CoolCat
Well-known member
heres one with No leakage...go figure?
CoolCat
Well-known member
this one has leakage? how strange....is this even a real problem or a "loose QC tolerance "
25:35....and he has Channel 2 completely Off, and Channel 1 only but both LED' show dual channel....is what Im seeing.
25:35....and he has Channel 2 completely Off, and Channel 1 only but both LED' show dual channel....is what Im seeing.
Steenamaroo
...
Yeah, there's plenty of videos showing the unused side being completely dark,
so it's not a design or from-factory issue.
Common fault, though? Seems like.
"Seems the design doesn't keep the unused side OFF"
No, the design does. Some failure is happening.
"Why didn't they just have two separate Ch1 and Ch2...? why tie Ch1 - Q1 to Ch2- Q2?"
Because the controller dictating which LEDs should light up (not which bank...how many) has 8 channels.
To do it your way requires a 16 channel chip, or two chips... = $$
"I don't understand why Q1 is connected to Q2 input?"
Q101 opens and closes rapidly.
Doing so closes and opens Q102 rapidly.
Q101 being open lights ch1 LEDs and closes Q102.
Q101 being closed kills ch1 LEDs and opens Q102.
It's just two switches - one dependent on the other.
so it's not a design or from-factory issue.
Common fault, though? Seems like.
"Seems the design doesn't keep the unused side OFF"
No, the design does. Some failure is happening.
"Why didn't they just have two separate Ch1 and Ch2...? why tie Ch1 - Q1 to Ch2- Q2?"
Because the controller dictating which LEDs should light up (not which bank...how many) has 8 channels.
To do it your way requires a 16 channel chip, or two chips... = $$
"I don't understand why Q1 is connected to Q2 input?"
Q101 opens and closes rapidly.
Doing so closes and opens Q102 rapidly.
Q101 being open lights ch1 LEDs and closes Q102.
Q101 being closed kills ch1 LEDs and opens Q102.
It's just two switches - one dependent on the other.
CoolCat
Well-known member
This makes sense, thanks. good explanation imo.
ov...Q1 passes to turn on LED
5v...Q1 closed and turns off LED...because its tied to Q2 this opposite effect opens Q2 a little bit and weak LED are ON.
happening really fast so , yeah, good refresh on basic Transistor workings.
so/? when both channels are receiving Sound/Signal....the bleed is still happening on the display, but the Active is so much brighter , the "ghost" isnt seen, I suppose.
this is a good thing really because I don't care if its cosmetic, and Im only concerned something is failing and will continue to get worse rapidly.
it seems there's a bunch of leakage ART MPAII out there but most owners probably don't care.
Would reducing the 5V weaken the circuit enough to not show enough leakage to turn on the unused channel?
Steenamaroo
...
Not quite...I'm describing how the circuit works properly...Not the failure.
Q1 closing fully opens Q2.
Q1 opening fully closes Q2.
There's only ever one bank of LEDs illuminated at any given time.
That is the intended function of the circuit.
(To make matters more complicated I've used the terms "open" and "closed" backwards quite a lot.
)The fact that you get full bright LEDs on both channels when you're meant to says that the transistors are allowing current when they should.
So that means current is getting around, or through, both transistors when it should not.
CH1 is fully lit when it's meant to be, and CH2 is partially lit at the same time...It should not be.
(and vice versa)
I don't see a common way around so either both transistors are failing to fully block current, or the signal controlling them is not doing what it's meant to do.
CoolCat
Well-known member
very strange, so by design it looks right, ok.
but by operation the circuit is leaking, both transistors partially On , with V at the collector.
I wonder if Brand New units have this odd- "ghost" LED leakage.
but by operation the circuit is leaking, both transistors partially On , with V at the collector.
I wonder if Brand New units have this odd- "ghost" LED leakage.
Steenamaroo
...
Yes; something has failed or gone out of spec causing this issue.
"I wonder if Brand New units have this odd- "ghost" LED leakage"
The one in this video is perfectly fine, plus your own video in post #41.
"I wonder if Brand New units have this odd- "ghost" LED leakage"
The one in this video is perfectly fine, plus your own video in post #41.
Papanate
Well-known member
I haven’t read the whole thread so forgive this intrusion : Is the leakage on the LEDs or it is also in the Audio between Channels?
CoolCat
Well-known member
Its on the LEDS only.
from a general YouTube videos posted, you can see the "leakage""ghost" LED discussed....some don't have this leakage, but an interesting amount of MPAII in the videos have it.
the TechSupport- Yorkville (owns ART)....replied this morning they are confident its a flash-chip but haven't got me a quote and don't have any in stock. (easy to swap out)
The simulation of the circuit, cleverly done by Steenamaroo shows its more likely a leakage in the transistors/ display circuit. (transistor replacement will take disassembly and soldering but cheap! )
there's a strange Mid/Side mechanical switch but seems the data shows if its that it would leak to the Outputs and seen in the DAW...which this LED leakage is not seen in the DAW tracks. So again it seems purely a cosmetic- issue.
My concern is if its just cosmetic I don't care at all, but if its a failing part that might continue to fail and worse breakdown, I can return this item and don't want to buy a dead horse.
Its been fun learning about transistors and the MPAII a bit more in-depth too imo..
from a general YouTube videos posted, you can see the "leakage""ghost" LED discussed....some don't have this leakage, but an interesting amount of MPAII in the videos have it.
the TechSupport- Yorkville (owns ART)....replied this morning they are confident its a flash-chip but haven't got me a quote and don't have any in stock. (easy to swap out)
The simulation of the circuit, cleverly done by Steenamaroo shows its more likely a leakage in the transistors/ display circuit. (transistor replacement will take disassembly and soldering but cheap! )
there's a strange Mid/Side mechanical switch but seems the data shows if its that it would leak to the Outputs and seen in the DAW...which this LED leakage is not seen in the DAW tracks. So again it seems purely a cosmetic- issue.
My concern is if its just cosmetic I don't care at all, but if its a failing part that might continue to fail and worse breakdown, I can return this item and don't want to buy a dead horse.
Its been fun learning about transistors and the MPAII a bit more in-depth too imo..
CoolCat
Well-known member
ok. troubleshooting....left hanging.
Another MPAII came up at $239 at GC so I grabbed it and its 100% working on the LEDs.
So basically the "$199 unit with LED ghost" will get returned.
Im was so tempted to swap PROM chips in a tech-head nerd way..just to see if it fixes the other one but its more complicated again because one unit has a 2002-2008 motherboard and a different ID on the Chip, where the other MPAII has a 2002-2016 motherboard and different Chip ID....arrrrgg!
if the Flash chips had matched I probably would have tried popping it in, to see if it is in fact the Chip....but as it is...I'll leave it as is.
Ill return the LED- $199 unit to GC. Keep this MPAII- and VLA combo.
This one also has matching colors to the VLA VU meters, "orangeish" glow....did Art intentionally vary the LED colors too or is it another oddity?
The versions of the Chip per Google Search, are aimed at the DIGITAL aspect functions...and supposedly are "swappable".
I asked AI "what are the differences in versions of the U409 chip?"
AI Overview
In the schematic and service manual for the ART Pro MPA II, the component labeled U409 is not an audio operational amplifier (op-amp) or part of the analog signal path. Instead, it is an 8-bit microcontroller chip (specifically, the MC68HRC908JK1P in a DIP-20 package).
Function of the U409 Chip
Because U409 is a microcontroller, it does not process or pass audio signals. Its sole responsibility is system logic and control functionality, which includes: [1]
then AI said some off the wall....crap....and I corrected AI, saying these two units have the U409 CHIP and both units do NOT have the
Digital Ouput. AI thanked me for correcting it and offered this...
Another MPAII came up at $239 at GC so I grabbed it and its 100% working on the LEDs.
So basically the "$199 unit with LED ghost" will get returned.
Im was so tempted to swap PROM chips in a tech-head nerd way..just to see if it fixes the other one but its more complicated again because one unit has a 2002-2008 motherboard and a different ID on the Chip, where the other MPAII has a 2002-2016 motherboard and different Chip ID....arrrrgg!
if the Flash chips had matched I probably would have tried popping it in, to see if it is in fact the Chip....but as it is...I'll leave it as is.
Ill return the LED- $199 unit to GC. Keep this MPAII- and VLA combo.
This one also has matching colors to the VLA VU meters, "orangeish" glow....did Art intentionally vary the LED colors too or is it another oddity?
The versions of the Chip per Google Search, are aimed at the DIGITAL aspect functions...and supposedly are "swappable".
I asked AI "what are the differences in versions of the U409 chip?"
AI Overview
In the schematic and service manual for the ART Pro MPA II, the component labeled U409 is not an audio operational amplifier (op-amp) or part of the analog signal path. Instead, it is an 8-bit microcontroller chip (specifically, the MC68HRC908JK1P in a DIP-20 package).
Function of the U409 Chip
Because U409 is a microcontroller, it does not process or pass audio signals. Its sole responsibility is system logic and control functionality, which includes: [1]
- Managing the backlit function switches.
- Driving the LED meters (like the Tube Warmth display).
- Controlling system startup timing, logic state selections (such as the Mid/Side matrix or Stereo/Dual mono routing), and instrument input auto-selection.
then AI said some off the wall....crap....and I corrected AI, saying these two units have the U409 CHIP and both units do NOT have the
Digital Ouput. AI thanked me for correcting it and offered this...
CoolCat
Well-known member
well, I couldn't resist and swapped the chips.
it didn't work at all, so AI is wrong saying the chips are interchangeable. Because it didn't go through the power up sequence and froze.
luckily the flash-prom-chips were put back into their original units and the $239 unit works fine as it did....the other one still works fine but has the ghost-leak .$199 Unit will get returned.
thanks for the inputs and thanks for the help as always !!
it didn't work at all, so AI is wrong saying the chips are interchangeable. Because it didn't go through the power up sequence and froze.
luckily the flash-prom-chips were put back into their original units and the $239 unit works fine as it did....the other one still works fine but has the ghost-leak .$199 Unit will get returned.
thanks for the inputs and thanks for the help as always !!
Steenamaroo
...
Absolute shocker.
Honestly, that's the value in this thread.
The more people learn not to blindly trust AI the better.
Health to enjoy!
CoolCat
Well-known member
yeah I left out when I asked AI "why did ART have different versions of the Chip?"
AI calculated- speed searching...and said the Version changes were only for the MPAII Digital Units...not the Analog MPAII...
then AI added " the Analog versions of the MPAII don't even have chip u409"
of course that was wrong too.
I agree AI has to be used with great skepticism.
It is a faster search engine it seems and it does have some things right, but its the old "garbage IN, garbage OUT" syndrome. If AI is including wrong information from some site or forum then its details are incorrect too.
Anyway- it was interesting and thanks for the Electronic Circuit info, it makes sense in the leakage part of the circuit.
Im assuming Ill get a quote for the PROM chip and will guess $70~$100 total. Which on a $199 unit a No-Go.
The MPA/VLA VU lights are $20, the whole assembly $75. Typical for any brand.
Reading MPA in general there must be a huge amount of them sold. So more posts.
I worked in a TV chip group and sometimes went to Marketing meetings etc...and when our expensive HDTV were $10,000, $12,000 the people buying them were few.
As engineering worked at making it cheaper cheaper cheaper..to junk level....the quantity of sales skyrocketed as the HDTV went to $1000 or less.
So assuming ART MPA and its gear is Budget....price would sell a bunch of them.
Compared to like a ISA Console there were only what? eight of them ever made and sold. Focusrite stopped selling ISA 110, 430, 220...and kept the ISA One, Two and 428,828 I think. Great products but too expensive and not enough profit.
Rode dropped their Classic Tube mic line....I guess as a business it just wasn't a product making profit even though its probably the best product they made, they still dropped it? weird....imo.
AI Mode Search says company's don't release the numbers but in general MPA selling 2,000- 5,000 units per year, at a 15 yr run, 35,000 -75,000 units estimated.
Im impressed with the price and the sound, the layout is really well done....the vari-Impedance and the HPF, the Stereo or Mono and MidSide I wont use....and I love VU meters....gets the old school glow....of Analog.
AI calculated- speed searching...and said the Version changes were only for the MPAII Digital Units...not the Analog MPAII...
then AI added " the Analog versions of the MPAII don't even have chip u409"
of course that was wrong too.
I agree AI has to be used with great skepticism.
It is a faster search engine it seems and it does have some things right, but its the old "garbage IN, garbage OUT" syndrome. If AI is including wrong information from some site or forum then its details are incorrect too.
Anyway- it was interesting and thanks for the Electronic Circuit info, it makes sense in the leakage part of the circuit.
Im assuming Ill get a quote for the PROM chip and will guess $70~$100 total. Which on a $199 unit a No-Go.
The MPA/VLA VU lights are $20, the whole assembly $75. Typical for any brand.
Reading MPA in general there must be a huge amount of them sold. So more posts.
I worked in a TV chip group and sometimes went to Marketing meetings etc...and when our expensive HDTV were $10,000, $12,000 the people buying them were few.
As engineering worked at making it cheaper cheaper cheaper..to junk level....the quantity of sales skyrocketed as the HDTV went to $1000 or less.
So assuming ART MPA and its gear is Budget....price would sell a bunch of them.
Compared to like a ISA Console there were only what? eight of them ever made and sold. Focusrite stopped selling ISA 110, 430, 220...and kept the ISA One, Two and 428,828 I think. Great products but too expensive and not enough profit.
Rode dropped their Classic Tube mic line....I guess as a business it just wasn't a product making profit even though its probably the best product they made, they still dropped it? weird....imo.
AI Mode Search says company's don't release the numbers but in general MPA selling 2,000- 5,000 units per year, at a 15 yr run, 35,000 -75,000 units estimated.
Im impressed with the price and the sound, the layout is really well done....the vari-Impedance and the HPF, the Stereo or Mono and MidSide I wont use....and I love VU meters....gets the old school glow....of Analog.
CoolCat
Well-known member
add for anyone's interest -
the Chip price is $10.
Yorkville tech support didn't think the problem would get worse.
the Chip price is $10.
Yorkville tech support didn't think the problem would get worse.
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