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Viewing 1 to (8 Total) EX35 - no volume |
United States
Total Posts: 4
Joined: January 30, 2018
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A customer has an early-90s EX35 that suddenly stopped producing sound. All volume controls are up; neither speakers nor headphones produce sound. All connections appear to be tight, and I did not note any physical symptoms of age or damage. All the fuses are good. The pedal and wiring/connections look good.
BUT... I’m a piano tech and spend much of my time listening very carefully, and I can catch the tiniest bit of sound when I press keys (as though mice were singing in the house next door - extremely faint). I know I’m actually hearing it because the pitch changes as different keys are pressed. I did not hear even those sounds with the headphones, but that might be due to headphone condition.
So, where do I look next? I don’t see a repair manual for that model - is there another that will cover this issue?
And why in the world is there a lightbulb in the pedal? My guess is that it, in combination with the nearby white “board”, is somehow analogous to a mercury switch and senses/sends position information... but how?
Thanks!
Annie
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Posted on January 30, 2018 at 11:28 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: EX35 - no volume
Morning I'll start at the end first! The light bulb is the key to the volume adjustment. The bulb should be on as without it there is no sound or at least very little. The active component is a LDR a light dependent resistor which controls a voltage that works with the rest of the circuitry. There is a shutter attached to the pedal that obscures the light to change the resistance.
Posted on February 7, 2018 at 9:18 AM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: EX35 - no volume
You can hear the sounds of the notes being played as part of the circuitry is a mute to kill off any of what is called beehiving from being there in the background. So we know that the mute lifts when you hit the keys and that the organ is producing the correct notes. My next suggestion would be to plug in an amplifier into the line out sockets on the rear. A jack to phono lead should allow you to plug into these outputs and connect to any stereo system which will then allow you to tell if the organ is actually working properly apart from the amplifier stage.
You can then use the aux in to put any music you like into the organs amplification system. My guess would be this won't work but let me know what happens. Most likely issue is that the headphone socket has failed which has switching in it and it will need changing. If you can hear the notes through the speakers then the other option is a failure of one of the power amp modules. It could also be a failure of one of the 12 volt power rails. I would have to take it to pieces myself to be able to tell you much more im afraid!
Let me know what you find and I'll see if I can come up with anything else!
Regards
Dave Tutt
Posted on February 7, 2018 at 12:16 PM
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United States
Total Posts: 4
Joined: January 30, 2018
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Re: EX35 - no volume
Thanks so much, Dave! I figured that was generally the pedal/lightbulb design but had never seen such a thing before.
Thanks even more for the diagnostic/testing info. I’ll get back there next week with an amp and give it a try. My customer is in his 80s, and he loves that instrument, so he’ll be very pleased just to have me be working toward a solution. And he’d be ok with a work-around, as well. A failed headphone jack makes sense and is a great place to start.
I appreciate this, as will he.
Annie
Posted on February 9, 2018 at 12:54 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: EX35 - no volume
No problem at all Annie
I can't find the manual for that particular model at the moment but I have a feeling the main voice boards are in a card frame at the back in that model. If that is the case then the chances are, with no sound then you may well need to find a power amp module which sits under the keyboards to the right if I remember correctly! Mind you Im getting old and stupid so I may be thinking of an entirely different model! However, those amp modules are known to fail. They are all from the same family usually Sanyo (STK****) and were fitted to all sorts of gear including 1980's hifi amps as well as organs. If it needs one they can be found on ebay at reasonable prices.
Dave
Posted on February 9, 2018 at 2:00 PM
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United States
Total Posts: 4
Joined: January 30, 2018
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Re: EX35 - no volume
Ach, Dave, the website never told me you had replied! Apologies for any apparent rudeness on my part!
I hooked an external amp up to the EX-35 and heard sound, loud and clear. So I take it that points to the headphone jack being at fault. My customer is interested in repairing it himself.
What I don’t know is how the headphone jack functions to cut out the speakers. Does the headphone interrupt or complete a circuit? (And is that even a valid question? My area of expertise is pre-electronic....)
A schematic would help, but so would any advice.
And I will check back to get any replies; I don’t want you feeling ignored!
Thanks,
Annie
Posted on February 15, 2018 at 10:00 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: EX35 - no volume
Hi there
I would love the diagram too! I have a feeling there are 3 different ranges of Technics organs, of which I know a reasonable amount about 2 these being the early ones with the card frame arrangement of some 15 boards mounted behind the keyboards which seem to have had two totally different sets of id numbers depending on where in the world you live and the other which I know as the GA3 FA1 types which along with three other very similar models were all in the same basic design.
I am not sure how the headphone jack on this organ works. If it has a small circuit board with a pair of resistors then the headphones are generally driven from the power amps that normally drive the speakers. The socket is therefore a type that breaks the connection to the speaker when you plug in. The socket will be of the 9 pin type. Easiest way to test this is to do a resistance check at the power amp end and with the speaker plugs disconnected test the leads to see if you get a reading of around 6 ohm with a normal meter. If you do then the chances are the headphone socket is not the fault.
With sound getting out to the external line output sockets it is very likely that the power amp has failed. Be aware it has generally its own fuses, bridge rectifier and smoothing capacitors as well as the amplifier module itself so if its fuses have failed replacement could fix it but it may still need repair work.
From the sx-EX35 picture I found on the web I don't think it is likely to be much like either the E55 or the FA1 series. My guess it is something that is in between these two ranges so I will have to either find one here or have a chat with my contacts to see if anyone has better supplies of info!
Keep in touch. If you get stuck you can always send me some pictures and I can then perhaps be more helpful.
Regards
Dave
Posted on February 16, 2018 at 12:24 AM
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United States
Total Posts: 4
Joined: January 30, 2018
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Re: EX35 - no volume
My customer was apparently an electronics guy in the Navy, so I’m going to forward your comments on to him and let him have at it.
I’m very much a gears’n’levers sort of mechanic; things electrical leave me bamboozled much of the time. But I am glad to know the probable functionality of the headphone jack. That was a fun question to contemplate.
I’ll let you know what happens, if anything. Personally, I think he should buy an amp and get back to playing!
Thanks again,
Annie
Posted on February 18, 2018 at 5:46 AM
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