Definitely a guitar thread not keyboard related
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Re: Definitely a guitar thread not keyboard related
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.
Not a Korg like yours I know.
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Re: Definitely a guitar thread not keyboard related
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
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
Haha! once in control, he's boss!
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Re: Definitely a guitar thread not keyboard related
Recapped the output board. Still diminished output on the right
Contacts all look good
Chopstick of destiny did not help
Contacts all look good
Chopstick of destiny did not help
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Re: Definitely a guitar thread not keyboard related
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.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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Re: Definitely a guitar thread not keyboard related
Interesting , that’s exactly the symptomnztim wrote: ↑Fri Feb 23, 2024 1:55 pmI 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.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 have a schematic hang on ….
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Re: Definitely a guitar thread not keyboard related
Schematic in this service manual:
https://t-45m.net/i/sv1/_manuals/SV1-ServiceManual.pdf
https://t-45m.net/i/sv1/_manuals/SV1-ServiceManual.pdf
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Re: Definitely a guitar thread not keyboard related
Any thoughts ?nztim wrote: ↑Fri Feb 23, 2024 1:55 pmI 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.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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Re: Definitely a guitar thread not keyboard related
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
Same out of the 1/4 jacks yesnztim 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?
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
Low output on the left out of unbalanced
Also there post contact cleansing
Also there post contact cleansing
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Re: Definitely a guitar thread not keyboard related
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
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
Do you think I need to try and recap the power board ?
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Re: Definitely a guitar thread not keyboard related
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.
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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