GR300 in need of servicing

Started by bosetuno, June 14, 2018, 02:50:39 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

bosetuno

Hi!

My GR300 has been in a closet for a couple of years if not more (I became father...) but yesterday I took it from the closet and as soon as I plugged it I realize it was noot working as it should. In my first attempt, almost none of the strings did sound, and appart from the volume and mix, the controls on the guitar did not repond as i expected (a Roland G505, more on this later). Then I tried with a GR700 and the same guitar, and it worked fine, I did not try the edit mode, so the only controls from the G505 I tried was again the volume and mix and both worked fine. I must say that, at some point, I needed to enlarge the trem route on the Roland G505 to fit a normal strat trem. In the process the ribbon cable form the hex pickup to the electronics got slightly damaged. I took it to a friend of mine who is electronic engineer and he resolder the connections in the ribbon. I say this because the problem may be either the GR300 or, the G505 or both. Anyway, this guitar with a GR700 works as it should, but do not with the GR300. I conected these two once more to see what I could discover. I adjusted the hex gain in the G505 (the trimpots in the electronics) to the maximum and I could get sound from the GR300, but the third string behaved weird. It made a noise at the begining and then it went silent until the string was almost muted and then it begun to sound again. I feelt to me like its was saturated a lot to the point of going silent. Also there was a lot of noise when touching or moving the tremolo. And the most weird of all, there was not magnetic pickups sound. Only the hexafuzz and the synth engine. I tried the controls and they seemed to work fine, but it was no magnetic sound coming from the GR300 (while it was on the GR700).

So just to resume,
The third sting is not sounding properly
Theres not mag pickup sound
Strange noises related to the trem.

However none of there are issues with a GR700 uning the same guitar (this is weird). So, my first thought was that it may be related to the G505 cabling. The contact on the ribbon may be bad for the third string and for the ground connection. But if that was the case why did the GR700 sound fine? Is there any differences between the GR300 and the GR700 in the way they manage signals comming from the hex pickup?

Also, if somebody knows a good service center for this devices in europe, I will apreciate it.

Kind regards

chrish

#1
First step would be to spray deoxit on all the pins on the cable in and out jacks. Could be the 24 pin input jack on the GR 300 is corroded.

https://www.vguitarforums.com/smf/index.php?topic=3132.0

Elantric

#2
Quote from: bosetuno on June 14, 2018, 02:50:39 AM
Hi!

My GR300 has been in a closet for a couple of years if not more (I became father...) but yesterday I took it from the closet and as soon as I plugged it I realize it was noot working as it should. In my first attempt, almost none of the strings did sound, and appart from the volume and mix, the controls on the guitar did not repond as i expected (a Roland G505, more on this later). Then I tried with a GR700 and the same guitar, and it worked fine, I did not try the edit mode, so the only controls from the G505 I tried was again the volume and mix and both worked fine. I must say that, at some point, I needed to enlarge the trem route on the Roland G505 to fit a normal strat trem. In the process the ribbon cable form the hex pickup to the electronics got slightly damaged. I took it to a friend of mine who is electronic engineer and he resolder the connections in the ribbon. I say this because the problem may be either the GR300 or, the G505 or both. Anyway, this guitar with a GR700 works as it should, but do not with the GR300. I conected these two once more to see what I could discover. I adjusted the hex gain in the G505 (the trimpots in the electronics) to the maximum and I could get sound from the GR300, but the third string behaved weird. It made a noise at the begining and then it went silent until the string was almost muted and then it begun to sound again. I feelt to me like its was saturated a lot to the point of going silent. Also there was a lot of noise when touching or moving the tremolo. And the most weird of all, there was not magnetic pickups sound. Only the hexafuzz and the synth engine. I tried the controls and they seemed to work fine, but it was no magnetic sound coming from the GR300 (while it was on the GR700).

So just to resume,
The third sting is not sounding properly
Theres not mag pickup sound
Strange noises related to the trem.

However none of there are issues with a GR700 using the same guitar (this is weird). So, my first thought was that it may be related to the G505 cabling. The contact on the ribbon may be bad for the third string and for the ground connection. But if that was the case why did the GR700 sound fine? Is there any differences between the GR300 and the GR700 in the way they manage signals comming from the hex pickup?

Also, if somebody knows a good service center for this devices in europe, I will apreciate it.

Kind regards

Bulk of Roland GR-300's were manufactured between 1980-1982, they were never produced after early 1983.

so all are 35 year old electronics with 35 year old electrolytic bulk capacitors.( the highest source of failure)


GR-300 Service manuals are here
https://www.joness.com/gr300/GR-300.htm
https://www.joness.com/gr300/service/G-303_G-808_GR-300_SERVICE_NOTES.pdf

- there will be a need to have your 35 year old GR-300 bench checked by a service tech to check the internal power rails and signal test points indicated in the service manual   - find someone familiar with electronics with the necessary tools and test gear 


List of Roland Repair centers in EU

https://proav.roland.com/global/support/service_repair/service_centers/
Roland Iberia, S.L.
C/ Llacuna, 161, Floor 2 - Gate 2, 08018 Barcelona,
SPAIN
TEL: +34 93 493 9136


https://www.roland.com/es-es/company/overview/contact_us/

bosetuno

Thanks a lot.

I didn't thought a Roland service center would repair such an old device. I might give them a try, although they are 700 km away from my city.

Kind regards

bosetuno

I cleaned the consctors today with contact cleaner, and nothing changed. :(

But I discovered something new on the process. Hexafuzz works fine. But a soon as I play the third string every sound comming from it stop, not only the one of that string, all of them, including the hexafuzz. If I deactivate the third string form the synth (using the switches) that problem stops (although no synth sound comming from that string). Also, still there no mag pickup sound. I may try to poen it and see if I see something weird, but I think this synth will need to be serviced. Thanks for all the help. I really apreciate it

admin

Quote from: bosetuno on June 14, 2018, 03:33:47 PM
I cleaned the consctors today with contact cleaner, and nothing changed. :(

But I discovered something new on the process. Hexafuzz works fine. But a soon as I play the third string every sound comming from it stop, not only the one of that string, all of them, including the hexafuzz. If I deactivate the third string form the synth (using the switches) that problem stops (although no synth sound comming from that string). Also, still there no mag pickup sound. I may try to poen it and see if I see something weird, but I think this synth will need to be serviced. Thanks for all the help. I really apreciate it

FWIW - the HexFuzz portion of the circuitry is inside the G505 Guitar ) and different than the version in the G303/G808 guitar

Still sounds to me like a Electrolytic bulk capacitors need servicing inside your GR-300

bosetuno


chrish

Did you get your GR300 working again?

bosetuno

I didn´t have the time to take care of it yet. :(

PeakSynthesis

When you do get a little time, you can trace the signal through the circuit and see where it stops flowing using an audio probe....
https://www.diystompboxes.com/pedals/debug.html

I've got a lot of interest in the GR-300 and GR-700 and while I only own the later, I've often got the GR-300 schematics open. Just ask and I should be able to give you a list of individual locations to probe for signal. It's usually just one part along the path that stops things from flowing.

PeakSynthesis

philjynx, what your failing to see is that not all meters are auto-polarity digital meters. Analog meters don't work in reverse and not all digital meters can go below zero volts.

https://www.diystompboxes.com/smfforum/ is a site for people of all electronic skill levels and it serves a worldwide community with a forum currently containing 1120346 Posts in 115410 Topics by 42196 Members. You can't assume everyone has a Fluke or a Beckman meter. Aron, the musician who wrote that article has dedicated absolutely countless hours to spreading stompbox and guitar electronics worldwide to people of all skill levels. He's unquestionably one of the guys who got the whole boutique pedal industry going.

By the way, there's a ton of fantastic info on that forum. I haven't been active as moderator for over 10 years now but I was the only moderator for a few years.