Roland JD-800 Repair, Restoration & Modification

Another great work restoring a JD-800. 

Thanks for Scott MacLean for this complete video! 

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Again the Gandalf in a great performance!

This is the famous Gandalf The White - The Roland JD-800 Custom White Synth.

It is really a nice white custom mod by Customsynth.
So, another great performance with it and its great sound! 

Turn up the volume!

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And here with other great synths:

 

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More great music playing with the Gandalf

One more fantastic playing with the Gandalf. 

Another great example of why I love the JD-800 so much, a great example of what this fantastic machine does.

Thank you David C. Lovelace for another fantastic presentation!

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A fix for trailing distortion after every effects based patch on JD800

This post cames from the Facebook Group Roland JD-800 / JD-990.

Our colleague Igor Kopman posted about the problem, and here what appears to be the main trouble, so he posted this first solution:

"Hi guys. Many people have Trailing distortion after every effects based patch on JD800. This is the DAC problem. Very easy to fix. Just replace the R100 resistor to another with a lower resistance on output board, and the problem will gone."

Here's the board: 

The circuit:

470k. Color code Yellow Violet Yellow Gold:

This one: 

Pay attention to this:

Our colleague Julian Camp replied:

Igor Kopman the original resistor has to be measured out of circuit. Do you still have your original and what does it measure? The schematic and colour code says it should be 470k

So after more replies from many colleagues in the group and thanks to  Igor Kopman  for presenting this need, Julian Camp posted what appears to be a more simple solution: 

Julian Camp

Replace VR1 with a high quality multi turn pot and it will fix the issue. The original VR when turned all the way counterclockwise or clockwise reads around 440ohm. The VR wasn't going low enough in resistance. Resistors R100, R101 and R102 tested within spec.

Thanks to everyone for supporting this great music machine! I love this synth and all you!

Manuals available: 

If you need the JDs Service Manuals plus all the others JD' manuals just enter at this page:

Manuals: JD800 and JD990 (Updated)

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The original topic text messages for credits, many people helped for sure!

** Igor Kopman

Hi guys.  Many people have  Trailing distortion after every effects based patch on JD800. This is the DAC problem. Very easy to fix. Just replace the R100 resistor to another with a lower resistance on output board, and the problem will gone.

** Radek Tymecki

You think that changing the resistor is the key? Caps are ok?

** Jym Mccullough

Can you be more specific on "lower resistance?" How about an exact value that works?

** Kevin Nolan

Jym Mccullough It looks like a 46 Ohm Resistor - hard to tell but I think I'm seeing Yellow-Blue

** Igor Kopman

Jym Mccullough I will open my JD800 and check it.

** Igor Kopman

Jym Mccullough Ok the resistor is 137k

** Kevin Nolan

Igor Kopman Yup - 46 Omhs - 137k - I was almost right 🥴 (ye know - on the cosmic scale of things...)

** Julian Camp

Igor Kopman the original resistor has to be measured out of circuit. Do you still have your original and what does it measure? The schematic and colour code says it should be 470k

** Igor Kopman

Julian Camp I think it was 240k or 270k

** Julian Camp

Igor Kopman that's what it would measure in circuit. Did you measure it out of circuit?

** Julian Camp

You have to take the resistor out of circuit to measure it. Mine reads 480k. The schematic and colour code shows it should be 470k. So this resistor shouldn't be the issue unless my cheap meter is correct and it is 10k out of spec. Will replace with a … Ver mais

** Julian Camp

470k. Color code Yellow Violet Yellow Gold

** Gilberto Strapazon

Thanks Igor Kopman!

Please, you or someone else with the same trouble may check about the measure out of the circuit of the probably damaged part?

This topic will be replicated at the JD800center if we have more info.

Appears the kind of problem with a easy solution and this means Gold!

I'm saving all the topic (with all replies for credits) for a post at my site.

I'm sure many people will be after this information too.

Thanks for more replies so I will soon post at the JD800Center too.

** Jym Mccullough

Gilberto Strapazon Thanks for maintaining your website. I've looked there many times for info and tell others as well.

** Julian Camp

I will replace the three resistors going to the trimmer pot and report back. Will be replacing with original values. R100 - 470k, R101-1M, R102-200k.

** Eric Vaubel

My JD-800 and my PCM-80 both do this. Will investigate!

** Julian Camp

UPDATE!

Replace VR1 with a high quality multi turn pot and it will fix the issue. The original VR when turned all the way counterclockwise or clockwise reads around 440ohm. The VR wasn't going low enough in resistance. Resistors R100, R101 and R102 tes… Ver mais

** Gilberto Strapazon

Julian Camp great! Simple and very effective!

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Links for other JD sites, stuff and foruns. Permanent list

The links are unordered. Some sites may requires translation like translate.google.com


Notes:
1-Some sites may be no more available, so please notify me as my time is limited.
2-If you own a website with technical material (no sales promotion please) send me a message so I can add it here.



The two best foruns for the Roland JD-800 and JD-990:

• JD-800_Tech Yahoo Group. This is a group covering technical, repair, performance, and programming aspects of the Roland JD-800 synthesizer. The group is active and the spammers removed.
• Roland_JD-990 Yahoo Group. For all users of the Roland JD-990. This group is intended for the sharing of links, Useage info, Tips/tricks, & user patches.

Tact Switch Black - up/down, decr./incr

(replacement for 13169696)

vintageplanet.nl  - Parts Service for Vintage Synthesizer - They have parts for JD-800 and JD-990.





VintageSynth One of the most famous reference for every synth.


Harmony Central  This is one of the best site and foruns for musicians.

• Roland JD-800 Review
• Roland JD-990 Review
• Keys, Synths & Samplers Forum
• KSS Roland JD-990/JD-800 competition

Polynominal JD-800 This guy have good tech specifications material and some JD800 stuff.


www.bluesynths.com A detailed guide to keyboards and their musical aspects by synth lovers. good stuff, very nice pictures and great sound demos (not the internals) of the JD-800!
They also have very interesting sound at their Myspace profile: Roland JD800 Long Mix.

SynthMania.com Information and Demos of Synthesizers. Great material or the Jd-990, sound demos for original and card patches . Must see and listen!



retrosound.de  Vintage Synthesizers Page.


synrise.de This site turned to pay mode, but have some o the best material about synths I have seen.



Don Solaris  A great musician and a JD-master with the JD-800 and JD-990. His site have some interesting and very usefull technical material.

Midiox Sysex utility program for sending/receiving bulk dumps from your synth (Win 9X.. and later.

Pro-Rec's JD-800 & jd-990 page  3rd party patches for your JD-990.

Sonicstate.com  Great synth site!


MatrixSynth Great everything synths blog!



Sonic Plug- Roland JD-990 Great tribute page to the JD-990.


http://www.synthzone.com Great synth tech info.

• Synthzone JD800 patches some assorted patches  for the JD-800.
  
• Synthzone JD990 patches some assorted patches  for the JD-990.
  

MEMI-Makers-Soundpool Free JD-990 Sounds.

Kid Nepro's Home page 3rd party patch creator/reseller. Good stuff, I have their demo for the 990 in the file section.

Dancetech.com  Good review.

JarreLook  Great Jean Michel Jarre Tribute Band from the UK.
If you want Jarre patches, see their download page for JD800 patches and other synths




JD-800.tripod.com  - Good info and description of the JD-800 Sound Libraries cards and waveforms.


Mark Smart have great material:

• Mark Smart JD-800 page -Using the JD-800 As A Giant MIDI Slider Box 
• Mark Smart Choir Sounds Without Samples - Excelent page about about creating choir patches for the JD-800, based on the classic VP-330. Choir Patches and sound Demos avalilable.

Bobby Blues JD800/JD990 page A vintage 80's-90's synthesizers site with a good JD area with synthesis description, collection of patches, links to the comercial patch sites, some examples of famous artists, etc.



Synthony Music´s Synth & Amp; Midi Museum


Dragonkiller  Good japanese page with links for more stuff, movies, etc.


Sysex Database Sysex messages for the JD and other synths.

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