Messages

Those pics show up great!
I don't see anything different between the two visually except for the different types of capacitors used in each circuit (ex. C2 C19 C7 etc.).
It may be that the older capacitor types they used on the MK I  gave more desirable results for frequency response? They are definitely marked as different revisions on the circuit board, but I can only find one version of the schematic for this pre-amp?
Hopefully someone else can chime in and enlighten us more on the differences.

Your picture link says no access granted when I click it. Without seeing them it's hard to say.
It's a very interesting point you brought up though. I never thought of comparing the two preamps because I assumed they were internally identical.
I would suspect that the op-amps may possibly be different chips or the caps in the audio path may need to be reviewed on the weaker unit.
I don't have the two varieties at this moment or I would try the same comparison. I only have a 1980 MKII preamp to look at right now. I have changed the op-amps on it though.
I am going to look back at my pics of MK I units I worked on in the past to see if anything stands out.

Well, without having it in front of me, it's  hard to guess the issue. The other problem we have here is that I probably know just enough to get you into trouble. I am a hobbiest and am not working on these daily.
That being said, it seems like the obvious is that the ampflication is not happening effectively. I would consider any transistor stage where gain is expected,and, it may also be that the voltage at the pickups is not high enough to effectively pick up the vibrration of the reeds (voltage multiplier stage I fixed on mine) and feed the amplification stage.
The schematic is usually posted inside the unit wich makes it much easier for a tech to look at and figure out.
Hope this helps you some.
I would like to hear what the fix ends up being.
Best of luck, and If I can help further, please let me know.
Vance

I agree. I think it's possibly an omni 3500. Basically a combo organ

Andrew,
if you are not sure, it is probably best to have a tech look at it. Capacitors can and do keep a charge when a unit is unplugged and can zap you 8f you are not careful. This circuit doesn't have very large filter capacitors ,so it is not as likely to hurt someone, but you should treat it as if the risk is always there.
You might try blowing off the board "unplugged" with an air compressor to clear up the stuff that settled on the circuit. Let it sit for awhile after blowing it off to let any moisture dry before plugging it back in.
Maybe you can find a local tech that might be willing to help you look at the circuit if the previous steps don't work out.

These are some pics of the headphone jack contacts and the high voltage section I ended up rebuilding. Solder job is not as clean as the factory, but she sounds nice now.
If you end up working on the amp, the electrolytic caps would be a good thing to replace while your in there. The amp itself most likely needs a good general cleaning off. The amp is placed exactly where all dust and debris come to a rest. Actually, might not be a bad place to start as a cat hair or something could get in there and have shorted something out. Don't forget to disconnect the power if you are in there!

Thos is a pic of my 612p Steveo. It's electronics are like a wurlitzer with reeds and electrostatic pickup. It is IMO, much less expressive, but unique in its own way.

You might start with the headphone jack plugs. Clean the switch contacts with something like deox. If that dosen't do the trick it may be more complicated. I had to rebuild the high voltage portion of my unit to get it playing again.
Be careful as there is a possible shock hazard and it could be hazardous or leathal if you are not comfortable with electronics.
That being said, i will look for my pics and post them if it helps.
Congrats on your find!

Great info! Thanks!

I would definitely take a careful look at that amp. It appears to still have the original "death cap" hooked up. A grounded ac socket has been added so it  is probably only going to trip a breaker if it shorts, but,  im not sure it should still be there?

I had seen that listing and was wondering about that piano myself. From the pictires you provided, it does look to me like a 120. The amp looks pretty much identical to my 700 wich is a consol version of the 120. The inner workings of the piano look alike as well.
These have their own character and I would not say it sounds or plays like the later 200 series pianos. I was going to mess around with mine and sell it, but the selling part never happened.
Something fun about these I can't put into words.
Congrats on your find!

Very nice work there! I actually didn't know any of the suitcase pianos had the single harp support. I have only seen this on the KBS student pianos. That will be quite a gem when you have everything sorted out.
I think more and more people are using these pianos for personal use at their homes/studios than in the past. If it were not to be moved that often, and the sound is amazing, the weight shouldn't be much of an issue for this type of user. The possible heat issue does scare me a bit though. I'm sure you'll work it out.
Thanks for sharing this build. I can't wait to see, and wish I could hear the finished product!

If that black transformer in your picture is going to the preamp, I would say the mod is for that to power it and the two plugs added to the preamp are possibly right and left outs?  I don't see where the rca for the harp is connected. Looks like a couple of power resistors  and the orange capacitor were added for the added power supply. Not sure if that's a voltage regulator I see with them there as well.
Just guessing though. I would definitely have a tech look closely at it.

Cool! Glad that was all it was. Never hurts to check out the simple stuff first before dishing out the big bucks.

Sometimes the effect send receive plugs corrode and can cause signal loss. You might try plugging a 1/4 audio cable into the send and directly back into the receive ports on the pre amp and see if the audio changes. If it does not change, then I would suspect possible bad solder joints in the amp boards or an issue with the din plug.
You might also try removing and pluging back in the RCA cable where it attaches to the harp.
Many things can cause an issue like this, but these are simple things you can try.

I have seen a few items like this pop up as well. I have to admit they do get my curiosity  going. Custom can be a very cool one of a kind thing, but it can also burn your house down or fry your rocky mountain oysters  if it wasn't  done right. I am a tinkerer at heart so I would also be glued to a show like you mentioned.  Fails would add to the excitement for sure...
I am suprized nobody has stuffed a Rhodes into the trunk of a 59 caddie or other late 50's super finn car trunk.

The later run of markII pianos were designed like this. I have never played one to compare how they work to the older piano design, but looks kind of neat.

It looks like escapement is pretty much defined by the block they rest on.  Seems like you would loose some adjustment options here?

Glad you found it useful. I was really shocked that the original owner had kept the manual with the piano. It is really short and simple, but it is the most info I have ever found on this piano.

Amazing collection of instruments you have there!
It is very entertaining just to browse through your site. Your customers are/will be very lucky to have access to the variety and quality of instruments you have available.
Best wishes on your new business venture!

If this is only running 10w, a 2 amp transformer might be a bit over kill. I think you can find a 1.x amp transformer that should do the job. It should be around 3"x3" physically. I would try putting "40VCT" or "40 volt center tapped transformer" in the search engine and see what comes up.

Maybe this one?
http://www.alltronics.com/cgi-bin/item/97E024/E/40VCT%2C%2D1%2E2A%2DTransformer

I agree with OZDOC. 20v on each side with center tap. Also make sure it is rated to handle enough power for the piano. Looks like around 2amps should work well if the size will permit you to fit it.

Are the vents you see on the top panel or the back panel? I was referring to the top panel when I brought up the vent slots. They may be there, but my old eyes aren't picking them out for me. Regardless, it does seem the action is very close to the back of the piano.
I searched some pics posted on the net last night of 120's and it appears (visually again with aged eyes) there should be at least 3 to 5" depth between the back of the action and the back panel.

I can't see how they would save much weight from the chop. Too bad they didn't just remove the amp and carry it separate. 
 

Thanks for the advise Steveo. I did place keys as I worked on the rail. Some pins were turned and needed to be aligned as you mentioned. I clamped from front to back and top to bottom as I worked my way down the rail. A lot of clamping, but it appears to be working.  I'll know for sure when everything is dry.

Maybe I'm wrong,  but it appears that there are no vent holes on the top towards the back as I have seen on other examples shown on the Internet.  It is hard to tell from the pictures,  but wouldn't there be more space from where the action is and the back of the piano? I have never had or seen a 120 in person so I am just going off images on the Internet.
I am curious if it has or has not been modified. 

I was not able to find anything here so I'll throw out the question. I have a new project piano that the front rail has somehow split all the way across the rail.  I am going to attempt to clamp glue and screw the rail back together. So far the fix appears to have worked.
I am not sure how this damage may have happened, but there appears to be liquid damage to the front left of the piano. I don't see any obvious trauma to the front of the piano. I am thinking maybe the liquid caused the rail to split and it followed the grain of the wood all the way to the other side?
Anyway, we'll see how this ends up. I was just curious if anyone else has dealt with something like this and if there is a better approach. I should have probably asked before I started on this,  but the thought only crossed my mind after I was well involved in the repair process.

That's what was different! I had seen that ad but couldn't figure why it came with the older amp separate.  Might be fun project for someone. Although, probably a major over investment, It would be interesting to see if you could stuff a Warneck amp in it.

Nice! Glad to hear that was the only issue.

It may not be the proper way, but this is how I do it.
You should be able to pinch/compress the plastic tab on the plastic clips with a pair of needle nose pliers close to the board so that they can clear the holes in the board. Just apply gentle but constant pressure to the board as you go around to each of the clips and it should work off.

Yes, i do believe the molex connector bases are entirely held by solder. I am sure that is why so many people have seen issues here.
Adding the hot glue to the bases is a very good point to bring up. It would be an easy and effective upgrade that could possibly prevent future issues. I started adding the glue myself to these connectors after reading about someone else ( I think it was voltergeist?) mentioning it.

Not necessarily. I have run into similar problems with this amp and cold solder joints on the amp boards where the wires were soldered in are usually the problem. The contacts for the headphone jack switch are also worth cleaning while you are in there. This may not be your issue, but it is the easiest to look at before replacing components. Best of luck,
Vance

I was watching that one shhhhh!

It is most likely a 72 as stated in the ad. Mine is from the same vintage with the same badge on the rail. The emblem is actually different from any other model I have run across.  If you pick it up and want to put new hammer tips on it, you will probably have to remove a little wooden notch on the hammer of each key to fit them. I have not replaced the felt tips on my hammers yet, but they need to be replaced. I cant bring myself to modify the hammers. Nice piano, but heavy and awkward to move. A modified Voltergeist version would definitely be nice to have around though!

I agree, the technology of the reeds is very similar, but the sound is definitely different. I think the action of the keys may have something to do with that. I don't feel that it is as expressive as a Wurly. It has it's own character/flavor and thats why i appreciate the instrument. I would not encourage those looking for a Wurly to seek out one of these.

I was afraid someone might bring one of those posts up.
I never said i could play, but that never stopped me haha!

It uses reeds much like a Wurlitzer. The 612p has a reed bar and uses high voltage just like a Wurlitzer. There is a Elepian branded version that uses individual pickups,like a Rhodes, it is amplifying metal reeds instead of tines.

The one i ran across was purchased by its owner from a sale at a SF college. I do believe many of these were sold to schools.

Congrats on your find Quincy! I can't help but like the Maestro!  They are no Rhodes or Wurli, but they do have their.own unique flavor. 
Ill see if I can post some of my pics of mine from my phone. I have a pic  of the schematic but I don't know if it will show well here. There is  a small  manual with minimal info. I posted the manual here a. little while back. I'll see if I can post a link to it.

http://ep-forum.com/smf/index.php?topic=8272.msg43754#msg43754

I have yet to find any hard info linking this piano to Gibson or to the manufacturers of the similar Elepian model mfg. in Japan. Hopefully something will surface to bring some more clarity to this piano's history. 

Unless this strikes a specific chord with someone here, I don't think there is an easy answer to your question. There can be a number of things that can cause something like you described. I usually look for easier to solve issues like cold solder joints, connections with corrosion, like you mentioned. My next step is to look at hardware that has not yet been addressed, maybe the zener diode etc...
Cell phones, fluorescent lights,  items on the same power strip or circuit can also introduce something like you described.  In short I guess i would recommend taking a second look at everything closely. I have overlooked things many times before and only isolated the issues after stepping away and coming back to take a fresh look.
Best of luck with your project.
Vance

I would avoid the power washer. I found some really good advise here;
http://ep-forum.com/smf/index.php?topic=3896.msg17587#msg17587
I used this method using a soft bristle brush, windex and a clean towel for wiping with pretty nice results. You don't want the wood frame to get too wet or it might warp on you.
You can pretty much do the same thing with cleaning the tolex. 
I personally prefer original hardware and tolex if it is not in really bad shape. Im my opinion, It lets the piano tell some of its story.
Replacing tolex and hardware is a pretty involved job and may compromise the piano's value if it is not done properly. When done properly, I have seen some piano's fetch higher prices. But, if you change from factory colors you may limit the buying audience.
I personally would be much more careful when buying a re-tolexed piano by someone who has done this for the first time.  The action and hardware have been removed and replaced which may leave plenty of room for mistakes.
This site has plenty of great information and users with amazing knowledge on these pianos, which ever choice you decide to do. I am still very much a beginner, so, I would hunt around with searches on this site first and maybe wait for a few others to chime in before committing to your decision. Best of luck with your project! 

The FET mode noise you are describing reminds me of cell phone or wifi interference. I have set my cell phone on top of the piano and went hunting for the crazy sounds, not even thinking about the phone reacting with the harp. Is there a way you could use a foil or other metal shield around the unit to try and eliminate the interference issue?

Congrats on your new piano, it looks to be in really nice condition! Those don't show up every day. It's good to hear others are crazy enough to drive long distances for these treasures!

Voltergeist,
Your first response was something I was envisioning doing for a similar piano I am sitting on, then I read your second response and was shocked. I was not aware VV was producing new power amp blocks. I went to their site to look, but could not find them. Are they not listed yet?
Great advise either way, but in my case, I would prefer the new power amp modules. If they are reasonable enough, it would be simple, clean and less confusion for the next tech that might have to look at it.

Greetings,

There seems to be so little information about these out there and I ran across this with my recent 612P. Maybe it can help someone with the AUX PU1 and PU2 outputs. It is also kind of fun to read.

That is a really neat idea! I remember reading an article on the internet where they were introducing resonant frequencies to the tine/tone bar assembly by attaching a piezo electric element and creating a never ending sustain for the notes. It will be interesting to see your results for tone bar tuning.

If you don't have much experience in electronics and pc board repair, you might want to take this issue to a tech. A wrong move can cause much worse damage to your keyboard then it already has or even cause fire, a shock hazard or death!

This may or may not solve your issue, but is easy enough to try.
Always test with the power cord unplugged! You can use an ohm meter set for continuity. Start from the contacts from where the key contact depresses and follow the very thin wire trace on the pc board that leads away from that point until you see it's next solder joint. If your continuity tester shows no resistance or closed, then it is ok. If it doesn't, or shows open,then you might have a corroded or broken trace. There is possibly one or two traces on the keyboard that have  either corroded or broken and can cause a number of keys to not respond. If you find a broken trace, you can take a small insulated solid core wire and tie the two solder joints together to make the circuit connect again. Pre tin the ends of the wire so you don't end up putting too much heat on the pc board. Attach one end to the solder joint closest to the key contact and the other at the end where you found an open circuit.
Double check with a magnifying glass that you have followed the right trace before attempting to fix this. It is very easy to get traces confused as small and close together as they are.

I was working on sorting out some DMP rail goodies for a stage 73 and started looking into the DMP history and products. From Chuck Monte's site, I ran across this link to Masaki Mitsuhisa's site.
http://ww3.sunnyday.jp/dmp/index.html
I noticed a small grainy out of focus picture of an old Wurlitzer with a bunch of electronics stuffed into its lid.
A title to the left refers to it as a (Wurlitzer Super "B"). I can find no more information on this piano. I assume it was something that was never released. Does anyone know what was modified on this piano or if it was ever released? Were there any other Wurlitzer EP products by DMP?
Just thought I would throw it out there...

That's what I did.

Found an old pic. I used solid clear coated magnetic wire that I had handy at the time, but I don't suggest using it. It doesn't let you manipulate it easily.

I did it with mine. The wire on mine was in pretty bad shape with lots of corrosion. If it was not so corroded, i probably would have passed. I don't like messing with soldering the delicate pickups if I don't have to. It went well though. It did seem to have a bit more output, but that could have also been due to the old wire. The process took a bit of time to accomplish.

Sounds great and the legs present very nice on stage. My neck may need some work after the video though.....

That is interesting about the listing of the 210 you shared has 214 written on its power rail. The 210 I had was also marked 214 on its rail in the same area. I can look for a pic if you need it. They probably shared amps as they are running the same speaker configuration. I still have my 214 classroom piano and one other thing I remember being different is that the 210 had no student shelf that pulled out. The 214 has the shelf and all of its metal hardware ( name rail, music stand, knobs, legs) is gold instead of the more common silver.

Nice list! It's great to see this information combined into one reference location. It seems I am always looking up models I had previously looked up before because I keep forgetting which model had what feature. 
I noticed your list had a question about the 210's speaker configuration. I had a 210 and it was equipped with 4x 8" speakers in the lower cabinet and none in the upper case. Two were attached facing the audience side and two facing the players side. 
Thanks for sharing your research into these models!

Just curious. Do you have the same problem if you listen to the piano with headphones plugged into the headphone jack? It is located on the main amp. Sometimes the jack gets corrosion and can block the audio signal from the preamp to the main amp. This is a long shot, but easy enough to try.