People in general seem to be unaware of product quality, or just don't give a damn.
I repaired a smaller wattage variant of that Tandberg a few years ago.
I think it was a 25 or 30 watt/channel version, I forget the actual model number.
It didn't sound bad, for what it was, and the customer (an optometrist) was so thrilled with it that he offered me (after paying my hefty fee of course) a discount on eyeglasses, should I need a new pair someday.
He then purchased a "for sale" Pioneer upper model cassette deck that I had on display in the shop.
It had an "auto load" cassette door - you drop the cassette in, and the motor closes the door.
What a pleased customer he was!
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I built up a new usb scope.
Just got garbage on the pc screen.
So, the microcontroller must be working as USB data is being sent.
The micro just connects to the A2D so that must be the problem.
The A2D is on a daughterboard and one pin wasnt soldered.
Fixed that but still the same.
So must be a pin on the A2D with a bad joint.
Reflowed the pins and still the same.
Getting ready to give up.
One last time I re-soldered all the pins slowly to ensure good soldered joints.
This time it burst into life.
Probably a dirty pcb pad. So next time will give it a good clean before soldering.
Just got garbage on the pc screen.
So, the microcontroller must be working as USB data is being sent.
The micro just connects to the A2D so that must be the problem.
The A2D is on a daughterboard and one pin wasnt soldered.
Fixed that but still the same.
So must be a pin on the A2D with a bad joint.
Reflowed the pins and still the same.
Getting ready to give up.
One last time I re-soldered all the pins slowly to ensure good soldered joints.
This time it burst into life.
Probably a dirty pcb pad. So next time will give it a good clean before soldering.
I've not seen one of these come apart before, but you can just imagine the racket it creates when it happens while running at full tilt.
Disintegrated Friday evening; I had it out Saturday morning in time to make the rounds of the supply houses where I have commercial accounts. None of them stocked anything this big.
Had to order it in, replacement should be here today or tomorrow. Surprisingly expensive for a bunch of cheap stampings pressed together. Last week of August, first week or two of September are the hottest time of the year here, so everyone went to the lake but me - I have business here every day this week.
edit: interestingly, the sole remaining U.S. factory for Rheem air conditioners is right here in town - but I can't get the parts here, I have to order them in!
Disintegrated Friday evening; I had it out Saturday morning in time to make the rounds of the supply houses where I have commercial accounts. None of them stocked anything this big.
Had to order it in, replacement should be here today or tomorrow. Surprisingly expensive for a bunch of cheap stampings pressed together. Last week of August, first week or two of September are the hottest time of the year here, so everyone went to the lake but me - I have business here every day this week.
edit: interestingly, the sole remaining U.S. factory for Rheem air conditioners is right here in town - but I can't get the parts here, I have to order them in!
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I upgraded an op amp in my circuit to a faster op amp with better slew rate.
I then noticed the input was no longer pulled down to zero volts.
It was sat just below a volt.
I reread the data sheet on the op amp and it has a input current of 1uA.
So that in combination with my 1 meg input resistor gives the 1 volt.
So added a 10 meg resistor from input to -ve rail and that cancelled out the voltage.
I then noticed the input was no longer pulled down to zero volts.
It was sat just below a volt.
I reread the data sheet on the op amp and it has a input current of 1uA.
So that in combination with my 1 meg input resistor gives the 1 volt.
So added a 10 meg resistor from input to -ve rail and that cancelled out the voltage.
Hi Nigel,
That must have been annoying, but you got it!
Hi Chris,
1.) Why was the 4136 Op Amp ever designed and sold?
2.) Why does the 4136 Op Amp have it's very own non-standard pin out?
I'm not a fan of most of Bob Carver's auxiliary circuits, and the way he names them. However, his amplifier designs are brilliant. So are his auxiliary circuits if you look at what they are attempting to do. There is a high cost to pay in the form of lots of op amps and ceramic capacitors.
-Chris
That must have been annoying, but you got it!
Hi Chris,
1.) Why was the 4136 Op Amp ever designed and sold?
2.) Why does the 4136 Op Amp have it's very own non-standard pin out?
I'm not a fan of most of Bob Carver's auxiliary circuits, and the way he names them. However, his amplifier designs are brilliant. So are his auxiliary circuits if you look at what they are attempting to do. There is a high cost to pay in the form of lots of op amps and ceramic capacitors.
-Chris
Chris, did that Carver have the "Sonic Hologram" stereo expander thing? That was certainly a mixed bag.
Jim - the C4000 had a shitton of features which the stereo sales guys at the time made a game of trying to remember and creatively rename.
Sonic Hologram
Autocorrelator (Noise elimination)
Peak Unlimiter ( dynamic range expansion)
The time delay function we never could quite grasp or demonstrate the effectiveness of/need for.
Remember, this was all done in the analog domain. Lotsa clever circuitry for sure, and controls/switches - definitely not a less is more design.
Sonic Hologram
Autocorrelator (Noise elimination)
Peak Unlimiter ( dynamic range expansion)
The time delay function we never could quite grasp or demonstrate the effectiveness of/need for.
Remember, this was all done in the analog domain. Lotsa clever circuitry for sure, and controls/switches - definitely not a less is more design.
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Hi Chris,
Yes, exactly. The feature names drove me nuts as customers would always ask the tech (me) what it all meant. I guess it was good marketing, but more annoying to me than anything.
More op amps used per square inch than any other piece of home audio gear. Why they chose to use the class B output 4136 with it's stupid pin-out is anybodies guess. It pretty much killed any improvements. I was making my own adapter PCBs, then later we saw the Brown Dog adapters. Beats making my own.
Mine was also attacked by a gorilla who stripped all the case screws. Morons!
-Chris
Yes, exactly. The feature names drove me nuts as customers would always ask the tech (me) what it all meant. I guess it was good marketing, but more annoying to me than anything.
More op amps used per square inch than any other piece of home audio gear. Why they chose to use the class B output 4136 with it's stupid pin-out is anybodies guess. It pretty much killed any improvements. I was making my own adapter PCBs, then later we saw the Brown Dog adapters. Beats making my own.
Mine was also attacked by a gorilla who stripped all the case screws. Morons!
-Chris
