Yamaha Electone FS30 Problems

[skippy]

Hi Folks,</P>


I justa<SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-AU; mso-fareast-language: EN-AU; mso-bidi-language: AR-SA">cquired </SPAN>a Yamaha Electone FS30 with a problem. The organ appears to function correctly butproduces a low volume distorted sound only. When I opened the back I found a blown capacitor mounted on asmall vertical board in the very left bottom corner of the organ in front of a transformer. I replaced all 3 capacitors on this board but the problem remains.The same distorted sound comes through headphones as well. If I connect my Leslie 705, the rotor speed control functions but no sound is coming through the Leslie. It appears to me that this may be a pre-amp or expression pedal board problem. Any ideas? Also, where can I get a reasonably priced Service Manual? Your help is greatly appreciated.</P>


Cheers</P>


Skippy</P>

[fredy2]

Re: Yamaha Electone FS30 Problems

First thing is to check the power supply voltages, especially the plus and minus used by analog sections. You will probably find a +/- 12 volt and/or +/- 15 volt supplies. These power the analog sections and if one is missing, the symptoms would be as described.

[skippy]

Re: Yamaha Electone FS30 Problems



Thanks Fred,</P>


I am getting a service manual in a few days on a one month hire for AU$11. This is a pretty good deal, considering that one has to fork out between AU$80-90 to purchase it. Here is a link http://www.hcsd.com.au/or phone 03-57711277. Stephen runs the show. A very helpful chap. He has a 300K manual archive.</P>


Here is what I have done so far. Replacing the cap made no difference. It looks to me this cap may just be there to reduce the popping noices of the on/off switch -just a guess. I connected a CD-player to the AUX in terminals and all 3 amps are sounding great. I had a look at the small circuit board mounted on the rear of the expression pedal. It has one 4558 and one 1458 general purpose dual amp chip on it. Also a voltage regulator 7815. Judging by the messy soldering, the two chips had been replaced previously. I took a punt and replaced the two chips and the voltage regulator. Still the same. I disconnected the 7 pin plug from the expression pedal circuit board. I still got he same low volume distorted sound but with a bit of hiss in it.And of course there is novolume change by operating the expression pedal.</P>


Perhaps the previously replaced chips are the wrong ones. The service manual will tell. What do you make of this??I really appreciate your input.</P>


Cheers,</P>


Skippy</P>
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[fredy2]

Re: Yamaha Electone FS30 Problems



I am working from an FX20 schematic which has a lot of commonality with the whole FX and FS line.</P>


The expression pedal uses a lamp (first thing to check) and an LDR (light dependent resistor) as the variable element... this is just a start...</P>


The LDR in conjunction with those op amps sends a signal to the EAP board. There, it is processed analog wise by a lin to log current convertor.</P>


The output of this goes to a pair of series LED's that shine on more LDR's for the various audio channels of the organ.</P>


First thing, make sure that lamp in the expression pedal is lit.</P>


Next, does the master volume control have ANY effect at all? The master volume is AFTER the actual LDR's that are driven by the lin-log convertor which was driven by the expression pedal.</P>


I will be gone part of the day. You can also direct email at [email protected], although it is good to keep replies visible to others who may learn from the forum.</P>

[skippy]

Re: Yamaha Electone FS30 Problems



G'dayFred,</P>


Yes, the lamp in the expression pedal is lit and the expression pedal increases and decreases whatever little volume there is. But it does not appear to change the volume of the bass and the rhythm.The master volume control works on all sections of the organ. I have to turn it all the way up to get the weakvolume.Distortion is most prominent on string, cosmic and vocal voices - increasing when theexpression pedal is pushed down.</P>


Cheers,</P>


Skippy</P>

[fredy2]

Re: Yamaha Electone FS30 Problems



With th master all the way up I would expect distortion...</P>


Do you have access to an osciloscope?</P>


It sounds like there may be a problem farther back... I worry that it might be in the D-A convertors... I will have to plan next troubleshooting thing... in the meantime let me know if you have a scope available.</P>

[skippy]

Re: Yamaha Electone FS30 Problems

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thanks Fred,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Yes, I have just a cheap Dick Smith 10MHz single channel job. Never had to use it. Always got away with the multi meter and guess work fixing the old analog beasts.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Cheers,<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Skippy </SPAN></P>

[fredy2]

Re: Yamaha Electone FS30 Problems



That should work for us.</P>


Can you find the MEP board?</P>


On the MEP board are the LDR's which control the volume. There are a bunch of 8 lead OP amps. CAREFULLY verify that at least one of these has +15 on pin 8 and -15 on pin 4... be VERY careful to not short anything.</P>


IC1 through 4 have audio on pins 1 and 7. IC 5 has it on pin 1 only. These are the audio drives to the 9 LDR's that go to the audio buffers.</P>


See if there is a reasonable level of audio say on IC2, pin 1. This is the right channel mixing...</P>


IF you have a few volts audio there then we move downstream... ALL of those op amp pins I mentioned should have zero volts DC bias... If you find one that doesn''t, then we are on the trail of a failed coupling cap...</P>


The outs of the LDR's on this board go to buffer op amps in IC6,7 and half of 8. These drive FET gates that kill the audio while resetting.</P>


Going back the other way heads toward the dreaded DAC convertors.</P>


Instead of holding a key down to generate audio, IF the rhythm seems to be working, run it at full level and check the audio at IC3 pin 1. This is ryhthm left channel.</P>
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[skippy]

Re: Yamaha Electone FS30 Problems



Hi Fred,</P>


I expect to get the service manual today or early next week. I will wait until then. No urgency to fix it. I picked up a cheap Elka EP12 that is working perfectly. It is almost a carbon copy of the Yammy FS30. That will keep me amused until the $50 Yammy is fixed.</P>


Thanks again and have a good weekend. I will keep you in the loop.</P>


Skippy</P>

[skippy]

Re: Yamaha Electone FS30 Problems



G'day Fred,</P>


I have measured IC's 1 to 5 on the MA Board with the Rhythm going and a few notes on the upper Keyboard playing at full level. Here is what I got:</P>


IC1: Pin1= +0.1V, Pin7= +1V (Both just flat voltage - no audio ripple)</P>


IC2: Pin1= +13V flat voltage, Pin7= audio ripple spanning over appr. 6V</P>


IC3: Pin1= -0.4V, Pin7= +5V (Both just flat voltage - no audio ripple)</P>


IC4: Pin1= -13V, Pin7= +0.1V (Both just flat voltage - no audio ripple)</P>


IC5: Pin1= 0V, Pin7= 0V</P>


All IC's show +15V on Pin8 and -15V on Pin4</P>


What do you make of this??</P>


Cheers</P>


Skippy</P>
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[fredy2]

Re: Yamaha Electone FS30 Problems



IC3 pin 7 at +5 volts cuts off the audio, The current through TR1 will be zero as well as PC1 and PC2. You will get no audio volume. D23 and the other diode and the associated resistors generate a non-linear curve of voltage for the xpression control. You should see this voltage on pin 7 go negative when you move the expression pedal up. The collector of TR1 should move to less negative as current flows through PC1 and PC2 to illuminate the LDR's that pass the audio.</P>


I will leave it to you to find if this happens... if not trace back toward the expression pedal.</P>


IC1 pins 1 and 7 are REASONABLE</P>


IC2 pin 1 is UNREASONABLE</P>


IC2 pin 7 is REASONABLE</P>


IC3 pin1 REASONABLE</P>


IC3 pin 7 UNREASONABLE</P>


IC4 pin 1 UNREASONABLE check input cap or the IC itself.</P>


IC4pin 7 REASONABLE</P>


IC5 BOTH REASONABLE</P>


First run down why IC3 is + instead of negative.</P>


Fred</P>
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[skippy]

Re: Yamaha Electone FS30 Problems



G'day Fred,</P>


Here is an update on the FS30 progress. I checked the voltage on the expression pedal. It supplies 4 volts on low and 12.5 volts on full. This appeared to be reasonable so I concentrated on the MA board. I replaced IC's 2,3 &amp; 4 and all associated 10 &amp; 22 pF caps and TR1. This brought back the volume with IC3, pin 7 reading -4.2V. Also the collector of TR1 is reading a negative voltage. </P>


However, only the centre channel appears to work correctly. The right and left channels appear to process symphonic, tremolo, reverb and some rhythm signals. While the left channel is totally dead, the right channelsounds terribly distorted. The distortion will cut out at very low volume. I get the same results using head phones or the external Leslie 705.</P>


Here are the results of the IC pin voltages now@ half master and pedal volume</P>


IC1, Pin 1= 0VPin 7 (left Channel)= +1V</P>


IC2, Pin 1(centre channel)= +11.5V Pin 7(right channel)= audio ripple over 3V</P>


IC3, Pin 1(main mix going to ext.speaker outs &amp; head phones)= +7.5V Pin 7(Expression Control)= -4.2V</P>


IC4, Pin 1(External In)= 0V Pin 7= 0V</P>


IC5, Pin 1= 0V IC5, Pin 7= 0V</P>


The right channel appears to have the audio coming through but it must get somewhere overdriven/distorted on the way to or through the TR board. Tomorrow I will follow its path and compare its signals with the good signals from the centre channel. And I will do the same with the left channel. Am I on the right path??? You have no idea how much help you have been. I would have never gotten this far without your help. THANKS AGAIN.</P>


Cheers,</P>


Skippy</P>
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[skippy]

Re: Yamaha Electone FS30 Problems



G'day again Fred,</P>


On second thought I think I will start looking upstream towards the symphonic, tremolo and reverbsections to find the problems with the left and right channels. I just realized that the symphoniccentre channelsignalssound distortedthrough thecentre channel while all other signals sound clear. This would indicate that all is well downstream, at least for the centre channel. What do you think?</P>


Cheers,</P>


Skippy</P>

[fredy2]

Re: Yamaha Electone FS30 Problems



Great! Our analysis of the expression voltages worked out... Did you RE-check those same voltages?</P>


There are some real insidious faults such as broken traces or dendritee growth.</P>


If all the voltages changed to reasonable values after the chip replacement then working upstream is the way to go...</P>


Your reply said 22 pf... I am sure you meant 22 mfd caps...???</P>


Also these are polarity sensitive of course.</P>


We are working toward the dreaded D-A convertors... those are a bit hard to find replacements...</P>


I would suggesst getting a little battery ISOLATED amplifier to aid in tracing the signals... isolate the input from the test points with a .1 mfd cap.</P>


It is strange that several IC's must have been bad... that is NOT a usual failure...</P>

[swjackson]

Re: Yamaha Electone FS30 Problems

[quote user="fredy2"]

It is strange that several IC's must have been bad... that is NOT a usual failure...</p>

[/quote]</p>

I am also working on an FS-30, and I was finding so many faulty 4558 op-amps, that it was quicker to just replace all of them (and they are only $1 a piece) to be sure. However, rumour has it that this particular Electone was struck by a power surge! It is still without tremolo and symphonic, so if I get stuck, I may start another thread....</p>

One question if I may? I have the service manual, and the circuit has many 'test points' marked TP10 etc. This sounds like a great idea, but I can't find anything that tells what to expect at these test points. Some are obvious, as they are at op-amp outputs or similar, but some are not. Do you know if there is a list of TPs anywhere?
</p>