyone know about this type fluorescent display? Maybe a data sheet available? Can I test the display without drivers to determine if the display basically works, or is defective, killing the drivers as well?

View attachment 101623
View attachment 101624View attachment 101625View attachment 101626
Service manual
Post in thread 'Roland' Roland

I have the same problem but IC14 is nearly fried.
No 30v (4.7v) but there’s 5v yet both show short when tested in regards to ground.
At first screen was turning on but it has a crack.
Ordered new IC14 but I can test circuit after I remove it not time just now.
Any luck with your one??

 

[rock soderstrom]

No, sorry.

 

[studiog]

I have the same problem but IC14 is nearly fried.
No 30v (4.7v) but there’s 5v yet both show short when tested in regards to ground.
At first screen was turning on but it has a crack.
Ordered new IC14 but I can test circuit after I remove it not time just now.
Any luck with your one??

I too tried replacing IC14 & 15. I think i got fakes off an ebay seller as they went red hot. Got some alternatives and they still didnt work but they didnt go red hot. Display was fine in another unit. I think its something other than these chips. You obviously need to get the voltages working correctly first. I put my defective one aside to work on other stuff but will be going back to it at some point. It's not the whole display thats not working on this one here just many of the line segments within each character. Also the 30V test point has read well above that on all the units ive worked on and the displays showed signs of being burnt in the glass ....but they all still worked.

 

[Adrian55]

I too tried replacing IC14 & 15. I think i got fakes off an ebay seller as they went red hot. Got some alternatives and they still didnt work but they didnt go red hot. Display was fine in another unit. I think its something other than these chips. You obviously need to get the voltages working correctly first. I put my defective one aside to work on other stuff but will be going back to it at some point. It's not the whole display thats not working on this one here just many of the line segments within each character. Also the 30V test point has read well above that on all the units ive worked on and the displays showed signs of being burnt in the glass ....but they all still worked.

Removed the IC 14 and short on test points is gone.
Waiting for new ones to come and will see.

 

[Adrian55]

Replaced the chip and it came back to life but still half readable.
Display has a crack and one of the filaments heats up more only where crack is but you can see other filaments going slightly red which means that Voltage is a bit too high.
My voltage seem to be around 39v and that makes me wonder if It is fixable as it seem to come straight from half bridge rectifier if I’m not wrong.
Few test to be done tomorrow but looks like I’ll be using editor from now on.

 

[Adrian55]

At this point I wonder if it’s screen or one of the controllers as digits ie. IR2E02.
Q23&24 seem to be working ok also I replaced Q12 but it’s heats to 100 degrees but the old one seem to do same.
As above voltage is 39V but IC14&15 can accept up to 50V.
I mean screen has a small crack but haven’t lost to vacuum so at this point it’s stand still until I get my hands on replacement screen.

 

[studiog]

View attachment 109236
At this point I wonder if it’s screen or one of the controllers as digits ie. IR2E02.
Q23&24 seem to be working ok also I replaced Q12 but it’s heats to 100 degrees but the old one seem to do same.
As above voltage is 39V but IC14&15 can accept up to 50V.
I mean screen has a small crack but haven’t lost to vacuum so at this point it’s stand still until I get my hands on replacement screen.

Don’t have schematics to hand but ir2e02 usually just drives a bar graph led in Roland stuff nothing else

 

[Adrian55]

Don’t have schematics to hand but ir2e02 usually just drives a bar graph led in Roland stuff nothing else

You’re absolutely right. I must have been tired last night writing and then posting it.
Well I don’t have bloody idea why there is segment spillover then my guess at this point would be that display is gussed.
I think about getting editor for it and that will do me.

 

[studiog]

Yeah i know that tired brain fog feeling. i’m almost convinced there is some fairly common issue with these units and i’m determined to find the problem. I have one with a display that works fine in other units but in one unit the number eight for example will have a few segments missing. Same for all characters.…a few segments missing but the rest are working. Are you 100% sure the fip driver chip was genuine and not fake ? Have you changed both chips or just one ? Ive had to move onto other things recently but will get back onto the faulty DEP5 as the other two i got back up and running fine. I’ll post any new findings here fella.

 

[Adrian55]

I am suspecting other chip to be bad but hasn’t not been convinced enough yesterday.

The chip that got burned was replaced with “fake” replacement and screen turns on but I’m not sure if it’s actually working or not.

I’ll desolder it today socket it and the I can swap them over and check other chips I’ve got.
I will comeback to report my findings.

Ps. Looks like 39~V isn’t at any point adjustable as it’s the voltage that gets straight from the transformer via rectifier diodes and into drivers.

 

[studiog]

I am suspecting other chip to be bad but hasn’t not been convinced enough yesterday.

The chip that got burned was replaced with “fake” replacement and screen turns on but I’m not sure if it’s actually working or not.

I’ll desolder it today socket it and the I can swap them over and check other chips I’ve got.
I will comeback to report my findings.

Ps. Looks like 39~V isn’t at any point adjustable as it’s the voltage that gets straight from the transformer via rectifier diodes and into drivers.

May be worth adding sockets for both so easy to swap around and change etc. my problem isnt identical to yours but i have a feeling i used an equivalent chip (that worked) rather than 54563 will have to check but i do rememer the new 54563 off ebay cooked bacon in seconds and the other one didnt.

 

[Adrian55]

I already socketed burned one.

Another one installed and I swapped chips round but unfortunately it’s not working. :/
What is that RA2? What’s the purpose of it??

 

[rock soderstrom]

What is that RA2

Resisitor network, 8x 47k in one package.