Any techs/builders with a LAney AOR 6 knob MV schematic???

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Kapo_Polenton

Kapo_Polenton

Well-known member
I've had this amp over two years... messing around with this f_cker. Ripped the board out long ago and replaced with a PTP. It has to be wired like a 100 watter in the rectifier section and that is fine but i don't get why i get low buzzy distortion. Something is off in the rectifier section and i need the original schematic. All the ones on line are 8 knobbies, series II with footswitches.. i need the down and dirty original MV six knobbie amp with push pull pots on tone controls. Can anyone ease my frustration? It is driving me insane. Been up and down the amp and everything checks out... I've searched all across the net... nadda.Comparing the board that came out with what i have in there, I'm left thinking here is no bias feed resistor. That doesn't seem like it should be so i want to check the schematic as i might have pillaged the PCB for parts over time and just don't remember.

Help a drowning brutha out!
 
No it's the 6 knob AOR 50 watter i was just referencing the 100 watt because the rectifier section needs to be built similar to the bridge in a 100 watt Marshall because of how the bias supply runs to the standby switch then back to the board. Either way i am now wondering why the laney's have a configuration of 8 diodes and Marshalls only use 4. I might actually be using wrong value diodes and that is all I am left being able to guess.
 
Multiple diodes in series will double the reverse voltage breakdown capabilities of the diodes without much adverse affect on the forward voltage. Normally you can put resistors in parallel with the diodes to balance the voltage drop across them much as you do with RC designs in the filtering section for capacitor banks. Sometimes in consumer quality gear you also see caps in parallel with the diodes to slow the forward breakover voltage.

And yeah i dont have the 50W one, although have you tried searching again with google? I am pretty sure i found this one off of the net, you shouldnt have to much trouble.
 
studio289":2k2mawyu said:
Have you been here yet?
http://www.laney-posse.co.uk/theposse/index.php
Click to expand...

Bam! and there it was... linked back to the metro forum of all places (where i also was doing thread searches) but who cares, I got this little bastard and will save it for reference. Thanks for the help guys.

If anyone else is looking, here's the old school jcm800 clone: http://forum.metroamp.com/download/file ... 0f420d0c12 (which really doesn't sound as good as a JCM800) though i would prob have been better off just modding the PCB and sticking it back in. Anyway, I'm loaded up with sozos now so should be good if i can get it up and running.
 
glpg80 said:
Multiple diodes in series will double the reverse voltage breakdown capabilities of the diodes without much adverse affect on the forward voltage. Normally you can put resistors in parallel with the diodes to balance the voltage drop across them much as you do with RC designs in the filtering section for capacitor banks. Sometimes in consumer quality gear you also see caps in parallel with the diodes to slow the forward breakover voltage.

Thats some sexy talk there old man... :D

THIS is why I love this place... (Although I have NO IDEA of what your talking about...) :lol: :LOL:
Click to expand...
 
you know those things are actually killer stock. you just have to be able to dime it.
 
Well yes and no.. i did use it attenuated and the trick was actually to pull the bass boost but set it to zero BUT the distortion was still rather gritty and buzzy even with warm preamp tubes. Knowing the bit i do now though, i would have just swapped a few parts and rocked it but back when i gutted it i was cork sniffing so i just HAD to have sozos and a PTP. So now, I want this working just to see what it comes out as. Then maybe i'll throw the PCB back in with a mod or two down the line just to see how much diff there really is.
 
Ok attached is where I am at and I am lost. With the Laney trannies , the rectifier section needs to be wired like a 100 watter (which i did). So now I am confused, the 100 and 50 watters differ somewhat in how the choke gets wired. Seems to me mine is wired more like a 100 watter. Can anyone make heads or tales of my amateur work?

top of the screen: (beside bias trim pot on the two 8.2-10k resistors in series)

blue wire goes to filter cap +
white goes to v4 output tube socket
red is choke

bottom of screen

blue wire goes to power/voltage selector
thick black is transformer lead
thin black is other side of choke

Could this be the issue why i am not getting the output i require? If wired like a 100 watter here this might explain why the volume is so low.. would it not? I don't want to go f-cking around anymore unless i am certain.

PS- Yes I am aware it is not pretty wiring but neither is my Traynor and that thing rocks now!
 

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bump..don't let the spaghetti mix fool you, it will eventually rock! (I hope)
 
Troubleshooting is not done with pictures over forums - it is done with a voltmeter and lead tracing. You're going to need to spend some time to give us measurements or collect measurements from certain points - first making sure the tubes are biased accordingly and second making sure you have not made a mistake with your PTP board.

The rectification section of the board is straight forward - do you have an o-scope you can measure the output to see if you're getting the correct wave form?
 
People that don't know shouldn't be giving any advice. I know everyone means well, but if you give someone advice without actually knowing what the hell you're talking about or thinking it thru to be sure you are saying the correct thing you're not helping. One of these days someone is going to get hurt bad listening to internet experts.

In reading his post there's enough to know he's in over his head and shouldn't be turning on the amp for measurements. The voltage selector switch wiring is part of the power transformer primary and should be nowhere near the high voltage secondary side or after rectification.

The 100 watt amp uses a center tapped winding for B+, the 50 watt does not so they can't be wired the same.

Jerry
 

Attachments

JerryP":1gfd7oqg said:
People that don't know shouldn't be giving any advice. I know everyone means well, but if you give someone advice without actually knowing what the hell you're talking about or thinking it thru to be sure you are saying the correct thing you're not helping. One of these days someone is going to get hurt bad listening to internet experts.

In reading his post there's enough to know he's in over his head and shouldn't be turning on the amp for measurements. The voltage selector switch wiring is part of the power transformer primary and should be nowhere near the high voltage secondary side or after rectification.

The 100 watt amp uses a center tapped winding for B+, the 50 watt does not so they can't be wired the same.

Jerry
Click to expand...

Did not even cross my mind the OT is not center tapped on the 50W version. You're right. He would need to use the center tapped version, wire it with one tube on each leg and then remove the 16ohm tap or terminate it properly since the primary impedance would then be doubled.

Jerry do not be an asshole. The only person out for blood in this topic is you. I did not have the schematic, and neither did the OP. Get your head out of your ass. There is no call for being a dick over a forum simply because two people did not catch the same mistake.

The recommendations for measuring voltage are assuming the circuit is working and functionally sound. If you get hurt using practices that are not correct in troubleshooting your own circuit you have no business poking around them to begin with.
 
No need to argue on here fellas, I appreciate everyone's assistance thus far so I have no problem entertaining ideas. Am I over my head? Somewhat, but I spent today looking at the right schematic for the amp and the only thing I can see is that I have my red and black choke wires reversed in terms of where they connect on the schematic but I am not entirely sure that this would be a factor seeing as there are plenty of chokes I thought where this is not an issue. Second, my bias/trim pot wiring. I am thinking of looking at that more closely again as I might have made a mistake somewhere.

Voltage wise, all preamp and output tubes checked out within spec of what an 800 would have but slightly lower as the transformer doesn't seem to run as high. (397 plate voltage) I don't have a scope as this is not something I do full time. I usually just alter preamp sections of my amps for tinkering and learning. Maybe i was feeling ambitious with this one.

In reading his post there's enough to know he's in over his head and shouldn't be turning on the amp for measurements. The voltage selector switch wiring is part of the power transformer primary and should be nowhere near the high voltage secondary side or after rectification.

The 100 watt amp uses a center tapped winding for B+, the 50 watt does not so they can't be wired the same.
Click to expand...

Why don't you tell me what you really think? lol :scared: I am aware of where the voltages that kill are. I also incorrectly indicated that one of the wires was headed into the voltage selector switch when i should have indicated that it was run in that general direction and appears to be run to the fuse.(where it should be) When you were learning about amps, did you know everything about the circuit? I have no plans of becoming a Friedman or other. I just wanted an amp i could tinker with and try diff mods. That' why the PTP went in.

I also double checked my wiring to the power section from the transformer in the schematic and that is how I have it run. brown to standby and to rectifier, orange to ground and to diode on the board.
 
You cannot connect a choke backwards.

What OT are you using or trying to use?
 
Everything stock that came with the amp. (or do you want the choke/transformer model numbers?)The choke might very well be the issue then if comparing the schematic to what I have wired.
 
glpg80":1p0affxs said:
JerryP":1p0affxs said:
People that don't know shouldn't be giving any advice. I know everyone means well, but if you give someone advice without actually knowing what the hell you're talking about or thinking it thru to be sure you are saying the correct thing you're not helping. One of these days someone is going to get hurt bad listening to internet experts.

In reading his post there's enough to know he's in over his head and shouldn't be turning on the amp for measurements. The voltage selector switch wiring is part of the power transformer primary and should be nowhere near the high voltage secondary side or after rectification.

The 100 watt amp uses a center tapped winding for B+, the 50 watt does not so they can't be wired the same.

Jerry
Click to expand...

Did not even cross my mind the OT is not center tapped on the 50W version. You're right. He would need to use the center tapped version, wire it with one tube on each leg and then remove the 16ohm tap or terminate it properly since the primary impedance would then be doubled.

Jerry do not be an asshole. The only person out for blood in this topic is you. I did not have the schematic, and neither did the OP. Get your head out of your ass. There is no call for being a dick over a forum simply because two people did not catch the same mistake.

The recommendations for measuring voltage are assuming the circuit is working and functionally sound. If you get hurt using practices that are not correct in troubleshooting your own circuit you have no business poking around them to begin with.
Click to expand...


Out for blood? No, just trying to help the guy not get hurt. I have seen you shoot from the hip with more incorrect information all across the web than anyone else in the world! You are wrong more often than not and you are going to get someone hurt one of these days.

Re-read what you typed above, didn't cross your mind the OT was center tapped? It's a push/pull circuit, they all are, they have to be. We were talking about the PT. O and P are next to each other and it could certainly be a simple mistake, but you need to read your posts before you hit enter if you are going to send someone into an amp with 400-500 volts at their finger tips.
Jerry
 
Kapo_Polenton":z85g7z5k said:
No need to argue on here fellas, I appreciate everyone's assistance thus far so I have no problem entertaining ideas. Am I over my head? Somewhat, but I spent today looking at the right schematic for the amp and the only thing I can see is that I have my red and black choke wires reversed in terms of where they connect on the schematic but I am not entirely sure that this would be a factor seeing as there are plenty of chokes I thought where this is not an issue. Second, my bias/trim pot wiring. I am thinking of looking at that more closely again as I might have made a mistake somewhere.

Voltage wise, all preamp and output tubes checked out within spec of what an 800 would have but slightly lower as the transformer doesn't seem to run as high. (397 plate voltage) I don't have a scope as this is not something I do full time. I usually just alter preamp sections of my amps for tinkering and learning. Maybe i was feeling ambitious with this one.

In reading his post there's enough to know he's in over his head and shouldn't be turning on the amp for measurements. The voltage selector switch wiring is part of the power transformer primary and should be nowhere near the high voltage secondary side or after rectification.

The 100 watt amp uses a center tapped winding for B+, the 50 watt does not so they can't be wired the same.
Click to expand...

Why don't you tell me what you really think? lol :scared: I am aware of where the voltages that kill are. I also incorrectly indicated that one of the wires was headed into the voltage selector switch when i should have indicated that it was run in that general direction and appears to be run to the fuse.(where it should be) When you were learning about amps, did you know everything about the circuit? I have no plans of becoming a Friedman or other. I just wanted an amp i could tinker with and try diff mods. That' why the PTP went in.

I also double checked my wiring to the power section from the transformer in the schematic and that is how I have it run. brown to standby and to rectifier, orange to ground and to diode on the board.
Click to expand...


Do you have volume or is the overall volume output of the amp low?
Is it always buzzy like a fuzz box with no clean no matter the settings?
If you have good volume and it will clean up I would look at where things are grounded.
Jerry
 
Do you have volume or is the overall volume output of the amp low?
Is it always buzzy like a fuzz box with no clean no matter the settings?
If you have good volume and it will clean up I would look at where things are grounded.
Jerry
Click to expand...

Overall output of the amp is low, i can back off the gain to clean it up but it gets pretty splatty and fuzzy bit past noon on preamp dial.

The low input remains relatively clean as it should but also suffers from low volume.

So really the issue is overall low volume (even with master cranked) and ugly distortion.

output tubes are new and bias correctly at around 43 mA (6CA7).

I checked for continuity for all my grounds too and it all checked out. I suppose a cold solder joint on a ground could be an issue as well.

So just to clarify, are you guys saying that a choke's(essentially acting somewhat like a resistor from my understanding) leads do NOT matter? Some chokes have two black leads for example.. mine has a red/black as per the schematic and i have them swapped in my build vs where they are indicated as going on the schematic.
 
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