GR-1- Only mono output

Started by Silas Lang, January 04, 2018, 08:41:55 AM

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Silas Lang

As the title states, when I plug both output jacks of my gr-1, only one of them outputs audio. The strange thing is that when I check them separately, both works flawlessly. Even more strange: if I unplug slightly one of them, keeping it still plugged halfway, voilà, stereo output again, albeit a little quieter. And this irrespective of which one I "unplug slightly". It seems quite esoteric to me. Any other user has experienced this?

As a side note, the unit has also started to smell "funny". Should I expect an imminet failure?

admin

#1
That's common with electronic gear older than 25 years oxygen oxidizes many of the electrical contacts inside including the output jacks Small application of Caig labs Deoxit spray on the jacks and inserting quarter inch plugs five to ten times typically cleans and knocks off the oxidation on the internal electrical contacts on the jacks and restores normal operation

More

http://llamamusic.com/gr1/gr-1_info.html

AngeloEvs

The funny smell may be  capacitor leaking.    Regards the mono output, use headphones  and insert into the headphone Jack.   You should hear signal out in both headphones.   If you do then the fault, as already mentioned,  is most likely with the line output jack or the solder connections to the PCB, etc.       Also, one of the line jacks outputs both left and right if that is the only line output with a jack inserted into it.   It is marked as mono out.     

Silas Lang

Thanks a lot for the replies, guys. I forgot to mention that, when using headphones, still just one channel sounds, so it's not an issue with the output jacks. Could it be a faulty capacitor, the same that provoke the nasty smell?

But suddenly it has appeared the message "Batt Low", so it seems the battery needs to be replaced. I can't see any relation between the battery and the output stage of the unit, but, could this be the cause of the output problem?

Silas Lang

Now it has stopped working definitely, so time to spend money I guess

chrish

Quote from: Silas Lang on January 05, 2018, 02:15:10 PM
Now it has stopped working definitely, so time to spend money I guess
it seems that a lot of those GR 1's smoke themselves to death.

admin

Quote from: chrish on January 05, 2018, 07:07:09 PM
it seems that a lot of those GR 1's smoke themselves to death.

Really no different from any other electronic product from 1990. In 2017 (27 years later) Most will require electrolytic bulk caps replaced  , as the original type employed are only rated for 10 years


chrish

Quote from: admsustainiac on January 05, 2018, 07:21:26 PM
Really no different from any other electronic product from 1990. In 2017 (27 years later) Most will require electrolytic bulk caps replaced  , as the original type employed are only rated for 10 years
I think I remember reading on the forum that a member smoked two of them.

https://www.vguitarforums.com/smf/index.php?topic=14538.0

Quote: "Like most digital electronic gear that sits unused for years,  the electrolytic capacitors in the power supply that dry up  - cease to function and then allow AC current where it does not belong and it smokes

https://www.vguitarforums.com/smf/index.php?topic=8751.msg113837#msg113837


In all modern electronic devices , there is a well known phenomena of the bulk electrolytic caps in the power supply drying out and cease functioning after 10 years. This is the main reason old camcorders die.
http://www.epanorama.net/newepa/2010/03/23/electrolytic-capacitor-failures/


A good tech can diagnose a fault in the power supplies -  but good luck finding one in 2015!"


Silas Lang

Quote from: chrish on January 05, 2018, 09:17:47 PM


A good tech can diagnose a fault in the power supplies -  but good luck finding one in 2015!"

I'm not in a hurry. Fortunately I have my current guitar synth needs covered with my GR55, VG99, GR300, GR700, GR100 and GM70 :-)

Nevertheless I'd like to repair the GR-1 in the future. It tracks almost perfectly, and more accurately than my GR55; curious considering it was made so long ago. But again the GM70 is the more accurate guitar to midi device I've ever used (haven't tried Tripleplay). Slow, yes, but track is very good. And it was made in 1986. Guitar synth technology hasn't always been a way forward.

chrish

#9
Quote from: Silas Lang on January 06, 2018, 04:03:39 AM
I'm not in a hurry. Fortunately I have my current guitar synth needs covered with my GR55, VG99, GR300, GR700, GR100 and GM70 :-)

Nevertheless I'd like to repair the GR-1 in the future. It tracks almost perfectly, and more accurately than my GR55; curious considering it was made so long ago. But again the GM70 is the more accurate guitar to midi device I've ever used (haven't tried Tripleplay). Slow, yes, but track is very good. And it was made in 1986. Guitar synth technology hasn't always been a way forward.
sounds like you got it covered. I sent the output of the GR300 into a digital delay line  and then into a boss sy-300 Guitar synth last night and I have to say wow. 

And to think I totally discounted the GR300 because of its age as old tech. There's nothing else like it.

The quote in my previous thread was actually from Steve in another thread.

I had zero understanding of capacitor burnout till I started hanging out here.

Silas Lang

Quote from: chrish on January 06, 2018, 05:14:56 AM
sounds like you got it covered. I sent the output of the GR300 into a digital delay line  and then into a boss sy-300 Guitar synth last night and I have to say wow. 


It seems a clever solution to expand the limited sonic palette of the otherwise great GR300. I wasn't convinced by the SY300 based on the demoes I saw when it was released (too much guitar midrange for my taste), but your brilliant idea makes me consider purchasing one in the near future.

RogerVG8EX

Quote from: Silas Lang on January 06, 2018, 08:05:26 AM
It seems a clever solution to expand the limited sonic palette of the otherwise great GR300. I wasn't convinced by the SY300 based on the demoes I saw when it was released (too much guitar midrange for my taste), but your brilliant idea makes me consider purchasing one in the near future.

I tried one when it came out. I wanted to get a decent GR-300 sound but it was impossible. All the sounds are too "dubstep" in my opinion, and it should be cheaper.

chrish


AngeloEvs

See the post just below this one, I replied and covered loss of output on my GR1 and cause.     If there is no output then you or someone needs to check the supply voltage to the output integrated circuit as described in my post.   It is not a difficult repair to replace the capacitors, any reasonably qualified engineer should be able to do it with the GR1 service manual. 

The GR1 service manual is available for free to download from here        http://www.synfo.nl/pages/servicemanuals.html


Silas Lang

Quote from: AngeloEvs on January 08, 2018, 02:19:22 PM
See the post just below this one, I replied and covered loss of output on my GR1 and cause.     If there is no output then you or someone needs to check the supply voltage to the output integrated circuit as described in my post.   It is not a difficult repair to replace the capacitors, any reasonably qualified engineer should be able to do it with the GR1 service manual. 

The GR1 service manual is available for free to download from here        http://www.synfo.nl/pages/servicemanuals.html

Thanks a lot for the reply, AngeloEvs, but I cannot see the post you are referring to.

AngeloEvs


gumtown

with the stereo output working if one of the jacks is inserted most the way in, but stops when fully inserted implies the socket auxiliary switch contacts are worn.
Replacing the output sockets might be the solution.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/