Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Aug Thu 06, 2020 1:41 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 923 posts ]  Go to page Previous  1 ... 17, 18, 19, 20, 21, 22, 23 ... 47  Next
Author Message
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 2:48 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
BTW:
On my 6V6 amp's power supply I just changed the AC incoming 5 ohm surge-resistor to a thermister SL-15 22102 (also CL-90 similar)
It seems like a better long term choice.
I was having problems with the 5 ohm 5 watt opening up after a while... then I recently increased it to 10 watts.
But tonight I thought that a CL-90 or an SL-15 22102 would be a better choice.
It starts out at 220 ohms then drops to a couple ohms when hot.

The CL-90 starts out at 120 ohms the drops to a couple ohms hot.

The SL-15 22102 can handle up to 2 amps and the Cl-90 can also handle up to 2 amps.
Either will work.

SL-15 22102:
https://www.mouser.com/ds/2/600/SL1522102-276444.pdf

CL-90:
https://www.mouser.com/productdetail/?q ... faLQ%3D%3D

Image

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Feb Sun 04, 2018 3:59 am, edited 5 times in total.

Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 2:57 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
I've also pulled out the OPA 604 op-amps...
I've been listening with those in place the past cpl days... and although I can't say there was anything I actually heard wrong... but it just seemed so un-impressive and "ordinary"
My music list of Jazz tunes normally has very enjoyable "round" and "full" ... impressive sounding tones.
But with opa-604 it all just seemed flat and ordinary.

So tonight I put the op-275s back in... and I was immediately reminded of why I love this music once again...
An undefinable but impressive difference.
Happy :-)

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:04 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
Good idea Flip. I will pull opamps and check further. I double checked the wiring very close, seems ok. Also, the NFB circuits are correct to the schematic, but have a problem. I will check on the gridleak to ground circuits. Wired yes, solder joint problem, knowin myself, I don't know.
The 'squeal' sounds like NFB is off the wrong side of the OPT secondary. Of course, it could also be a myriad of things if the opamps aren't wired/working right and you apparently have a problem there too. That's why I suggested wiring the amp up in stages, starting with the output tubes. That reduces the odds of problems compounding on you. For example, once the output tubes are settled then if they over current, or something else, when the opamp drivers are installed you know it's them and not the output tubes. But by, hail Mary, throwing all together it's a lot more difficult to know where the problem(s) is(are).

The 'hot' resistor on the tone amp supply might also be caused by the 3.3 uF cap being +50% on the tolerance side. Check the cap's actual value. Of course, it also might be a wiring problem with the tone chip causing it to pull excessive current but if that were the case I wouldn't expect to see the correct voltage on it because the supply simple can't provide more current than about 60 mA, even with a dead short across it, **IF** the cap is the right value. If the cap is on the high tolerance side of 3.3 uF, that being almost 5 uF, the dissipation of the 470 Ohm resistor shoots up to almost 4 Watt, which would get a 5 Watt resistor pretty warm, especially in a tight space.




I built it so I could isolate the sections. That worked well to troubleshoot.
Will check on the cap value. It says 3.3 on the body.
Went to check the current draw for the tone amp. There wasn't any. I forgot to connect the ground pin (18) to ground. So the hot resistor is not because of an overload. After connecting to ground, I read 39ma.
So, I hooked everything back up, through the tone section. Turned on and now had full, uncontrollable volume. Found that the volume pot is defective. Connected a replacement pot. Now the amp is working, with full tone controls.
B+ is down to 290 and R1-R2 are very hot.
I also noticed that the opa604's are warm, not hot.
And some static in one channel. Least of the worries right now.

Flip, to change the OPT output relation to the primary, could I just swap the V1/V2 connections from the preamp?
I always get confused here.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:15 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Pbpix wrote:
I've also pulled out the OPA 604 op-amps...
I've been listening with those in place the past cpl days... and although I can't say there was anything I actually heard wrong... but it just seemed so un-impressive and "ordinary"
My music list of Jazz tunes normally has very enjoyable "round" and "full" ... impressive sounding tones.
But with opa-604 it all just seemed flat and ordinary.

So tonight I put the op-275s back in... and I was immediately reminded of why I love this music once again...
An undefinable but impressive difference.
Happy :-)




Happy
That's the way I like it Peter.
Planning a new amp, ordering parts, building an awesome sounding box. You guys designing it.
That makes me Happy.
And I am Happy.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:35 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 9664
Location: Texas. USA
john8750 wrote:
Flipperhome wrote:
The 'squeal' sounds like NFB is off the wrong side of the OPT secondary. Of course, it could also be a myriad of things if the opamps aren't wired/working right and you apparently have a problem there too. That's why I suggested wiring the amp up in stages, starting with the output tubes. That reduces the odds of problems compounding on you. For example, once the output tubes are settled then if they over current, or something else, when the opamp drivers are installed you know it's them and not the output tubes. But by, hail Mary, throwing all together it's a lot more difficult to know where the problem(s) is(are).

The 'hot' resistor on the tone amp supply might also be caused by the 3.3 uF cap being +50% on the tolerance side. Check the cap's actual value. Of course, it also might be a wiring problem with the tone chip causing it to pull excessive current but if that were the case I wouldn't expect to see the correct voltage on it because the supply simple can't provide more current than about 60 mA, even with a dead short across it, **IF** the cap is the right value. If the cap is on the high tolerance side of 3.3 uF, that being almost 5 uF, the dissipation of the 470 Ohm resistor shoots up to almost 4 Watt, which would get a 5 Watt resistor pretty warm, especially in a tight space.
I built it so I could isolate the sections. That worked well to troubleshoot.
Will check on the cap value. It says 3.3 on the body.
Went to check the current draw for the tone amp. There wasn't any. I forgot to connect the ground pin (18) to ground. So the hot resistor is not because of an overload. After connecting to ground, I read 39ma.
So, I hooked everything back up, through the tone section. Turned on and now had full, uncontrollable volume. Found that the volume pot is defective. Connected a replacement pot. Now the amp is working, with full tone controls.
B+ is down to 290 and R1-R2 are very hot.
I also noticed that the opa604's are warm, not hot.
And some static in one channel. Least of the worries right now.

Flip, to change the OPT output relation to the primary, could I just swap the V1/V2 connections from the preamp?
I always get confused here.
Yes, you could swap the V1/V2 connections for the same effect.

Of course the cap says 3.3 uF on the body but they have a tolerance, usually -20% +50%. So it can be 4.95 uF and be perfectly 'in spec'.

Sounds like something might be still pulling too much power if R1/R2 are excessively hot (they will be quite warm at the higher idle current as they were originally size for the lower idle). What value and Wattage did you use?


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:36 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
john8750 wrote:

. There wasn't any. I forgot to connect the ground pin (18) to ground. So the hot resistor is not because of an overload. After connecting to ground, I read 39ma.
.

Something is wrong.
If the board was not drawing any load... that means the only load was the 470 resistor and the 13v Zener .

So if there is about 33v feeding the 470 resistor ... and the Zener is the only other load... it still drops 20v across the 470 resistor @ a max of 42ma
20v / 470 ohm = 42ma

But even is the Zener wasn't working and you had a dead short... then the whole 33v would drop across the 470 resistor drawing only a max of 70ma
33v / 470 ohm = 70ma

So something doesn't add up making the 5 watt 470 resistor get so hot.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:37 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
How many volts do you read feeding into the 470 resistor?

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:42 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
john8750 wrote:
B+ is down to 290 and R1-R2 are very hot.
I also noticed that the opa604's are warm, not hot.
And some static in one channel. Least of the worries right now.

Flip, to change the OPT output relation to the primary, could I just swap the V1/V2 connections from the preamp?
I always get confused here.

Which R1 / R2 do you mean?

The resistors in the +/- 24v supply for the opa604s?

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 4:45 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
Flipperhome wrote:
Yes, you could swap the V1/V2 connections for the same effect.

John... if you swap the plate leads .....remember to swap the UL taps too.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 5:07 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
Flipperhome wrote:
The 'squeal' sounds like NFB is off the wrong side of the OPT secondary. Of course, it could also be a myriad of things if the opamps aren't wired/working right and you apparently have a problem there too. That's why I suggested wiring the amp up in stages, starting with the output tubes. That reduces the odds of problems compounding on you. For example, once the output tubes are settled then if they over current, or something else, when the opamp drivers are installed you know it's them and not the output tubes. But by, hail Mary, throwing all together it's a lot more difficult to know where the problem(s) is(are).

The 'hot' resistor on the tone amp supply might also be caused by the 3.3 uF cap being +50% on the tolerance side. Check the cap's actual value. Of course, it also might be a wiring problem with the tone chip causing it to pull excessive current but if that were the case I wouldn't expect to see the correct voltage on it because the supply simple can't provide more current than about 60 mA, even with a dead short across it, **IF** the cap is the right value. If the cap is on the high tolerance side of 3.3 uF, that being almost 5 uF, the dissipation of the 470 Ohm resistor shoots up to almost 4 Watt, which would get a 5 Watt resistor pretty warm, especially in a tight space.
I built it so I could isolate the sections. That worked well to troubleshoot.
Will check on the cap value. It says 3.3 on the body.
Went to check the current draw for the tone amp. There wasn't any. I forgot to connect the ground pin (18) to ground. So the hot resistor is not because of an overload. After connecting to ground, I read 39ma.
So, I hooked everything back up, through the tone section. Turned on and now had full, uncontrollable volume. Found that the volume pot is defective. Connected a replacement pot. Now the amp is working, with full tone controls.
B+ is down to 290 and R1-R2 are very hot.
I also noticed that the opa604's are warm, not hot.
And some static in one channel. Least of the worries right now.

Flip, to change the OPT output relation to the primary, could I just swap the V1/V2 connections from the preamp?
I always get confused here.
Yes, you could swap the V1/V2 connections for the same effect.

Of course the cap says 3.3 uF on the body but they have a tolerance, usually -20% +50%. So it can be 4.95 uF and be perfectly 'in spec'.

Sounds like something might be still pulling too much power if R1/R2 are excessively hot (they will be quite warm at the higher idle current as they were originally size for the lower idle). What value and Wattage did you use?




I will reverse the grid connections.

If the 3.3 is not correct, then the other one will be the same.
Will be a job to replace them, but will pull em for a check.
All the resistors in the IC power supply are running a bit on the hot side.
Should I look for a reading of less capacitance to be the problem?
BTW- voltage going into the 470ohm resistor is 43volts.
I forgot about this Flip. I added a 470K drain resistor across the 3.3uf cap.
Also noticed you have a 22ohm ballast resistor on the other supply. Could this help here?

R1/R2 in the power supply are 47ohm 2watt.
I wonder about the low B+, 290volts.
May be better if I went back to 25ma on the cathodes?

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 5:12 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Pbpix wrote:
How many volts do you read feeding into the 470 resistor?



43volts feeding the 470ohm resistor. Zener is 13volt 5watt (1N5350B). Wired correctly to the schematic getting very hot with 0ma load. :?

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 5:13 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Pbpix wrote:
john8750 wrote:
B+ is down to 290 and R1-R2 are very hot.
I also noticed that the opa604's are warm, not hot.
And some static in one channel. Least of the worries right now.

Flip, to change the OPT output relation to the primary, could I just swap the V1/V2 connections from the preamp?
I always get confused here.

Which R1 / R2 do you mean?

The resistors in the +/- 24v supply for the opa604s?



The resistors in the B+ supply.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 5:15 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Pbpix wrote:
Flipperhome wrote:
Yes, you could swap the V1/V2 connections for the same effect.

John... if you swap the plate leads .....remember to swap the UL taps too.




Imagonna interchange the grids in each channel. Easiest way to do it.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 5:26 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Here are the caps I used. What voltage should be dropped across them?
https://www.ebay.com/itm/2pcs-3-3uF-250 ... 1438.l2649

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 5:57 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
john8750 wrote:
Pbpix wrote:
How many volts do you read feeding into the 470 resistor?



43volts feeding the 470ohm resistor. Zener is 13volt 5watt (1N5350B). Wired correctly to the schematic getting very hot with 0ma load. :?

43v is a lot.
and if you have no load you'll be pulling 63ma through the 470 resistor into the Zener.
About 2 watts
And a short will draw 91ma through the 470 ohm
which is 4 watts right there.

BTW... are you using Flip's full wave doubler supply?

Please re-post the entire current schematic... ok?

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Feb Sun 04, 2018 6:18 am, edited 2 times in total.

Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 6:07 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
I'm using only 2uf for the supply that can use eithe 24v Zeners or 20v Zeners.
It works without anything hot for the 24v opa604a at 22.5ma
Each opa604 draws approx 5.7ma

Image

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 6:32 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22622
Location: Haledon, NJ, usa
Is this the latest print?
If so... you can see it say 100ma for the 6v6s... but you are using 152ma now.
47 ohms x 152ma = 7.2volts
7.2v x .152A = 1 watt ( triple for safety) 3 to 5 watts
So R1 and R2 should be larger than 2watts


Image

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Feb Sun 04, 2018 6:39 am, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 6:36 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 9664
Location: Texas. USA
john8750 wrote:
Here are the caps I used. What voltage should be dropped across them?
https://www.ebay.com/itm/2pcs-3-3uF-250 ... 1438.l2649
Ah, okay. That +50% I mentioned is for electrolytics. Those caps have a tighter tolerance. although I don't know what it is because in the title it say 5% and then lower it says 10%. At any rate, it's shouldn't be 50%.

The voltage on the filter cap sims out as 40 VDC so the 43 VDC your seeing (on the tone control supply) is within reason (AC a bit higher, cap tolerance, etc.). At 43 VDC (the voltage you're seeing) - 12 VDC (the zener) power across the 470 Ohm is 2 Watt and it's spec'd as a 5 Watt.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 8:52 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Here is my power supply schematic, as built.
Attachment:
finalps.png
finalps.png [ 149.13 KiB | Viewed 896 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Sun 04, 2018 10:42 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 5328
Location: Los Angeles
Here is the power supply showing the power needed for the cap dropper IC section. 313ma.
Not very practical. The output load demand is only 65ma. That's for the tone amp, and preamp only.
Attachment:
maa.png
maa.png [ 149.81 KiB | Viewed 893 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
Post New Topic Post Reply  [ 923 posts ]  Go to page Previous  1 ... 17, 18, 19, 20, 21, 22, 23 ... 47  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: Als_Basement and 11 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB