Opus 20

[don60]

Johannus can and will provide factory support for a 20-year-old Opus 20. They might not be as quick to provide it to individual owners (whatever their reported skill level in electronics) as they are to their own technicians whom they know and work with on a regular basis.

AA, your instrument should use 9700 series technology based on its build date, but your description of multiplexer chips sounds more like the precursor 9500. If you could post a photo of the processor area, I could tell you which you have. Some smaller instruments may have been built with 9500 even after the introduction of the newer series in the larger organs.

You could also look at the processor board (yes, I know it's partly hidden!) and find the JHO number--that will tell the tale as well. A serial number on the instrument would be nice too.

It would be a shame to give up on it over the keying problem until we have exhausted some simple possibilities.

Technical and parts support for Johannus in the US is provided through their technicians and dealers and always has been. We in turn have worked under different models including the Texas-based distributorship (which was recently ended) and direct contact with the factory. At this time, all parts and data come directly from the Netherlands. I have found my contact at the factory to be very fast and helpful in answering inquiries. Parts come by DHL in a couple of days.

AA, I doubt that anyone at Johannus is impugning your electronics skills--they simply priortize support for their own technicians since they have long working relationships with them and know their backgrounds. Stepping a customer through basic troubleshooting steps is not efficient when a knowledgeable technician might be able to zero in on the problem very quickly.

Please post the above information and I will try to help you salvage your Opus.

[AllenAnalog]

Thank you Don for that helpful information. My comments are totally based on multiple telephone conversations with Tom Britanyak. I have never tried to contact Johannus directly. I figured since he created this instrument he would be the source of the best information available. He seemed particularly upset when his direct factory contact was cut off when the Texas distributorship was established. Since he commissioned Johannus to build these Britson branded instruments I was rather astounded that they would do that to him.

I'll also add that Tom had me pull the ribbon connectors, one at a time, for the manuals, pedals and stopboard to make sure that one of those was not pulling down one of the 16 data lines. That made no difference when the organ was missing every 8th item.

All chips were carefully checked for bent pins (none) and proper orientation when they were moved around. IDC connectors were checked to see if there were any obvious issues and none were found. Voltage was checked at the terminals on the processor board multiple times.

The nameplate of the organ has the following information: OPUS OEM38; S/N 122 46 96 8421

Here is the data from the processor board:

Board label: Master Processor; mh/sd/sd/kb; JHO9100

So I'm guessing this is 9100 series technology and perhaps older than Tom thought it was.

There is a large DIP chip with the label OPUS20.

There is a small chip with the label Britson Master; OEM38.902i; C/S 898D

Here is a photograph of the processor board.

[don60]

Could one of the moderators move this Opus 20 discussion to a new thread so that AA and I can confer more effectively?

AA,
The board in your photo is the master processor used in 9500 technology organs. A small rack contains an additional slave processor board that communicates with the master using high-speed MIDI signaling.

The repetitive keying problem that you describe is definitely a fault in one of the 8255 expander chips, specifically U14 closest to the main power supply connector. Prior to your moving around and replacing the chips, you should also have noticed that one step on the transposer was flawed--the same scanning signal is used in the transposer switch.

My limited experience with these 8255 chips is that they are extremely static sensitive--one organ I worked on had two or three bad from an apparent electrical surge or diffuse lightning strike, including one that was intermittent. (This organ had the same keying defect as yours, incidentally.) Be very certain that the parts you have on the board at the moment really are good. Replacements are not critical regarding speed rating and the like--I used two different versions bought from eBay and Mouser with no problems. The fact that the replacement chips did not work makes me think that another problem developed during the replacement process.

What exactly do you mean by saying that the organ is dead now? I presume you have no sound from any of the stops. Do the stop lamps light in response to manual or preset registration changes? Have you verified +5 V right at the master processor board?

The slave processor actually uses a separate rack power supply that could have failed. If it has, the user controls will still appear active (stop lamps working, etc.), but you will have no sound production.

A cracked trace on the master processor is always a possibility, but these boards are fairly robust. I have never damaged one mechanically despite some rather serious manhandling. A more likely problem is a dead component from a static hit.

You were on the right track initially by focusing on the expander chips. You might be one more dead component away from having a nice little organ. Johannus sound quality has improved greatly since it was built, but the Britson improvements ought to make it quite acceptable. I am happy to keep consulting on it if you are willing to do a little more work.

[AllenAnalog]

I appreciate your guidance Don. I'll get back into the instrument as soon as I have some time. Right now I'm dealing with a sudden and unexpected serious medical problem that has diverted my focus to getting my personal affairs in order.

[davidecasteel]

AA, I am concerned about your last post. Are you experiencing serious medical issues? I pray for quick resolution.

David

[AllenAnalog]

Thank you for your concern David. I went to the ER with what was first thought to be a gall bladder attack that turned out to be a pulmonary embolism. Both the doctors and I were shocked at this diagnosis since I am in what I thought was rather good health. So here I am helping pay for those evening news TV adds for Xaralto. One of those moments at the pharmacy counter where you ask yourself "how much is your life worth?"

My dad died of a PE, at age 62, after surgery back in 1971 just as he was planning his retirement. And here I am planning mine when this happened. It hits you hard. But with the new drugs around today (I start a statin tomorrow) I'm maintaining a positive outlook and still hoping to have my big music room by the end of next year. With the help of Don and others on here the Britson may be part of that. But for the next week or so I still have medical tests and work on my legal documents so I have peace of mind about having everything in order.

Nothing like a big slap upside your head (or lungs) to clarify your thinking and priorities.

[AllenAnalog]

I finally had time to get back to the Britson/Johannus today. The last time I worked on it, the organ was totally dead on power-up. I had pulled the processor board out to take the photo I posted last year so while I had it out I removed the replacement chips (TMP82C55 multiplexer and EF68B50 async interface) I had tried and put back all of the original chips - in totally random order for each set.

Both sets of these chips (6 multiplexer, 4 async) had been moved around - first with all originals and then with one or two replacements in the mix. So any issues of pins not making contact in sockets should have been overcome during these moves.

With great trepidation (and no expectations for a different result) to my great surprise the organ came to life when I turned on the power! So, just as I had done several times before, I performed the restore-to-defaults reset and cleared the piston memory.

Results:

• The original problem of every 8^th note, piston, etc. missing is now fixed.
• The MIDI In works; I haven't tried the Out yet.
• Piston memory works.
• All special function pistons (bass coupler, etc.) work.
• Transposer works on all positions.
• All stop controls work properly except for the Strings tab in the Special Voices section.This is a new problem.The light flashes when you push the tab.Sometimes the stop goes on (but not the light) but most of the time it does not. It has the same problem turning it off once it is on.

Of course all of this begs the question of what fixed the main problem? I'm concerned it could happen again. Is there a faulty chip in a new position where its function is slightly different? Any thoughts on whether it was one of the mux chips or one of the async chips?

It would certainly be helpful to know the specific functions of each of those ten chips so if my problem crops up again I would know which chip location is suspect.

For now the instrument is saved from the recycling facility. Any insight into fixing my remaining problem would be appreciated.

[don60]

AA, I can send you the schematics for your organ, or a similar one, if you PM me a good email address. You will have to spend some time studying the drawings and tracing signals from one sheet to another to get the gist of the multiplexing scheme. The short overview is that all user controls including keys and pistons are multiplexed and enter the system on this processor board through the expander chips. A fault in any one of them ought to show up rather prominently unless the bad chip serves a little-used purpose that you have not investigated.

A more likely explanation for the failure is that you had some oxidation or dirt in a socket that was scrubbed away from all of the chip-swapping. The socket contacts tend to embrittle and take a set after a while, so they do not grip as tightly on the chip legs as they should. I fixed (at least for now) a similar instrument over the summer that had random ciphers and all sorts of other issues just be removing each chip, spraying contacts with Deoxit, and reseating them. (Mostly one does not have to remove the chips entirely, just pry them out slightly so the Deoxit will penetrate and the chips can be "rocked" into place.) As I pried the chips out, the legs made a rather loud creaking sound, like very old metal scraping lightly on very old metal. The sound largely vanished after exercising the contacts, so I attribute it to the metallurgical issues mentioned above.

The one quirky stop tab probably has a bad rubber contact or a little bit of conductive dirt trapped inside. It is almost impossible for an electronic fault in the processor to produce the symptoms you describe. Be sure that nothing else is stuck on, though, since a competing input signal might be upsetting this one. This advice is particularly important for controls such as reversible couplers where a stuck thumb or toe piston can override the stop tab.

I am pleased that you have brought the beast back to life. The chances of a broken trace on the processor are now very low given what you report. Focus on IC sockets and pins and possibly a defective chip.

[jbird604]

Yay! Glad it's working now. I wish I could say the same for the Britson we saved from the landfill here a few years back. It has been in my associate tech's house since we got it, and he has spent a lot of hours working it over. We feel the problems are related to the power supply lines, and he can sometimes get it to work almost perfectly for a while after he pokes around inside and pushes down on all the power plugs everywhere. Then it will act up again before long. He is quite frustrated but perhaps he just hasn't hit the right spots yet.

I do know that when that organ is working, it has a very lovely sound. I'd almost say that it sounds better than my Allen in some ways. I know it's more pleasant to play with headphones than my Allen is (Allen organs being, to me, particularly unsuited to headphone playing for whatever reasons).

Anyway, here's hoping you've squashed the bug. Keep up the good work and I may have a business for you to buy out one of these days!

[don60]

John, if your Brohannus uses a 9700 series processor board with the infamous yellow connector for the power supply, you should remove the plug and solder the green and gray +5V/gnd wires directly to the socket pins. (This process takes a steady hand and a little shrink tubing for insulation.) These connectors are known weaknesses, and the factory recommends this improvement. The current drawn from the 5V supply is substantial and will quickly cause an intermittent at the connector if the pins are failing.

The +/- 12V supply connector almost never seems to cause trouble because the current is much lower.

[jbird604]

Thanks for that note, Don. I think he has done at least some of the connectors already. But I'll pass along that word of advice. It would be great if we could finally make this little organ stable.

[don60]

And sometimes the insulation displacement (punchdown) connections between the wires and the connectors will start to fail. I always solder them.

[AllenAnalog]

Thanks Don. I'll send a PM to you. I just tested the MIDI Out with my synth and it works. So now everything except the strings stop checks out. While I have the back open I'll solder the wires on that power connector for the processor board too.

This instrument is based on the Opus 20 but has the single piston rail of an Opus 5 and is missing the + and - pistons, the PGM piston and the 7-segment display shown in the Opus 20 manual. So I can't program the MIDI as outlined in the manual. I do see a connector on the processor board for the display so I presume it was an option that Tom B did not spec.

I can't say that I find the sound of the "Brohannus" (is that a portmanteau?) that impressive but I've never really heard it through the remote speakers, only the console speakers. The chimes, strings, harpsichord and gospel special voices are rather interesting and fairly good but the vibrato on the gospel stop is gross. Way too fast and fluttery. I've not tried listening with headphones so I guess I should do that.

The bass and melody (cantus firmus) couplers actually work rather well. Since this instrument is microprocessor based, I would expect that the BC function would work much better than the afterthought BC board I will eventually try on my Allen ADC-5300.

[don60]

The console speakers on older Johanni are rather crappy. Try it with some external cabinets.