Wanted: Lowrey Organ Service Technician

You are not going to believe this. YESTERDAY I threw away all my old service manuals and schematics of the Lowrey Organs I used to service 30 - 40 years ago. I saved them for years thinking someone might need them. Then just yesterday I decided to throw them out. I am so sorry, but maybe if I remove some of the cobwebs from my worn-out memory I may be able to remember some valuable things to help you.

Richard

Yes I would, 'cuz every time I throw something out, next week or month somebody else needs it. My problem is not too technical. There is a pronounced hum when power is applied. That has to be caused by the dried out electrolytic capacitors in the power supply located under the foot pedal. But where to find such a thing these days is a big question mark. Every google search comes up with the wrong component. Anybody remember who bought out Sprague assets? Looking at the keys it appears this model has silver coated spring (wire>) switch contacts. The wires are very black but gentle rubbing soon brings up a shiny silver finish underneath. Okay, my question is; should I even think about cleaning these keyboard contacts. After all silver was used as a contact material because silver oxide is conductive. If I need to clean it; what cleaner is recommended. Any contact cleaner or something specific. Several of the keys produce an odd sound that does not fit into the music scale. Am I looking at major tone generator work or is dirty contacts more likely to be the cause. Until I find a source for those old electrolytic caps in aluminum cans I'm hooped since the loud hum is likely contributing to the odd sound. The volume control seems to work fine. I must confess I had never seen an optocoupler device used as an analog volume control before. Neat solution to getting crackles out of the volume circuit. It is a family heirloom and I'm contributing my time for free but I fear the cost of parts alone may exceed the cost of a brand new keyboard by a considerable amount. Local repair shops don't even want to look at it. Too costly they say. not worthwhile.

Elnav,

In answer to your question about Sprague, they were bought out by Vishay some time ago.

Vishay/Sprague

As far as the capacitors go, if they are indeed just power supply filtering, it will not be extremely important to find an exact match. Just be sure the voltage rating is at least as high as the original, and find the closest value you can, going to a higher value than the original would be better than going lower. I prefer to buy 105 degree C parts when ever I have to replace electrolytics, as opposed to the 85 degree ones, they have a longer useful life. Not sure of the best distributors in Canada, but in the states I would buy such parts from Digikey, Mouser, or Newark. They are not the cheapest, but they carry good brands, and a very wide selection. Good luck with your search and refurb job!

Tom

Thanks for that info. Is my concern regarding hum unfounded? From what I seem to recall, it was deemed important to have that shielded case around the capacitors as a way to eliminate picking up other electrical noise. At the moment I can only find a mix of radial and axial leaded components which would involve cobbling together a messy wire ball with flying leads that in theory could pick up noise. Being physically larger they would of necessity have to remain outside the grounded chassis enclosure.

Put the original power supply to one side and build a modern one without hum....I will do my best to help if you can give me voltage/current details.....

Can't really do that since the chassis of the power supply also forms the mounting frame for the foot pedals to control volume, not to mention some other sound effect. Brackets are spot welded into place. And the cable connector is an odd ball. There are three seperate ground wires brought down in the harness and soldered to a tab on the chassis. Six more wires go into chassis via the oddball connector. My average reading meter is unable to filter out the amount of AC ripple riding on top of the DC. It looks like a 21V output, so I guess the readings are distorted. Until I identify them and also learn the exact correct voltage, I'm in a holding pattern. If it was a 12V supply I already have such a thing. Will get back to you on the new power supply when I have solid data to go by. I could simply cut off the wires totally but then there is no going back. I do not have tooling or connectors to repair the chopped cable if I had to put it back. Not much in the way of extra mounting space.

I still need to hear back from the minister how far I should go expense wise. If the cost exceed $200 it would be cheaper to leave the furniture as an heirloom and plunk a modern Yamaha or Casio keyboard on top. I suspect part of the issue is the ministers wife is accustomed to this particular key layout and does not want to have to learn a different arangement of keys. Not to mention which the sound is not going to be exactly identical.

Does anyone know if these modern kayboards have foot controls that duplicate traditional organ style playing. Older people are sometimes resistant to change.

the power supply supplies various voltages needed for keying, gating, effects and that which is needed for the amplifier/amplification.

the hum is probably an A.C. hum and i suggest changing the larger can capacitors and the disc caps along the a.c. route.

there is a way to short the inputs of the pre-amps and amp to trace the noise, but i'd recommend changing the caps, (and the bridge rectifiers four diodes), first.

examine the smaller can caps also for the swell spot showing . . .

Arild,

In response to my earlier post about the caps, I'll confess, I've fixed a lot of electronics stuff, but organ is not on the list, yet. I have had to replace a dual capacitor with separate ones (in an older Tektronix oscilloscope), and I didn't see any issues with that. I had to do like you said, use axial leaded parts and stand them up next to each other, with mid-air connections and some pretty long lead lengths. One thing about 60 Hz or 120 Hz hum, it's not usually going to be a radiated noise moment, it's going to be conducted. So the shielding is going to be more important to keeping radiated noise from getting into the supply. I guess it will be trial and error. I did do a bit of searching yesterday, looking for dual caps. Looks like the only ones still available are higher voltage ones set up for some of the older tube type audio gear, nothing in the sub-100V range that I could find. There may be some new-old stock out there if your lucky enough to find it, but I'm not sure I'd be willing to take a chance on electrolytic caps that have been sitting around that long. They would certainly have to be re-formed if you did consider going that route.

If you do run into trouble with noise getting picked up from the filter cap setup, you could try some ferrite beads on the leads, or use some smaller value caps in parallel with the new electrolytics to kill the higher frequency stuff.

Looks like you have at least one expert joining in here, so I think you're on your way to knocking this one out. Good luck with the project, hope you'll be rewarded with some sweet sounds soon.

Tom

Hi Elnav,

Truly not trying to be a smart-arse here, but when I read your request, I Googled (if Google were soft and pretty, I'd marry it ) Lowery Tech Manuals, and this was the first hit ...

http://www.organservice.com/lowrey/LowreyManuals.htm

It SEEMS like they have about everything.

I used to provide loudspeaker products for Lowery a 'hundred years ago', but haven't heard much for a long, LONG time.

I hope this can help.

Kind regards ...

Wouldn't you know it. The electrolytics are gone judging by the loud hum and electrolytics is one of the pages not found when I click on the parts list. Locally the young guys in the parts departmens weren't even born when this organ was made. In fact most of them weren't even born when Sprague disappeared as a company.

Hi,

Try searching for 'vintage' parts ... there were a lot of hits. Many folks build and re-build vintage electronics, so there is a wealth of parts available ... just the search can be laborious.

Good luck, and kind regards ...

http://www.google.com/products?hl=en&rls=com.microsoft:*&newwindow=1&q=vintage+sprague+electrolytic+capacitors&um=1&ie=UTF-8&ei=mX7ASZjEMpyu6gOez4W4DQ&sa=X&oi=product_result_group&resnum=1&ct=title

I hope that for some reason I am not totally off base, but why are you having problems replacing these caps with modern equivalents? Is it a physical problem?

Modern caps are generally smaller for the same values/voltage.....but other than that....

Perhaps you could clue me in as to why e having problems.....the manufacturer's name should be the least of your problems......a foto or two might help me further....

Andy, one of the things I remember from my days of vacuum tube amplifiers was the ( I think) fact that replacing one multi cap with several individual axial leaded capacitors did not give as good a common mode noise rejection. In other words I might not totally eliminate the hum only reduce it. Then I would not know if I had actually cured the problem or merely shifted it. Hence my quest for a tech with actual experience on that particular instrument. From what I remember most of the power supplies of that era was of a design called a "pi" filter with some additional bypass caps and ripple filters. The caps were built into one case to reduce ripple and hum. Essential for sound equipment but nice for other stuff. This organ instrument power supply has two cans.Not just one like I remember. One of them being negative common case and the other positive case. In this particular circuit one cap is 2000 uF and three being of 1000 uF value. Negative case. The other capacitor is positive case and onecap value is 1500 uF the other being 500uF. All voltage ratings is 35V DC. The positive case is a surprise to me. I only worked on sound equipment as a hobby. I built my first stereo system system from parts scrounged from the trash bin and 17 inch Admiral B&W TV when I was 15 years old. Lacking schematics I had a lot of trouble getting the components values right. But by picking over the junked chassis in a radio TV repair store; I eventually figuered out which tube related to what function and then copied the parts assemblies associated with each stage. But AC hum was always a problem. On a TV you got dark band creeping across the screen and with sound amplifiers By the time I finished school and was actually working in the electronics industry things had shifted to solid state components and we were working on digital circuits.

Thanks for the reply and info.

I still feel that there must be a repair method using modern caps.

But if not and this is the PS(?), then build in a modern power supply, a good one of course....I can help with an excellent design from Elektor, in a pdf, that you can adjust from 5 to 40 volts at 10 amps, its switched mode and was designed for a HiFi system......so no mains hum.....I use one on my CNC........simple to build and very HiFi...!!

Andy you are probably right. But there are no parts available locally. Anything I need, will have to be ordered and shipped from Vancouver about 700 miles away. Remember I live out in nowhere in the middle of British Columbia's northern forests. Except for broken down welders there is nothing in the way of electronic equipment out here from which I could salvage stuff to cobble with. When I order something it had better be close to being exactly what I need. Shipping and handling will likely cost more than the parts. themselves.

there are atleast two more Lowry tech's on this board, i always wondered were we would end up . . .

the key contacts are self cleaning but i've used an alcohol swab in the past.

Pure might actually have some manuals when he gets here.

i get mine from a guy that bought out Hammond Organ stock before they went to Yamaha

I recently restored one of those organs. I can get the manual photocpied for you, but need the model number to make sure they are the same, or equivalent. The manual has schematics, but absolutely no service, parts, or maintenance information. I used commercial contact cleaner on all the spring contacts. The cleaner consists of 2 fluids, one for cleaning, and one for maintenance. It worked okay. Modern electrolytic capacitors are much better than the originals. You can find them at Digi-Key, Newark, etc. Since the hum is likely coming from the 110 volt supply, you probably want a 250 volt capacitor of about the same capacity as the original. No need to make it an exact match. Just maintain the proper polarity.

The capacitors are actually rated 35V. On either side of the power supply there are two power transistors Half the size of a typical TO-3 case. I guess this instrument was one of the transition era designs that bridged the technology concept from vacuum tubes to total solid state. In addition to the power transformer and cap cases; this chassis is also home to the volume control foot pedal. I guess the weight of the heavy chassis helped stabilize the foot pedal mechanism. The volume control consist of a black plastic tube with a instrument panel bulb in one end and a cadmium photo cell in the other. The foot pedal moves an arm to which a strip of photographic negative is fastened. This negative is a continuous gradient gray scale clear at one end and black at the other. Apart from the DC supply for the audio amps I expect the DC supply to the light bulb also has to be very stable and ripple free. Any ripple would produce a tremolo effect - would it not? The organ works - sort of. The sound is distorted with a tremolo effect or warble and the keys don't seem to produce a clean musical scale as you move up the scale. Some keys definitely produce an off key tone. the sustain switch does produce the correct sustain effect. I haven't got the time to dismantle and reverse engineer the whole instrument. I still work for a living. Hence my quest for tech tips from retired service techs.

The tremolo effect is maybe a revolving loudspeaker funnel, many organs had such a device....my ex had such an organ, it sounded fantastic, I paid 200 pounds sterling for it!! From a church.....I wonder what its worth today.....?

Not on this one. Speaker is fixed. I removed all electronics. I only mentioned what the effect sounded like This is a small 44 key X 2 switch rows organ.

less than 200 pounds sterling i'd expect . . .

I'm guessing, but I suspect its worth a hell of a lot more as it was all original and in a 100% working condition......if its still in that condition......it will be worth far more...

what is the make and model#, on the data plate located either under the lower manual, (on your knees looking up), or on the back of the organ?

do not clean the self burnishing key contacts . . .

I do not have that information. I will have to go back and check. The organ is at the ministers house not mine. I do not have any space to work so we left it where there is more room. Thanks for the tip about the self burnishing contacts. I had a feeling they might pose a delicate issue.

Sorry I didn't get back to you sooner, Been extremely busy. I may have the filters you need. I will search and if I find them I will test them under a load and if good will send them to you. I am going to send you a message with my e-mail and mailing address. If I find that I have anything that will help you, then you can send me your shipping address and I will ship it to you at my expense (I have a soft spot in my heart for underpaid ministers.)

Lowrey had self-cleaning contacts at that time. If the organ has sat unused for a time, the contacts become corroded. Active use will restore the contacts. If they are really bad, I use Freon TF (Very costly but effective). There were many non-polarized Electrolytics in that organ. They tend to open easily. If you can't find the exact replacement, Use two double value with negative ends soldered together. (If the original is say 25microfarad, use two 50 microfarad capacitors in series, common negative. Keying diodes can become leaky, I don't remember if that particular model used germanium or silicon. After you solve the hum from the power supply, check the rows and rows of diodes with a good VOM. Replace any leaky ones. I have tons of diodes that will work great even though they are not original. During that era, the normal tolerance was 20% on most components. You need only be concerned with tight tolerance on components in the waveshaping circuits and tone generators. There are 12 tone generators. After getting the other problems solved you will want to tune the instrument. There are adjustment pots on each of the 12 tone generators. If an in-tune piano is close by, use it. Otherwise any instrument that can produce the 12 basic notes will do.

The "A" note is created by a colpits oscillator circuit to produce a 440 hz tone. Each lower octave is produced by an eccles-jordan divider circuit to halve the note. That is: One octave down = 220 hz, two octaves down = 110 hz, 3 octaves 55 hz.

The upper octaves are acheived by a frequency doubler circuit. 1 octave up = 880 hz, 2 octaves = 1760 hz, 3 octaves - 3520 hz.

These are very straight forward simple circuits with common components. If you tune one key, say "C" All "C" notes will be tuned. So you see tuning is really easy.

If I think of something else, I'll throw you a note.

Richard

Thank you Richard. We are rehearsing fro the easter play this evening. I will try and get the model number of the organ at that time.

Good point about leaky diodes. Gee I had forgotten about that.

But now I am reminded of how often I had to check a few dozen diodes in a matrix. These days we take so much for granted that had to be laboriously tested out in the good 'ole days.

The organ did sit unused for a long while; hence my concern. Maybe I can get my cat to exercise the keys. Get her to walk up and down the keyboard for a while.

I pulled out the complete electronic boards assembly as a unit since they all sat on one frame. Had a good look but did not see anything obvious. Boards are clean, not very dusty and shows no sign of corrosion from excess moisture. The wooden core of the keys do not show any sign of swelling due to moisture absorption.

The suspect capacitors are polarized in aluminum cans mounted down on the power supply. The chassis that also forms the mounting for the foot pedals.

One can is common negative with a 2000 uf and three are 1000 uf value. Rated for 35VDC

The smaller can is a dual unit. 1500 uf and 500 UF also 35V but the can is common positive.

regards

Arild

If memory serves correctly the model you have was made in 1977 and we called it the L10 Model. It was known by the salesmen as a Teenie Genie. I checked my stock of Electrolytics and found none that will serve your purpose. Replacing the cans with exact replacements appears to be nearly impossible. You can easily replace the caps with tubular Electrolytics. The current ones are only a fraction of the size of the originals. You may need to mount them outside the power supply chassis. Keep the leads as short as possible and close to the metal chassis to minimize stray inductance. Check out this link: http://www.radioshack.com/search/index.jsp?kwCatId=&kw=electrolytic&origkw=electrolytic&sr=1 If the prices here are outside the range he is able to pay, let me know and maybe I can help. Richard