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Thread: Conn Rhapsody 628 crackling noise

  1. #1

    Conn Rhapsody 628 crackling noise

    Non musician, electrical dyslexic, stupid newbie here. So please bear with me...

    My wife has a Conn Rhapsody 628 which she had given to her by a church when they replaced it with something more up to date. It has a crackling noise that is inconsistant but more prevelent on the lower keyboard than the upper. Volume does not seem to effect it and it does not effect the pedals.

    My wife is beginning to practice more since she will now be occassionally filling in at the church that gave her the organ. The crackling is really annoying to her and she says it makes it difficult to concentrate when she practices.

    Any ideas what could cause this? Any good places to start? Any chance it could just involve some contact cleaning?

    I'm not completely inept--I used to restore European motorcycles and before that spent much time working on race cars--but this stuff is totally foriegn to me. Electronics is just magic. Any suggestions?

    Thanks,

    Kip

  2. #2
    Senior Member indianajo's Avatar
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    I had a faint crackling/frying pan noise in my ST120 power amp after I repaired it the first time. The second time I replaced the input 5 uf (microfarad) tantalum capacitor, with ceramic this time, it totally went away. Electrolytic capacitors get old in 20 years for high quality ones with great seals, 1 year for cheapos. Usually they just go low value and stop passing low frequencies, but sometimes the big ones in the power supply can short and explode. If your organ is transistorized and has no voltages over 24, you can take off your jewelry and start replacing, but if it has tubes or any voltage over 24, read aikenamps.com technical resources button technician safety button about not electrocuting yourself before touching anything metal. My first replacement tantalum cap with the crackle was bought off the bargain table in front of the supply house. I believe the analog these days where you buy outdated caps is E-bay. I suggest you buy any caps from a first line dealer like newark.com or mouser.com in the US. A WP25 iron with a chisel (not pointed) tip is fairly useful, as is scrap wire with flux on it to wick up the old solder. Wear safety glasses, solder can splash. Electrolytic caps look like aluminum cans with etched writing, or plastic or cardboard sleeves with a plus on one end or a minus on the other. Tantalum electrolytics look like peanut M&M's. Any value under 10 uf and 50 WV can be replaced by forever film caps or ceramic caps nowadays. Replacement electrolytics should be same to 40% higher in value, and same to 40% higher in working voltage (WVDC) Make sure you mark the PCB (printed circuit board) with the plus before you remove, as if you install them backwards they boil and explode. Timing electrolytics should be exactly the same value. You can detect timing caps, they usually have a tolerance of +- 20% or 10%, whereas the run of the mill hum bucking electrolytic is +80%-20%.
    Contact cleaning cant hurt, except for the fire hazard. Don't unplug anything with the power on. Modern contact cleaners are gasoline with a fancy name in a spray can. No smoking, no open flame heaters lights or pilots within 30', no electricity turned on and off, use a fan. Some people here like expensive Caig Deoxit for tabs and keys, but I found lumber yard stuff fixed my problems.
    A useful beginner book on solid state electronics and meter use for debugging is "Electronic Devices, Electron Flow Version" by Thomas L. Floyd, Prentice Hall, ISBN 0-13-363599-6. I got mine at Goodwill because the problems are obsolete. Your community college bookstore might have something just as good. Understanding capacitor and inductor filter and tuned circuits is interesting, wikipedia is very cheap. I started learning electronics with the Ford car manual and a dead car radio- the tube voltage warning was missing, and I learned about 440V in a 6v car radio the hard way.
    Last edited by indianajo; 11-20-2010 at 10:51 AM.
    city Hammond H-182 organ (2 ea),A100,10-82 TC,Steinway 40" console piano, Sohmer 39" piano, Ensoniq EPS, Wurlitzer 4500, Dynakit ST120, ST70 amps, Herald Ra88 Mixer, Peavey SP2XT speakers,BIC turntable; country Hammond H112.

  3. #3

    Indianajo,

    Thanks for the reply. Searching the forum I found a guy that might have a source for a service manual. I will get with him and see if I can score one of those.

    If I am reading your post correctly, your suspician is that I am dealing with failing capacitors in the power supply. Short of (electrical pun there...) testing and replacing all the capacitors, is there any reliable source for rebuilt/refurbished power supplies?

    My father, who is 87, is an old time ham radio guy (since the 1930s) and when in his prime this would be a no sweat job for him. His hands shake and his eyesite is failing now.

    Thanks again for the info. I'm in the knowledge collection stage right now. Chris needs to practice for upcoming Christmas programs so I wont be attacking this until after Christmas.

    Ciao,

    Kip

  4. #4
    Senior Member indianajo's Avatar
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    [QUOTE=Offcamber1;220602
    If I am reading your post correctly, your suspician is that I am dealing with failing capacitors in the power supply. Short of (electrical pun there...) testing and replacing all the capacitors, is there any reliable source for rebuilt/refurbished power supplies?
    [/QUOTE]
    Crackling more probably comes from an interstage coupling capacitor between one transistor circuit and another. On the other hand Conn has been bankrupt since 196?. 2010-1969=41 years. Every electrolytic cap in the organ is weak. Do them all or do none, no time wasted debugging. My H182 had 70 caps, high for a Hammond. 4 were FP can caps that are $33 each. (sole source) This an exclusively tube design cap. Those 4 caps quadrupled the volume of my organ. 3 made the pedal "string bass" feature work, and 63 made it sound better with more bass and more high. I didn't do the 110 electrolytics in the "harp" feature, they are a weird size and $6 each. When replacing caps or any parts, do two at a time and check that the organ works still, less you install a mistake you can't find later, or a part that is not quite an exact match and it causes something weird to happen. I made a few cold solder joints, that would have been hard to find had I not done it that way.
    On the other hand buy your caps $40 at a time, to save on the $6 shipping charges. Make a list. Buy 2000 hour up rated caps, the seals are better than the cheap ones. Newark has the hour rating in the selection chart.
    1965-1970 Hammonds are worth so much, because they have way fewer electrolytic caps than other models. Pre 65, they had 120 paper dielectric caps that need to be replaced if the organ sounds weird. Post 1980 organs have proprietary IC's that, if there is a problem, can't be bought anymore. If you have any idea of upgrading, do it now before you do the work. How many pedals do you have? under 25, it is hard to do church work in any key. Try to get the number of pedals that she uses at church. Some theater Conn's are still desirable because of the number of sounds, but if it is an entry level organ with 13 pedals I would get a $100 Hammond M, L, T, (13 pedals) or a $500 E or H 300 (25 pedals). I'm slobbering over a E300 in Owensboro, KY, and an H395 in Bowling Green, KY, this weekend for $500 and $700 asking price. Then again, an early Allen C3 went here for free on craigslist, must move today. Roger and Allen are desirable of any age, they are still in business. However, watch buying Roger and Allen consoles, they don't make sound.
    Last edited by indianajo; 11-20-2010 at 04:30 PM.
    city Hammond H-182 organ (2 ea),A100,10-82 TC,Steinway 40" console piano, Sohmer 39" piano, Ensoniq EPS, Wurlitzer 4500, Dynakit ST120, ST70 amps, Herald Ra88 Mixer, Peavey SP2XT speakers,BIC turntable; country Hammond H112.

  5. #5

    This particular Conn 628 has a 25 pedal pedalboard. The one she will play in chuch tomorrow is a 2 manuel Allen Protege, also with 25 pedals. The one she takes her lessons on is a 4 manuel Johannas (might have the spelling wrong), with 4700 stops or something like that; it is truly spectacular.

    I get the two capacitor at a time thing. When racing cars one never makes more than one or two changes at a time as it is easy to lose your way.

    I'm going to let her get through the holidays, then pull the power supply and take a look.

    My wife is in the Wabash Valley AGO, we're close to Terre Haute. If you go to Owensboro, leave enough time to go to eat at Colby's on the square downtown. Great food...

    Thanks for your help and suggestions.

    Kip

  6. #6
    Senior Member indianajo's Avatar
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    Sounds as if your organ is possibly worth keeping. I'm having trouble getting a member of SIAGO to teach me voicing on a 25 pedal organ, they all have 32 pedal jobs that I would never be able to afford or find one I could practice on. The Indiana AGO convener Dr Lamb would come to my house the days he visits his family in Louisville. I might be able to clean house well enough some day. Then there is that squeal in the power amp I put in the organ trying to fix the reverb- one of my many indoor projects lined up for winter. I took the reverb tube socket out, and the new one requires machine work to make a grounding/mounting ring before I can get it back in.
    If you want to drool a bit, this is the link to the H395 in Bowling Green http://bgky.craigslist.org/msg/2061958533.html It was Hammond's most classical sounding model. I have a predecessor H182 that I love the sound of, but the volume knocks the power amp and preamp tubes out of the socket, they need rocking a lot. I think I can build a solid state 5 input mixer/pop filter/percussion, and a 3 channel 40 W/channel amp a lot cheaper than $700, however. The H395 is solid state and hence worth $500 more than mine. Both H's have classical preset sounds more like a pipe organ than the gritty sounds of the A/B/C/D that are so popular in seventies rock music.
    This is the link to the Hammond E133 in New Harmony, IN, http://nashville.craigslist.org/msg/2068923715.html I don't know why they only advertise it in Nashville. The E is one grade below the H, the bottom octave of the pedal is divided down instead of made from real 16' rotors like the H is. It doesn't have the tenth and eleventh overtone rotors like the H, and fewer percussion tabs. (Percussion is Hammond speak for what my band director called the "attack", organ tuners call it the "chiff") I don't think E's have slow vibrato, or "celeste" in organspeak, like the H does. I love celeste+reverb on classical music,it sounds a little like a stone cathedral must sound.
    Have fun with Christmas music.
    Last edited by indianajo; 11-21-2010 at 02:41 AM.
    city Hammond H-182 organ (2 ea),A100,10-82 TC,Steinway 40" console piano, Sohmer 39" piano, Ensoniq EPS, Wurlitzer 4500, Dynakit ST120, ST70 amps, Herald Ra88 Mixer, Peavey SP2XT speakers,BIC turntable; country Hammond H112.

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