elektroivo
Well-known member
APHEX 109 schematics needed.... pls, help! ??? :'(
APHEX 109 EQ
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strangeandbouncy
Well-known member
Hi,
good luck! I never found them either! Wonderful eq for the money( I paid £10!!)
Kindest regards,
ANdyP
good luck! I never found them either! Wonderful eq for the money( I paid £10!!)
Kindest regards,
ANdyP
elektroivo
Well-known member
I know taht's great EQ.... that why i'm trying to repair it 
well, thats' pretty discouraging.... it seems to me that i'lll have to draw schematic manualy..... :
well, thats' pretty discouraging.... it seems to me that i'lll have to draw schematic manualy..... :
I think there are different PCB versions. Not radically different, but I have two of those units (1995 and 1996, I think; one US, one Japan import). One of them has a couple of extra cables on the underside of the PCB. Those cables look factory installed (probably extra ground), but not 100% sure cos I got both units used.
The vacuum tubes too are different in the two units (maybe someone swapped it). The pots on one unit are all scratchy to the point of being almost useless and on the other unit one pot got totally stuck (always meant to replace all of them, but...).
Anyway, crosstalk has never been all that fantastic with this eq in the first place. Still I sometimes like them for that exclusive "toob-essence" sound when tracking, but hardly ever use them as eqs. I'm pretty sure there's a patent on that "essence" thing. And there's also an Aphex white paper with a detailed schematic of the tube circuit somewhere on the net, if that's where your unit is at fault. Other than that...
The vacuum tubes too are different in the two units (maybe someone swapped it). The pots on one unit are all scratchy to the point of being almost useless and on the other unit one pot got totally stuck (always meant to replace all of them, but...).
Anyway, crosstalk has never been all that fantastic with this eq in the first place. Still I sometimes like them for that exclusive "toob-essence" sound when tracking, but hardly ever use them as eqs. I'm pretty sure there's a patent on that "essence" thing. And there's also an Aphex white paper with a detailed schematic of the tube circuit somewhere on the net, if that's where your unit is at fault. Other than that...
StephenGiles
Well-known member
It always been hard to come by Aphex schematics. Back in the 1980s I was driving quite close to the UK main agents for Aphex somewhere around Stevenage in the UK. I took a detour, visited the main agents and asked for a service manual for the Aural Exciter B, which a very kind lady gave me - the service manual that is ;D
elektroivo
Well-known member
Thanx Script for info. my problem is somewhere oround the tube, but not the tube itself. last OPAMP stage output is dead, but OPAMP is fully functional, like i'm having some leakage in tube circuit. problem is same in both channels. I've tried to find that white paper you've mentioned, but with no results :-(
elektroivo
Well-known member
problem solved!
I've wrongly assumed that problem was in tube circuit.
OPAMP stage was not dead... it is actualy voltage to current converter. (I've figuded that out after I've drawn schematic of that circuit).
Script, thanks again for that whitepaper about Reflected Plate Amplifier... you've saved me a lot of time
PCB traces are very thin. beacouse of that there was large resistance introduced in signal and voltage lines to tube circuit. voltage for tube circuit measured at PSU vas at first 3.2V, after bypasing traces with thin wire, i've got healhy 45v, but at the tube, there was still only 1.8 V. after bypasing few more traces, and replacing few leaky caps, i've got 45V at tube, and device started to work. switches and pots needed cleaning and lube.
I've wrongly assumed that problem was in tube circuit.
OPAMP stage was not dead... it is actualy voltage to current converter. (I've figuded that out after I've drawn schematic of that circuit).
Script, thanks again for that whitepaper about Reflected Plate Amplifier... you've saved me a lot of time
PCB traces are very thin. beacouse of that there was large resistance introduced in signal and voltage lines to tube circuit. voltage for tube circuit measured at PSU vas at first 3.2V, after bypasing traces with thin wire, i've got healhy 45v, but at the tube, there was still only 1.8 V. after bypasing few more traces, and replacing few leaky caps, i've got 45V at tube, and device started to work. switches and pots needed cleaning and lube.
Sorry to bring back an ancient thread. Found one of these in the trash (actually in the trash) and R143 and R142 are blown up in smoke. I'm assuming these are the same values as R243 and R242 based on the location and surrounding components but would like to know what exactly these resistors do before blindly replacing them. Having lot of difficulty finding a schematic.
The schematic for the 107 preamp is in the Technical Docs section here. I also just uploaded a white paper of the Tubessence circuit.
https://groupdiy.com/threads/aphex.45247/#post-1039150
I have never seen the 109 or it's drawings, but I hope these help.
https://groupdiy.com/threads/aphex.45247/#post-1039150
I have never seen the 109 or it's drawings, but I hope these help.
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