David,
How do you like the LT part with the dual relation ?
How is the noise spec on it? Better than what is in the
HP339A?
How does the LT quad op amp for the buffer for example
and the filter op amp compare to the LME49740?
Did Richard use one of the LTs for the quad opamp?
on the A1 board? Did he use it too for the Filter?
Will have to try and find which he used.
How do you like the LT part with the dual relation ?
How is the noise spec on it? Better than what is in the
HP339A?
How does the LT quad op amp for the buffer for example
and the filter op amp compare to the LME49740?
Did Richard use one of the LTs for the quad opamp?
on the A1 board? Did he use it too for the Filter?
Will have to try and find which he used.
Hey Sync -- one thing to watch with the 339 that no one has mentioned -- misalignment of the switch rotors, and in mine when I got it, a switch rotor 180 degrees out of position -- someone tried "fixing" it. It is hell trying to figure out the switches' correct positions from the schematic, but I strongly recommend that you do this -- I'm thinking that something is really messed up here, and those lousy complicated switches are prime candidates if they've ever been loosened or taken apart. I also had to slightly rotate one switches base/detent assembly and remove the metal index tab that goes into the panel in order to get things lined up correctly. Just another reason that these things are sold with problems....
Boy that brings back memories. A repair/calibration tech at work (LLNL) brought a 339A to me after he had been cleaning those switches... and then couldnt figure out how to reassemble the switch positions. I fixed it for him with the help of the schematic. Wow. That was a LONG time ago.... when the 339A was a new product. Am I really THAT old. Time flys when you are having fun.
-RNM
-RNM
@ Demian,
That is funny thing. I found that to be true for music instrument amplifiers
too. The only reason they are in mint condition now is that because
they didn't sound good, something wrong with them when they were
new, and just put in the closet or garage and forgot about for years.
If they sounded good they were used, played etc. Some with bad speakers.
I found a mint Fender Deluxe Reverb amp from the 1960s that came
from the factory with out solder in the reverb eyelet--critical in a reverb
amp. Since the speaker is in the cabinet even at low volumes it would
sound funny.
Marshall's that were wired up wrong or backwards.
Some with transformer or switches wired backwards, etc.
That is funny thing. I found that to be true for music instrument amplifiers
too. The only reason they are in mint condition now is that because
they didn't sound good, something wrong with them when they were
new, and just put in the closet or garage and forgot about for years.
If they sounded good they were used, played etc. Some with bad speakers.
I found a mint Fender Deluxe Reverb amp from the 1960s that came
from the factory with out solder in the reverb eyelet--critical in a reverb
amp. Since the speaker is in the cabinet even at low volumes it would
sound funny.
Marshall's that were wired up wrong or backwards.
Some with transformer or switches wired backwards, etc.
You'll never be able to upgrade those switches. Those dropped out of sight in the early 80s when analog switches came about. Used to see them in a lot of Japan's stuff from the 70s.
Okay I'm old too.
I did warranty work for both Marshal and Fender among others through the 90s. Everything was wave soldered at the time. The pots and switches sank most of the heat away and were never soldered properly or anything near them. I spent most of my day re-soldering.
Well I did get paid for it. And I wasn't as old then.
Never want to another repair again.
I've got y'all beat. My little girl will be 24 next may.
Oh, that is months. When we go to the store no one
ever asks me if she is mine. Oh, your the grand pa?
No I tell 'em she's mine and she's my first.
OH MY, they say. Yea, I say...
...I am blessed, she is just a great kid.
Now I have to go get her He balloon
off the ceiling. : ) and I couldn't be happier.
Oh, that is months. When we go to the store no one
ever asks me if she is mine. Oh, your the grand pa?
No I tell 'em she's mine and she's my first.
OH MY, they say. Yea, I say...
...I am blessed, she is just a great kid.
Now I have to go get her He balloon
off the ceiling. : ) and I couldn't be happier.
David I image you don't want to do another repair.
I guess you had to repair them with the same cheesy
plastic jack that came with them.
When I could, I'd use a switchcraft and run short leads
to the circuit board. Hopefully I can get back on the
HP over the weekend.
It's really bad here in Tejas, two days ago it was in the
90's and now we have freeze warnings in the a.m. I had
to put on a long sleeve flannel shirt tonight...it's so cold!!!!
Have a good weekend.
I guess you had to repair them with the same cheesy
plastic jack that came with them.
When I could, I'd use a switchcraft and run short leads
to the circuit board. Hopefully I can get back on the
HP over the weekend.
It's really bad here in Tejas, two days ago it was in the
90's and now we have freeze warnings in the a.m. I had
to put on a long sleeve flannel shirt tonight...it's so cold!!!!
Have a good weekend.
Richard,
Good for you. And no, I don't think it ever was "right".
It's had meter oscillation at times and other times it
won't power on.
Then if something happens, it goes into non working mode
and I have to leave alone.
When I come back to it, it will work. It's had a funky
intermittent, that I haven't figured out.
Clearly I've got that noise problem from the function selector,
and that 5kHz bandwidth hump noise.
This is with the RCAs unplugged so no signals.
and a 600s in the Distortion Analyzer inputs.
Good for you. And no, I don't think it ever was "right".
It's had meter oscillation at times and other times it
won't power on.
Then if something happens, it goes into non working mode
and I have to leave alone.
When I come back to it, it will work. It's had a funky
intermittent, that I haven't figured out.
Clearly I've got that noise problem from the function selector,
and that 5kHz bandwidth hump noise.
This is with the RCAs unplugged so no signals.
and a 600s in the Distortion Analyzer inputs.
My 3 are 25, 31, and 34. By the time the youngest arrived, my wife had to explain to me how gray-haired ladies got pregnant. It has something to do with gray-haired men as I recall.
I enjoyed taking our babies to the store. I discovered that the most sure-fire way to meet attractive, eligible girls is to walk into a shopping center or department store while carrying a baby. I wish I had discovered this about a decade earlier; I'd advise any guy who can't seem to find a girlfriend to borrow somebody's baby and go shopping.
Dale
That's funny Dale.
I was all worried about having a baby at my age (well my wife did
all the work for it, I just had the fun), my car guy told me to not
worry about it your genes kick in and you know how to care for
them. Yep pointers help too.
They do kick in. No way I'm letting my baby be taking to the
store or mall by any of my single friends. Heck I don't even
like folks being overly nice to her unless I know and trust them.
AND
Now that I think about it, yeah I've met some very attractive ladies too.
Demian, Tejas is big, I keep forgetting that. North Texas around
Dallas Fort Worth Denton, nicknamed the Metroplex.
I was all worried about having a baby at my age (well my wife did
all the work for it, I just had the fun), my car guy told me to not
worry about it your genes kick in and you know how to care for
them. Yep pointers help too.
They do kick in. No way I'm letting my baby be taking to the
store or mall by any of my single friends. Heck I don't even
like folks being overly nice to her unless I know and trust them.
AND
Now that I think about it, yeah I've met some very attractive ladies too.
Demian, Tejas is big, I keep forgetting that. North Texas around
Dallas Fort Worth Denton, nicknamed the Metroplex.
The Beat Goes on
Here is the main Oscillator Amplifier, op Amp A1u1 LT1468.
after all the other changes. Still apart, no signal etc.
Set up at -4v bias.
This is the plot right at pin 6.
That is with the change to the 1000 pf feedback cap added.
And changes to the power supply.
I guess I start adding capacitors back in the compensation loops?
Here is the main Oscillator Amplifier, op Amp A1u1 LT1468.
after all the other changes. Still apart, no signal etc.
Set up at -4v bias.
This is the plot right at pin 6.
That is with the change to the 1000 pf feedback cap added.
And changes to the power supply.
I guess I start adding capacitors back in the compensation loops?
No way -- those caps won't work with the 1468 anyway. If your FET bias is -4V, then it's 10X too high. Tweak the bias (gain) pot while watching the distortion products on the QA -- you'll see when things are optimum. Do this at 1kHz. The picket fence of distortion products you're showing there indicate that the system is about to go into clipping....