Results 1 to 10 of 10

Thread: Wurlitzer 4500 troubleshooting issue, need advice from expert.

  1. #1
    Senior Member paulj0557's Avatar
    Join Date
    Oct 2010
    Posts
    1,502


    Wurlitzer 4500 troubleshooting issue, need advice from expert.

    Alright I was just bragging on my 4500 a half an hour ago because it needed nothing since getting it except playing and adjusting a couple contacts. Have had the organ a few months, but have only been able to fiddle around with it without pedals until last week when I could finally put the organ where I wanted it and install the pedal board. When I installed the pedal board all of the notes worked except the highest 4 notes and the G below middle C. Now

    Now one peculiarity was the fact that the D above middle C on the pedal board sometimes was a D, but usually the adjacent C or E.

    Here is my issue:

    15-20 minutes ago I was playing it and all of the D's suddenly quit. I turned off the organ, then back on and the D's were back ( transistor reset?). Played a minute and they are out again. Then again. The 4th time I decided to only play only the keyboard manuals and not the bass pedals. The D didn't seem to go out...I say seem because after a few minutes I decided to play the pedals again. No sooner than I did this the entire organ lost all audio. What happened? Are there fuses in the organ related to this issue. I have no schematics, but can locate the place where the problem is explained to me to look at fairly easily due to Wurlitzer's excellent sub-chassis lay-out.

    I love this 4500! It blows away all of my other organs really, and it was a freebie. Beautiful cabinet. A real beast.

    There are many fuses where the crossover network is for the 8 factory speakers on the organ, but I really don't know where any other fuses are. BTW the power is on- lights, spectratone spinning. Just no audio.

    Help! I need my organ.

    My skill level is good, I have a scope, and meter. I can troubleshoot it myself even, I guess i am just asking in case someone has an obvious answer.

    Thank you, Paul
    BIG SCORE 5/9/14! FOUND $80 WURLITZER BRASS HORN IN CASE WITH STAND,LONG & SHORT BELL
    Wurlitzer '46' Model 31 Orgatron & 310 rotary cab, 56' 4410 , 65' 4300
    Hammond '55' S6 Chord Organ,HR-40,ER-20, Altec A-7(SOLD but missed). '6?-7?' X66 & 12-77 tone cabinet & L112 spinet [latest addition to my collection]...my RT2,Elegante,Leslie 31H sold
    Gulbransen 61' 1132 '76' Rialto II & Leslie 705 + two 540
    Conn'68' 543 Minuet '57' 406 Caprice '59' 815 Classic (the 29th 815)

  2. #2
    Senior Member Jan Girardot's Avatar
    Join Date
    Jul 2007
    Posts
    1,192


    Hi, Paul;


    First of all, a question:is your WurliTzer a 4500, a 4500R, a 4502 or a 4520? If there is no audio on any channel, I would first check the earphone jack. On most 4500's there is a multiple-contact in the jack, since that model has multiple audio channels. Try plugging and unplugging a 1/4" earphone plug into that jack and see if the audio comes back.

  3. #3
    Senior Member paulj0557's Avatar
    Join Date
    Oct 2010
    Posts
    1,502


    Like I said, it's a 4500 period.


    It has audio, I actually popped it open ( Wurlitzer's are easy to open and get at everything. So I touched around up where the various tabs are and flipped all of the speaker configuration tabs and there is audio at all speakers from body capacitance. No headphone on a 4500. I forgot that each of the two amp chassis have removable fuses on the chassis. The lower chassis ( not the one above the pedal, but the other one) has a blown fuse. This chassis also handles the two multi-pin round plugs for the pedals. I removed the chassis to look for visible problems. It looks good. Wurlitzer's QC was terrific! No wonder these 45 year old solid state Wurlitzer organs still work.

    So the obvious is ruled out. I've unhooked the pedals and am considering throwing another fuse in there. I'll probably re-install the chassis upside down if I do though ( with plugs in right spots obviously) so I can test it with the scope. There seems to be no physical reason why the D pedal note above middle C would be sounding a different note while both keyboards were fine and the other D on the pedals was also fine.

    Does someone understand the divider arrangement for the pedals? I'm assuming it is the board mounted inside the front kick panel with the neon lights on it, correct? BTW, the reason those upper notes and the G below middle C on the pedals don't work is because of faulty magnetic reed switches on the pedal board itself ( easy repair if I get new switches), chances are very good the circuity for these notes is good. So look at it like the organ was 100% functional with the former info I gave, the D's on the manuals quit, turned off organ & D's worked again while not playing pedals for a moment, but then when the working D on the pedals was played withthe manual's D's the D's went out. Then I turned off organ, turned it back on- the D's worked again for a 45 seconds-minute...thought " alright, now let's play the pedals" then NOTHING ( this is when that fuse blew). So why did it blow? That is the question.

    Any answers?
    BIG SCORE 5/9/14! FOUND $80 WURLITZER BRASS HORN IN CASE WITH STAND,LONG & SHORT BELL
    Wurlitzer '46' Model 31 Orgatron & 310 rotary cab, 56' 4410 , 65' 4300
    Hammond '55' S6 Chord Organ,HR-40,ER-20, Altec A-7(SOLD but missed). '6?-7?' X66 & 12-77 tone cabinet & L112 spinet [latest addition to my collection]...my RT2,Elegante,Leslie 31H sold
    Gulbransen 61' 1132 '76' Rialto II & Leslie 705 + two 540
    Conn'68' 543 Minuet '57' 406 Caprice '59' 815 Classic (the 29th 815)

  4. #4
    Senior Member paulj0557's Avatar
    Join Date
    Oct 2010
    Posts
    1,502


    Since we're on the subject of 4500's etc, what is a 4500 looking organ that has rocker tabs over on the upper right cheek block? What are those tabs for and what model is it. I've seen a few pictures of these organs, but I can't make out what those tabs are. Also, I've been told that the 4500 and the 4520 are the same organ, just different cabinets ( yes, I know the 4520 is the theater horseshoe...) and I believe it since the tabs all cross reference while looking at both organs. It appears that the 4500 was around for 2 years before the 4520 so did they change anything in those two years?
    I would love it if someone could upload a schematic of a 4500 to photobucket and copy the image link to here ( like I did with the image in this reply), it's free and it's easy. As far as copyright boloney, look have you seen how many free guitar amp schematics are floating around the web? How many guitar effects pedals etc.? What's it going to hurt anyone to post a few organ schematics? I would appreciate it greatly. If not then as soon as I can afford it I will get a set from Morelock's myself and post them.

    Appreciate any help, Thanks- Paul
    BIG SCORE 5/9/14! FOUND $80 WURLITZER BRASS HORN IN CASE WITH STAND,LONG & SHORT BELL
    Wurlitzer '46' Model 31 Orgatron & 310 rotary cab, 56' 4410 , 65' 4300
    Hammond '55' S6 Chord Organ,HR-40,ER-20, Altec A-7(SOLD but missed). '6?-7?' X66 & 12-77 tone cabinet & L112 spinet [latest addition to my collection]...my RT2,Elegante,Leslie 31H sold
    Gulbransen 61' 1132 '76' Rialto II & Leslie 705 + two 540
    Conn'68' 543 Minuet '57' 406 Caprice '59' 815 Classic (the 29th 815)

  5. #5
    Member afuller5's Avatar
    Join Date
    Jul 2005
    Location
    Atlanta, GA
    Posts
    349


    Paul,

    I'm not in any way knowledgeable about electronics. However, I used to play a 4502 at church. We had a similar issue with all the Bs (except the highest) going out. After the organ tech came twice, he discovered that there was a transistor somewhere in the divider circuitry that was not working properly. He said that it was still working but was not working as it should in this particular application. It may have been out of spec. As I recall, he found the problem by gently wiggling the transistors, resistors, capacitors, etc. in the divider circuitry for the Bs. Your problem with the Ds could have a similar cause.

    I hope this may be of a little help.

    Allen
    Currently own: Roland Atelier AT-90, Yamaha 115D, Roland DP-90SE, Yamaha PSR-S910

  6. #6
    Senior Member paulj0557's Avatar
    Join Date
    Oct 2010
    Posts
    1,502


    Yes, good advice. This technique you suggested is what I used last January when I got the organ. It was cold out and I noticed that if I squeezed one of the transistors on the 'A notes' tone generator part or the circuit board ( Wurlitzer used 3 notes per board X 4 boards=12 notes) the note came back for a minute. When I brought the organ in from the cold garage the note was fine.

    After removing the chassis which is loaded with electrolytic capacitor cans I realized that ultimately if the fuse on this chassis blew that the problem could ultimately be in the fact that possible one of these capacitors is breaking down. It's a wild guess, but my knowledge of transistors is far less than tube electronics. I'm a bit confused because if the DC components located on the generator boards has trouble why would this blow a fuse. Wouldn't it be more likely that it has to do with the power supply components on this chassis that blew the fuse in the first place? So shouldn't I be looking on this chassis for the problem? Not much here except A.C. to D.C. conversion. Man I need schematics!
    BIG SCORE 5/9/14! FOUND $80 WURLITZER BRASS HORN IN CASE WITH STAND,LONG & SHORT BELL
    Wurlitzer '46' Model 31 Orgatron & 310 rotary cab, 56' 4410 , 65' 4300
    Hammond '55' S6 Chord Organ,HR-40,ER-20, Altec A-7(SOLD but missed). '6?-7?' X66 & 12-77 tone cabinet & L112 spinet [latest addition to my collection]...my RT2,Elegante,Leslie 31H sold
    Gulbransen 61' 1132 '76' Rialto II & Leslie 705 + two 540
    Conn'68' 543 Minuet '57' 406 Caprice '59' 815 Classic (the 29th 815)

  7. #7
    Senior Member indianajo's Avatar
    Join Date
    Dec 2009
    Location
    Jeffersonville, Indiana
    Posts
    4,402


    Electrolytic capacitors are water filled cans sealed with rubber. In 45 years the rubber goes bad, the water leaks out as they get warm. The other components don't deteriorate based on time, more on thermal cycles. I would replace every electrolytic if I liked the organ enough to spend the money an time. I put 70 electrolytics and $200 in my Hammond H100. I could have saved $140 by replacing the 4 FP cans $33 up with axial or radial lead caps under the deck on terminal strips. However, FP cans are one of the few products still made in USA, so I don't regret it a lot. The cans come from tubesandmore.com or triodeelectronics.com or tonewheelgeneral.com: different values are in stock at different suppliers. High voltage axial and radials caps are mostly at newark.com. Low voltage transistor electrolytics are cheap at mouser.com. In axial and radial lead caps, you have the option of buying 2000 hour up rated ones, which have better rubber seals than the 500 hour or unrated ones. Download the datasheet on the cap at mouser to get hours. Newark has the hours listed on the selector table. On N&M, click passive components, click capacitors, click aluminum electrolytic then select value and voltage. You can go up to 30% higher on value and 50% higher on voltage on caps that are not better tolerance (the original) than +-20%. The ones blowing the fuse are probably on the power supply, near the transformer. Measure these at 25 VDC or less before you touch the metal to change them, if not discharge them through a resistor and some clip leads with rubber boots (R**** S*****). Don't replace caps that don't have a plus on one end, or a minus on the other end. Mark the plus on the PCB with a sharpie before removal, if you get it backwards they explode. In values of 2 uf or up there are some "NP" electrolytic caps that are rare, but non-polar. Try to replace these with film caps if you can. In fact, any cap under 10 uf, you can probably find a film or ceramic (not COg) cap to fit.
    Oh, there has been a nomenclature change. Caps marked xx MF in 1970, are sold as xx uf, now. Illiterate sales people think u is the same as a greek micro character with the leading tail.
    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.

  8. #8
    Senior Member paulj0557's Avatar
    Join Date
    Oct 2010
    Posts
    1,502


    Grew up with a dad who was an engineer and I pretty much lived at the shop sometimes. Know uf far more than mf. Saw the uf on pretty much everything.
    My intentions are to change out the power supply electrolytic's for now. The organ sounds good, just the fuse thing for now. The Cap' cans are outrageous! The idea of cheating and installing a few radials inside the gutted can is what I will live with for now. Learned my lesson about changing out everything at once though. I have a Thomas Palace that keeps blowing fuses because I changed every cap at once in the entire pedal/amp assembly ( Thomas puts entire organ's power supply and amp system). It's not that I can't fix it, but I kick myself because I did it this way. I recommend changing out caps one at a time. My Thomas was working, but had a hum. At any rate, it seems to be across the board with the old organs that the power supply caps will need changing. At least i have a schematic for the thomas. The Wurlitzer I don't, however Wurlitzer's are A1 professional modular chassis that are laid out very open and are logically constructed, like Hammond. If Wurlitzer has a parts layout in their service manuals it wouldn't surprise me. Isn't it ironic that the companies who have the best layouts also include these drawings, but the ones who cram everything in don't have a parts layout in their service documentation?

    Still hoping someone will upload a 4500 power supply schematic especially.
    BIG SCORE 5/9/14! FOUND $80 WURLITZER BRASS HORN IN CASE WITH STAND,LONG & SHORT BELL
    Wurlitzer '46' Model 31 Orgatron & 310 rotary cab, 56' 4410 , 65' 4300
    Hammond '55' S6 Chord Organ,HR-40,ER-20, Altec A-7(SOLD but missed). '6?-7?' X66 & 12-77 tone cabinet & L112 spinet [latest addition to my collection]...my RT2,Elegante,Leslie 31H sold
    Gulbransen 61' 1132 '76' Rialto II & Leslie 705 + two 540
    Conn'68' 543 Minuet '57' 406 Caprice '59' 815 Classic (the 29th 815)

  9. #9
    Senior Member OrgansR4Me's Avatar
    Join Date
    May 2008
    Posts
    1,702


    Try to get a fuse labeled slow blow. I was having a similar situation when my Conn 720 Artist was getting older and couldn't get it restarted with a regular fuse. Then I notice the one that quit was labeled slow blow. Purchased a few and the organ played on until I gave it away. Decided I wasn't ready to redo the power supply, which sometimes I regret. It was pleasing to my ears. The recipient found a way to disconnect the diapason circuit to kill a mild cipher and last I spoke with him continues to play it using just the flutes. He preferred the Hammond Sound but of course he couldn't get the full effect with the Conn not having the ability of the Hammond drawbars to "mix" the sound levels of the various footages.

  10. #10
    Senior Member paulj0557's Avatar
    Join Date
    Oct 2010
    Posts
    1,502


    Usually those ciphers are just key contacts not releasing from the contact bus, bend them away a little or readjust with set screw. Don't ever be afraid to explore the organ and figure some things out. In the end you can save a ton of money, time, and with tech skills comes more confidence in playing, I think.

    I've turned my attention to my Thomas Palace III temporarily, but I'll get back into the Wurlitzer soon. Appreciate all of the advice.
    BIG SCORE 5/9/14! FOUND $80 WURLITZER BRASS HORN IN CASE WITH STAND,LONG & SHORT BELL
    Wurlitzer '46' Model 31 Orgatron & 310 rotary cab, 56' 4410 , 65' 4300
    Hammond '55' S6 Chord Organ,HR-40,ER-20, Altec A-7(SOLD but missed). '6?-7?' X66 & 12-77 tone cabinet & L112 spinet [latest addition to my collection]...my RT2,Elegante,Leslie 31H sold
    Gulbransen 61' 1132 '76' Rialto II & Leslie 705 + two 540
    Conn'68' 543 Minuet '57' 406 Caprice '59' 815 Classic (the 29th 815)

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •