Hi, i've got a problem or several...don't know. My first DIY project sounds more in the chassis than in the speaker. The output is so low i've got to stuck my ear in the speaker to hear anything.... but it also sounds in the chassis-output transformer- a Hammond 125ESE.
What's wrong?
I've no idea...seems the OT connections.....output transformer- a Hammond 125ESE.
Is a very simple design with only one channel and one PCL86.
Filaments and b+ voltage are ok. No smoke either. Can someone help? I can post pics and schematics.
I'm a newbie
What's wrong?
I've no idea...seems the OT connections.....output transformer- a Hammond 125ESE.
Is a very simple design with only one channel and one PCL86.
Filaments and b+ voltage are ok. No smoke either. Can someone help? I can post pics and schematics.
I'm a newbie
o/p Tx
If you can hear the sound coming from the O/P Tx, even though its pretty quiet, it sounds to me like the O/P stages are driving the Tx, but for some reason it aint getting to the speaker.
Check you have continuity at the secondary of the Tx, and check the wiring to the speaker sockets or whatever is in series with the speaker--Its also possible you may have a short at the secondary maybe where the wires come out of the transformer covering etc
Its also possible that the Tx has shorted turns(hopefully not!)
Check also, any parallell caps on either the secondary or primary of the Tx
Its possible also, for the PCL86 to give some odd faults, They used to be used in the audio stages of TV sets, and sometimes would give a small pop through the speaker, then almost inaudible, quiet sound for a mimiute or so, then pop back on!
Not sure what went wrong with the valve, but a replacement effected a complete cure
If you can hear the sound coming from the O/P Tx, even though its pretty quiet, it sounds to me like the O/P stages are driving the Tx, but for some reason it aint getting to the speaker.
Check you have continuity at the secondary of the Tx, and check the wiring to the speaker sockets or whatever is in series with the speaker--Its also possible you may have a short at the secondary maybe where the wires come out of the transformer covering etc
Its also possible that the Tx has shorted turns(hopefully not!)
Check also, any parallell caps on either the secondary or primary of the Tx
Its possible also, for the PCL86 to give some odd faults, They used to be used in the audio stages of TV sets, and sometimes would give a small pop through the speaker, then almost inaudible, quiet sound for a mimiute or so, then pop back on!
Not sure what went wrong with the valve, but a replacement effected a complete cure
Hi, thanks for the replies. My situation is worst than yesterday. I have soldered all over again and now i've got volume, oh yes, plenty of it.😱 As the valve starts to warm up (5s) i don't hear anything but soon a horrible hum starts and goes louder and louder; i had to shut it off all scared i might blow a speaker. So i don't know the end.
Voltages: the guy who did the design said 285v for the anode. It reads 280v, the transformer gives me 220 and after the rectifying and the caps goes like this,318, 319, 306 and 280 in the anode. The blue transformer's primary(pin six) reads 316v. The brown goes to B+ and it reads 319v. Here's the schematic:
http://www.tnt-audio.com/clinica/ta/pcl86.html
I didi post the pics but maybe(my first time) doesn't work.
Filaments are Ok.
I am in a dead end so i'll appreciate any help.
Thanks
Voltages: the guy who did the design said 285v for the anode. It reads 280v, the transformer gives me 220 and after the rectifying and the caps goes like this,318, 319, 306 and 280 in the anode. The blue transformer's primary(pin six) reads 316v. The brown goes to B+ and it reads 319v. Here's the schematic:
http://www.tnt-audio.com/clinica/ta/pcl86.html
I didi post the pics but maybe(my first time) doesn't work.
Filaments are Ok.
I am in a dead end so i'll appreciate any help.
Thanks
Remove C1 and listen for hum. You my be able to determine which stage is the problem.
Also, check that the heater pins do not connect to any signal pin.
I don't know much Italian, but the author seems to have a sense of humour 😉
Also, check that the heater pins do not connect to any signal pin.
I don't know much Italian, but the author seems to have a sense of humour 😉
Thanks!!!!! It did work. Without the C1 the hum is gone and the music is here....still output too low....maybe used valves...maybe 2w only but i have a 99dB speaker and it should .....wait it is increasing the power now....slow amp....
Thanks, how did you find out it was the c1? I want to learn. Very happy with the help.
The output seems still low...i'll buy new tubes and post the results
Cheers
Alk
Thanks, how did you find out it was the c1? I want to learn. Very happy with the help.
The output seems still low...i'll buy new tubes and post the results
Cheers
Alk
Hi,
Ahum....It isn't C1 that's at fault here I think.
Seems to me you're listening to the feedback loop or something similar.
Not sure what but something must be hooked up all wrong.
John,
You should patent that Loftin White of yours...😀
Cheers,😉
Ahum....It isn't C1 that's at fault here I think.
Seems to me you're listening to the feedback loop or something similar.
Not sure what but something must be hooked up all wrong.
John,
You should patent that Loftin White of yours...😀
Cheers,😉
Well...as i said i'm learning electronics just because i love tubes...and...i do make mistakes.
Now the voltage readings with the valve on are quite different...or was it the c1 which is gone now?
Anyway these are the values with music playing:
Pin9 114v!!!!
Pin 6 267v
B+ 270v
I've removed the negative feedback....sound still low....but not in the chassis anymore...that was fixed...a banana wasn't properly installed.
No clue where is the mistake....i have rechecked everything ...is the design right?
The sound is good but the output power isn't enough. My room is small and i thought 2W per channel was ok...so i was told.
Well still struggling with the first channel..... I reckon the output is only about 0.25 or 0.50 watts. My pc fan sounds louder.
Thanks for the replies
Now the voltage readings with the valve on are quite different...or was it the c1 which is gone now?
Anyway these are the values with music playing:
Pin9 114v!!!!
Pin 6 267v
B+ 270v
I've removed the negative feedback....sound still low....but not in the chassis anymore...that was fixed...a banana wasn't properly installed.
No clue where is the mistake....i have rechecked everything ...is the design right?
The sound is good but the output power isn't enough. My room is small and i thought 2W per channel was ok...so i was told.
Well still struggling with the first channel..... I reckon the output is only about 0.25 or 0.50 watts. My pc fan sounds louder.
Thanks for the replies
Hi,
Audio electronics is SO much fun. I replaced the c1 cap on frank's suggestion and 🙂 🙂 🙂 now i've got the real thing.
Don't understand a thing, it is orange drop so that discards a wrong polarity....well here's the music and 2W is TOO loud.
Ok not all well. First too loud and distorted. The designer wrote input sensivity was ok without need of a preamp....and that you should adjust the volume from your cd player. My problem is that i can't....it plays at the same volume (maximum) with the lowest setting in the cd player. Guess i'll have to do a preamp circuit. Is the distortion normal at the higher gain?
- 230v makes you feel funny for a few seconds.......just up to my shoulder.
Cheers
Audio electronics is SO much fun. I replaced the c1 cap on frank's suggestion and 🙂 🙂 🙂 now i've got the real thing.
Don't understand a thing, it is orange drop so that discards a wrong polarity....well here's the music and 2W is TOO loud.
Ok not all well. First too loud and distorted. The designer wrote input sensivity was ok without need of a preamp....and that you should adjust the volume from your cd player. My problem is that i can't....it plays at the same volume (maximum) with the lowest setting in the cd player. Guess i'll have to do a preamp circuit. Is the distortion normal at the higher gain?
- 230v makes you feel funny for a few seconds.......just up to my shoulder.
Cheers
Hi again,
just to say all my problems are resolved...this amp sounds GREAT....now i'm hooked to valves and my first project won't be the last.
¡Viva Triode!
Thanks for the help......the OT primary had a cold connection to B+ and one of my valves has a very irregular behaviour confusing me more.
Nice moderators
Cheers😀
just to say all my problems are resolved...this amp sounds GREAT....now i'm hooked to valves and my first project won't be the last.
¡Viva Triode!
Thanks for the help......the OT primary had a cold connection to B+ and one of my valves has a very irregular behaviour confusing me more.
Nice moderators
Cheers😀
- Status
- Not open for further replies.