peterson suitcase troubles!!!

[christopher ross]

Good day fellas!!  This is my first post, yall have helpful thus far. Thankyou.  I recently purchased, a 1974 mk1 88 key.  I had been searching a while and finally got one for the house .  i've loved the rhodes sound since i can remember.  big problem:  I have no sound!, only a deep dark chopped up clangg  on a couple of keys (when i pull vibrato on--no sound at all).  I played piano through my guitar amp and got beautriful sound, though still needs tune/voice.  i plugged my guitar into the suitcase channel 1+2 and got sound from all four speakers with piano unplugged.  i'm not sure what i should explore first, just thought i should throw my feeble findings out there.  

aside of  the said experimenting, i've taken the grills off and visually inspected the inside of the cabinet.  i removed preamp and checked for the two lights which appear to be functioning.  also, i've tested the pickups with a screw driver tip OK, no corrosion, loose grounds/wires.  the four pin cord has good continuity.  i'm timid with any thing further due to lack of direction, if i could just isolate the trouble, my head would spin slower.  any  insight is much appreciated.

thanks guys,

chris

[Rob A]

Sounds like you've isolated it to the preamp, but I want to double check one thing. You said:

i plugged my guitar into the suitcase channel 1+2 and got sound from all four speakers with piano unplugged.

If it's a Peterson, it shouldn't have inputs, just outputs. Does the panel look like this one? http://music.linear1.org/i/pict4933.jpg

[christopher ross]

Thanks for the reply!

That picture is pretty close to what i have,  except mine says Fender Rhodes, and there is no reset button, only a (SLO-BLO 2 amp fuse), also, by the power connection it says 117 volts, 60 cycles, 2 amps.

I plugged my guitar into the external amplifier 1 and 2, again, just to make sure i heard sound on all four speakers.  I can play through it but the volume is determined by the dial on my guitar,  it is not very very loud (so as to wake the neighbors) but it is as loud as my  mesa boogie, maybe,a quarter of the way turned up.

I dont know what to make of it all, i'm having trouble tuning the highest and lowest notes, when the piano is plugged into the guitar amp, how do I know if I have a bad tines?

Thanks man ,iwant to play like gwiz

chris

[Rob A]

Those are outputs for driving external amplifiers--I'm not too sure what to make of you getting sound when you plug in to those. I use those outputs to record mine. I guess now that I think about it, it's probably an input too. Let's proceed with the following test, which treats it as an output:

Take your guitar amp and connect the number 1 output into your amp input, and see if you get sound that way. You should get a steady tone with the tremolo off, and a mono tremolo tone with the tremolo engaged (since you're missing half of it). Repeat for channel 2. If you get good signals, then your problem is in the suitcase bottom amp modules, because these outputs are "downstream" from the preamp. You should be able to affect the tone with the tone knob and the volume pot as well when connected like this.

If you don't get what I describe on that test, then you probably have some work to do in the preamp.

Give that procedure a spin and get back to us.

[Fred]

Sounds like a pre-amp problem if you're getting sound from the cab. Have you checked the connections between the pre and power amp? Even if the cable is fine, those connections (especially the one on the amplifier) are notorious for getting loose and dirty. Try cleaning those connections and move the cable connectors around a bit to see if continuity is intermittent. Do the lights on the preamp blink according to vibrato speed? While you're in there, check for any cold solder joints on the preamp board...

[christopher ross]

HI guys, much thanks for weighing in on this.  Rob, I tried each channel plugged to the input of my guitar amp and got the same result as before, i'm assuming that i need to have the suitcase plugged in to power as well.

Fred, good to meet you!  this is such a cool place!  What fun,  i dont see any change in the light when the speed is altered, in fact when i pul it on, the two square shaped lights on the under side of the board go out. i'm not sure what to expect.

got to run (my lunch hour is over)  thnaks again
chris

[Fred]

This could be a source of your troubles. The Peterson pre amp uses photo sensors to detect light from the bulbs, and complete the curcuit to direct the signal to the power amps. In other words, no light, no signal. Both lights should be on constantly with vibrato off, and blinking alternately and at a variable speed to interupt the signal creating the stereo vibrato effect...

[christopher ross]

hey there Fred, i'm guessing that cold solder joints are bad connections??  anyhow, i've got every thing apart now, and i'm wondering where the LEATHAL voltages are located,  you know, so i don't stumble upon them inadvertently.  I have an analog meter to test for shorts/opens and a multi meter of which i am not so familiar with (i wouldn't know what  setting to put it on, or what type of signature to look for).  while testing with the analog meter i have noted that pins 1 and 4 seem to be shorted out while nothing is connected. one of the prong teeth on the input plug has broken off, but there is still contact being made.  i went through the pre amp circuits and tried to see if there were any loose resistors (every thing seemed fine).  there was what looked like one sloppy joint that might have been arc-ing between two conducters tied into the outside light module.  maybe this could clear things up, who knows just yet?  while the cab is empty i'll give every thing a good cleaning, and put an order in for a new input.  any other advice  while everything is open?

thank you-----chris

[Rob A]

No lethal voltage in the preamp,it gets 25VDC input from the suitcase bottom.

http://www.fenderrhodes.org/ch11/fig11-8.jpg

[Ben Bove]

As long as it's open you may want to contact clean your pots if they're scratchy when raising volume etc

[Fred]

A reading across pins 1 and 4 is normal, not necessarily a short. Have you confirmed proper bulb function? You may also want to flow the board, too... Apply flux to all solder joints and heat with a solder iron. Move quickly...Make sure the joints have flowed, but don't cook anything! Try to rule out the obvious causes like loose connections or burned out bulbs first... If you know someone else who has a 4pin suitcase, you could always hook up your preamp just to be sure the problem is in the pre in the 1st place, though if you got the guitar playing through the cab...seems the power section is working...

[christopher ross]

Gentlemen, there is good sound comming out of my rhodes!  but i can't say that i know exactly what it was that did it.  While i was building up the courage to "flow" the pre amp board, i took everything out of the cabinet, and looked the power supply and module connections over for looseness/dirtyness.  I hit all of it with compressed air because there was quite a bit of dust inside there.  Then I  went ahead and flowed the pre amp board.  I also took all of the keys out and vacuumed the inside of the piano, for that was just as dirty.  When i reassembled the top and bottom,  i had sound from two of the speakers, the volume was at 10 and there was clear sound.   I dont have proper light function yet, and when the vibrato is pulled out to "on" position there is no sound at all, the lights just go out (same as before).
So, I don't know what made the dark clanging crakles go away but i'll take it!
I'm kicking myself for not taking more of a systematic approach. :x  Next, I reversed the mod connections and it appears that the mod nearest the power supply is not working, could this be the reason for the lights not blinking???  should i take it out and flow that as well??

Thank you all for the input

chris

[Fred]

Mod connections? Not following you there...Does your suitcase have two outputs/inputs? If it does, do you get sound out of both when you plug in your guitar? If so, the problem is probably in the preamp.  Are both lights on when vibrato is off? Also, if they are not blinking properly, it could have something to do with the caps in that circuit. They're either 8 or 4.7 uf (x2) and if those or the adjacent resistors are faulty (caps are located to the right of the bulbs, side by side, about  1/2" apart, with said resistors mounted between the caps) you will not have proper blinking or vibrato.

[christopher ross]

I thought that i heard someone call the small black, finned,  square shaped things mounted to the bottom, inside of the suitcase an "amp module" or "mod".  apparently i'm confused as to the name of this piece of electronic circuitry.  Are each of these the same?  they sure look the same.  By connections, I meant the connections at the back of the power supply which connect to the black finned things.  I can plug one of the black finned things into either power source (socket  that power comes from in the back of the power supply) and get sound in each respective pair of speakers.  If  I do this with the suspected BAD square black finned thing, I will not get sound from either of the two pair of speakers.

Yes the two lights are "on" when the vibrato is off,  This is the only time sound comes out, and it is only out of two speakers.
I think i'll look in the manual now and get tha actual name of the square black finned things now.

thanks chris

[Ben Bove]

Oh, you are correct they're referred to as modules.  Just the term "mod" is throw around loosely here as an alteration that wasn't factory - modification.  "key pedestal mod" "preamp mod"  etc.

You do have one bad amp module which is very common.  They're always blowing out for me.  This however would have no effect on the functionality of the vibrato.  You should be able to have working vibrato with one-channel output.  It'll sound like mono wurly vibrato opposed to ping-pong stereo.

So there is some preamp issue going on beyond the bad amp module.

[christopher ross]

lucky me!  good thing i have yall.   are the caps and resistors that fred was talking about something that i need to get from somewhere specific?  because i surely do not have any blinking going on when vibrato is pulled "on".

I'm pretty sure that i do get sound from both sets of speakers when my guitar is plugged into either of the two input/output jacks but i will have to check again to be sure.

thanks chris
[/quote]

[Mark II]

Vintage Vibes offers a 4pin preamp overhaul kit which "only" requires decent "finding parts on the PCB" and "solder" skills. That might suit your abilities, otherwise you wouldnt have asked but took the schematic, found all the important parts and went off to your favorite electronic parts supplier and got the things you need.
:? I hope this doesnt sound to harsh.

kind regards

Mark II

[christopher ross]

thanks Mark  II i thank you for the reply.  the schematic seems i bit more than i can handle at this time, perhaps the kit will tell me where to locate the caps and resistors.  

I think i'll try to repair the amp first, seeing that i've never played  piano.  I don't know what to expect from the feature.  Maybe vintage vibe has a module repair kit too.

thanks chris

[Mark II]

no problem.
the 4pin preamp repair kit from Vintage Vibe has a pic with the main parts delivered where you should easily find the parts to change:

http://www.vintagevibe.com/p-111-rhodes-suitcase-pre-amp-rebuild-kit.aspx

they also offer repair video DVD for the main amp, but I dont think that a newbie ti electronics is able to repair a blown amp on your self only by help of this DVD.

I would bring the main amp to a tech.
the schematic of the amp is on this page aswell, so a skilled tech should know how to get this module working again.

kind regards

Mark II

[christopher ross]

Thanks to everyone, I'll get back and post a picture or two once i get everything back together.  I'm going to try my luck with the two repair kits, it could use some new grill cloth too, for it is a brownish yellow and smells pretty bad.  since Vintage Vibe is where the kits will be ordered from, does anyone know which one of the silvers is the actual replica for my suitcase?

so long, much thanks

chris

[Fred]

Be sure to tell Chris at Vintage that your vibrato is not functioning. If memory serves, when I ordered that kit the vib. caps where not included, but are available. Hmmm....74? Maybe the plain silver cloth? I know the earier suitcases had silver w/ turquoise stripes...Any thoughts bjammerz???

[Ben Bove]

Well I think they both used blue stripes but over the years it fades to a reddish-brownish.  I'll have to check, I have a suitcase from 74 at home and I faintly remember when I removed the kickplate around the pedal, the grill was bright with blue stripes while the normal exposed grill looked brown-threaded from oxidation?

If they're not torn you can probably clean out the yellowed-ness if you don't want to go through the cost and labor to regrille:

http://ep-forum.com/smf/index.php?topic=3896

[Fred]

I have a '75 amp cab that has silver cloth with a gold stripe instead of turquoise. I've encountered a couple of these. Looks original, same smaller pattern than that of the new grill cloth available...

[The Real MC]

The "reddish-brownish" fade is a telltale sign of nicotine.

Remember those "upholstered" Kustom amps?  This store had two heads, one silver and one brownish-yellow.  The latter was originally silver, it had been part of a house system for a bar for over twenty years.  Tobacco smoke had stained the silver to a brownish-yellow, and peeling back the folds revealed the original silver underneath.

Pretty harsh reminder what nicotine does to your system.