Definitely a guitar thread not keyboard related

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Re: Definitely a guitar thread not keyboard related

Post by calling card »

I had a Jansen transonic to dial in. I too went changing caps with risk of causing collateral damage and wasting time. I sought help from Mr Crowther as he used to assemble them new. Aside from a broken wire to the keys section all it's issues stemmed from low power supply. I changed out the bridge rectifier and smoothing caps then had to alter a dropping resistor to get voltage to read 15v at source, powered up & loaded.

Not a Korg like yours I know.
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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

Thanks for that. Cool organ! I think there was one recently on TM that needed TLC

So I thinkl the fact that one side is perfectly operational makes power supply less likely, tho caveat to this is a dont know what im talking about.
I think ill work my way back from the output section to the power section. If I can work out how to measure voltage supplied to the op amps prior to the signal split ill do so and see if they are even.
For the $10 spend and half an hour of fiddle (which I acutally dont mind doing with some music in the back ground and a beer this evening) then no biggie
As an aside my most recent interaction with Paul Crowther was him yelling at me some rather hard words when i was wailing thru a hot rod deville during sound check and he was trying to set up drum mics or something. I later attempted to appease him ny pointing out the hot cake on my board but I dont think it helped

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Re: Definitely a guitar thread not keyboard related

Post by calling card »

Haha! once in control, he's boss!
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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

Recapped the output board. Still diminished output on the right
Contacts all look good
Chopstick of destiny did not help

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Re: Definitely a guitar thread not keyboard related

Post by nztim »

StrummersOfThunder wrote: Thu Feb 22, 2024 7:55 am And on the board ive noted 100uF 25v caps with bulging ends (Jeremy)

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I see in this photo an N5532 opamp. I have had them fail on me before in headphone amps where they use them as a stereo opamp rather that gain staging them, which resulted in one dim or non existent channel. Would have see a schematic of this layout to know how they used it.
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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

nztim wrote: Fri Feb 23, 2024 1:55 pm
StrummersOfThunder wrote: Thu Feb 22, 2024 7:55 am And on the board ive noted 100uF 25v caps with bulging ends (Jeremy)

Image
I see in this photo an N5532 opamp. I have had them fail on me before in headphone amps where they use them as a stereo opamp rather that gain staging them, which resulted in one dim or non existent channel. Would have see a schematic of this layout to know how they used it.
Interesting , that’s exactly the symptom
I have a schematic hang on ….

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Re: Definitely a guitar thread not keyboard related

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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

nztim wrote: Fri Feb 23, 2024 1:55 pm
StrummersOfThunder wrote: Thu Feb 22, 2024 7:55 am And on the board ive noted 100uF 25v caps with bulging ends (Jeremy)

Image
I see in this photo an N5532 opamp. I have had them fail on me before in headphone amps where they use them as a stereo opamp rather that gain staging them, which resulted in one dim or non existent channel. Would have see a schematic of this layout to know how they used it.
Any thoughts ?

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Re: Definitely a guitar thread not keyboard related

Post by nztim »

Sorry for delay, weekend chores. Looking at the schematic it looks like they’re set up as gain staged, is there a volume difference through the unbalanced output? As that looks like it bypasses those op amps. If it’s the same through them then op amps aren’t the culprit. I see that all the audio comes off the master volume. Have you given that a dose of contact cleaner?
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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

nztim wrote: Sat Feb 24, 2024 5:51 pm Sorry for delay, weekend chores. Looking at the schematic it looks like they’re set up as gain staged, is there a volume difference through the unbalanced output? As that looks like it bypasses those op amps. If it’s the same through them then op amps aren’t the culprit. I see that all the audio comes off the master volume. Have you given that a dose of contact cleaner?
Same out of the 1/4 jacks yes
No I haven’t tried co text cleaner , can give it a whirl now and report back

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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

Low output on the left out of unbalanced
Also there post contact cleansing

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Re: Definitely a guitar thread not keyboard related

Post by nztim »

Ah what a pain. I’ll keep looking over and see what else I can spot but prob best to have someone with a multi meter look at it.
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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

nztim wrote: Sat Feb 24, 2024 8:38 pm Ah what a pain. I’ll keep looking over and see what else I can spot but prob best to have someone with a multi meter look at it.
Thanks
I have a multimeter just a bit lost as to where to start
Guess I’ll just check voltages along the signal path ?

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Re: Definitely a guitar thread not keyboard related

Post by StrummersOfThunder »

Do you think I need to try and recap the power board ?

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Re: Definitely a guitar thread not keyboard related

Post by nztim »

I would imagine that if the power supply was acting up the problems would be more than just a dip in one channel. Its gunna be pretty hard to diagnose anything without actually looking at the unit. I did a bit of googling, and they seem to come up with the same issue of needing a recap on the output board. So if you've done that and your still getting unbalance outputs it might be a tech jobby.

There is no silly pan options or anything in the unit are there? Or factory reset? just to see if that changes anything.
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