XV-5080 sound issues

Forum for JD, JV, XP and XV synthesizers from 1990's

XV-5080 sound issues

Postby drb27 » 02:36, 19 January 2012

Hi All,

I recently acquired an old used XV-5080 which initially appeared to be in great condition. However, it has developed a fault which pretty much renders the device useless.

There is a crackling noise appeared on a large number of patches. The noise only happens when notes are being played, but this is not your classic polyphony issue as the noise happens even if a single note on a regular, built-in patch is being played. Some patches are affected worse than others, and a small number are not affected at all.

The noise itself sounds a bit like a noisy pot being wiggled on an amplifier, but a bit more digital than that (if that makes sense). I'm pretty sure that the noise is being introduced BEFORE the effects, as I can hear reverb on the noise. Also, the noise appears equally on all outputs - jacks, S/PDIF, and even the headphone output on the front panel.

Do you think the unit can be repaired? Any other pointers you can give me? All help appreciated - I was just getting in to learning this classic piece of kit and now its ruined!!

Thanks in advance,

David
drb27
 
Posts: 3
Joined: 02:27, 19 January 2012


Re: XV-5080 sound issues

Postby Hanon_CTS » 02:55, 19 January 2012

Hello David,
Could you try disabling the effects to determine if it is one of them?

In particular,
I believe that it may be one or more of the following effects:
LoFi (Effects that intentionally degrades the sound
quality)
50: LOFI COMPRESS
51: LOFI NOISE
76: STEREO LOFI COMPRESS
77: STEREO LOFI NOISE

Cheers, Hanon
Hanon_CTS
 
Posts: 31
Joined: 21:16, 14 June 2011

Re: XV-5080 sound issues

Postby drb27 » 03:00, 19 January 2012

Hi Hanon,

Thanks for the quick response! I don't believe this is one of the effects - it actually drowns out a lot of the patches, being as loud as the patch itself.

Am I right in thinking that if I press the Effects on/off button and make sure all of the four effects sections say 'Off' then I am not applying any effects to the patch at all?

I have done a complete factory reset too, which does not help.

Thanks again,

David
drb27
 
Posts: 3
Joined: 02:27, 19 January 2012

Re: XV-5080 sound issues

Postby Hanon_CTS » 03:11, 19 January 2012

Yep,
you're right, that turns them off.
I thought that I'd suggest the easy test first.
It may be an internal defect, and require repairs.
Cheers, Hanon
Hanon_CTS
 
Posts: 31
Joined: 21:16, 14 June 2011

Re: XV-5080 sound issues

Postby drb27 » 01:43, 20 January 2012

UPDATE: The problem seems to diminish significantly as the unit warms up - over two hours or so after power up.

Any clues?

David
drb27
 
Posts: 3
Joined: 02:27, 19 January 2012

Re: XV-5080 sound issues

Postby 0kk0p3kk4 » 20:43, 28 July 2016

drb27 wrote:UPDATE: The problem seems to diminish significantly as the unit warms up - over two hours or so after power up.

Any clues?

David


Did you get a hang of it?
0kk0p3kk4
 
Posts: 68
Joined: 07:53, 7 May 2014

Re: XV-5080 sound issues

Postby genesis92 » 12:12, 9 January 2017

same things on the mine. there's some noise when playing phrases. but not as much as yours.
I've replaced the faulty encoder and I will make a recap on the power supply unit and see if it solve the problem.
+5V is measured @ 5.209V on the PSU output
if the crackling noise is on all outputs (even spdif) perhaps a master clock problem?

and the culprit seems to be....IC13...
when unit is warm and the sound is ok, if I use freezing bomb on iIC13 the crackling noise appears....until the chip warms again...

I will try to check all the master clock chain components and especially the TLC2932 PLL.

it's not a power supply voltage problem because I've modified the feedback loop to get 4.97V instead of 5.2V and the noise is here.
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris

Re: XV-5080 sound issues

Postby genesis92 » 19:31, 9 January 2017

It seems to be fixed....C71(10uF 16v) or one in parallel capacitor (or the regulator) seems to be the origin of the trouble.
adding a cap in parallel while playing the sound remove the crackling noises. so it seems to be a supply decoupling/bypass capacitor problem!
now I have a 100uF capacitor in parallel of C71 for test and I'm waiting the unit to be cold but at this time I have no more crackling sound.

when I measure the voltage across the capacitor there is an ripple on it.
adding capacitor remove this ripple.
I must go further to see if it's a lack of decoupling or the 3.3V regulator the problem.
a video showing when that when I press the button to add a capacitor in parallel, the noise diappears
https://youtu.be/vwuwc0zHgW4
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris

Re: XV-5080 sound issues

Postby genesis92 » 22:45, 9 January 2017

here are some pictures of the tests
where the scope is connected with short ground link (ripple noise method)
Image

and here the results
Image
420mV of ripple noise!
the frequency seems to be near 378KHz
Image
and now with the cap connected with the same scale as before
Image

the current is measured at 350mA max. (important for me to choose a new regulator)
Image

done:
- PSU feedback modification to get 5V instead of 5.2V
- clock + PLL check

-> next steps:
- PSU recap - (tomorrow)
- try to replace the LDO regulator because the bypass caps seems to be ok -> faulty (noisy) regulator?
I'm searching for a good replacement part because the original is hard to find.
the output noise must be near 55µV and rejection ratio at least 64db with line regulation near 15mV and load regulation 25mV to be the closest possible to the original one.
Image
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris

Re: XV-5080 sound issues

Postby genesis92 » 19:26, 11 January 2017

Confirmed! it's a power supply problem.
I've replaced the voltage regulator and the problem is gone! \o/
and even before to recap the PSU and without the test bypass capacitor connected.
Ripple is now at 90mV instead of 400mV

a video before:
https://youtu.be/4nW7qyra8vM

and after replacing the regulator
https://youtu.be/BAUrQvggS78

solved! :)

I must make more tests because the capacitors even if they seems ok with multimeter, they looks bad under LCR meter with huge ESR.

so for someone having the same trouble the best to be sure is to replace:

-C79 -> the mine was measured at 1uF instead of 47uF! -> replaced
-C71 -> the mine was measured at 6uF -> replaced
-C75 -> the mine was measured at 5uF instead of 10uF -> replaced
- and at the end the LDO if replacing caps doesn't work



But my unit works well now with the new regulator :)

When the bypass capacitors are replaced the ripple is even lower with the new regulator.
I don't want to go back and test with the old original LDO but you can try in first intention to replace the three aluminium capacitors C79 + C71 + C75 to check if the problem is solved only by replacing these parts before to go further.

well well well....C249 is measured at 13uF instead of 47uF....I think the rack is running hot and the big problem is the capacitors....aluminium capacitors doesn't like heat....a complete recap could be a good idea I think.....
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris

Re: XV-5080 sound issues

Postby genesis92 » 21:24, 16 January 2017

well. recap of SMD aluminium caps is done for the mainboard and I HIGHLY RECOMMEND to the XV-5080 owners to do the same (or ask to a service dpt to do it).
I have used Nichicon 105°C 2000HRS CD serie caps as replacement (5000HRS were not available with low esr and same size).

I think pictures are better than words
Image

yes! nanofarads!
Image

I've measured each old cap value and made a table
Image

no comments! now I'm pretty sure the regulator was not the origin of the problem but the lack of bypass capacitance!
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris

Re: XV-5080 sound issues

Postby genesis92 » 15:13, 1 February 2017

all works well but even with a psu recap there's lot of ripple at the psu output. the output voltage is badly regulated. It's not a PSU failure, it's from design.
you can't hear it but the PSU make a buz noise at the boot and I don't like it. the ripple when a light load is connected (boot of the XV is near 880mV peak to peak for the 5V output!)

it's a very bad designed PSU (no controller only a quasi resonnant flyback design with feedback) and I strongly encourage people to replace this bad PSU by a good one.

I've used a XP power ECM40UT33 medical grade for my XV. it's not so expensive 45€ and it's a good quality one with lot of protections and good line/load regulation. (I've compared several other models from RS, traco, artesyn etc)
some simple wiring is required and 3 holes to drill but it gives you peace of mind.
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris

Re: XV-5080 sound issues

Postby genesis92 » 14:05, 3 February 2017

Voila :) the new PSU is installed (left) and the old one (right)
Image
User avatar
genesis92
 
Posts: 19
Joined: 11:01, 9 January 2017
Location: Near Paris


Return to JD, JV, XP and XV series

Who is online

Users browsing this forum: No registered users and 1 guest