2254C build/support thread

[muffy1975]

Team,

can CHF1 and CHF2 be polyester caps? Or do they need to polystyrene caps? Can I use metalised paper caps here?

Michael

 

[Igor]

Polyester/metalised paper caps fine here as well (they setting the sidechain HPF freq. with SC HPF switch) and has no effect to audio quality.

 

[jandoste]

hello All,
I have almost finished the n2254 but  two/three bug is discoverable for me.
1 -Gain is not function properly: I have no signal change with 1 +2 +3 +4 +5 + switch and when I switch to 6th I have a level too high!!!
I tried what Igor says ;
"before clipping.
Check the reistors on gain switch; if all is fine according to schematic:
feed +10 db signal to input, crank the makeup switch till output starts to clip,
no compression (put comp threshold to +10); take a scope and check the output of
2254C
with 1k load in parallel, it should have about +26..28 DBU max undistorted
signal at its output.
Adjust second half of BA283 (output section) for minimum distortion @+27dbU,
by turning 5k trimpot located near the 2N3055.
For more info about quiescent current for Neve class A check the web."

2 nd: threshold!
when I turned to -12 dB I think it does not work! I have no compression with the threshold when I switch to -20 it works !

Maybe I got some problem with cables (grounds)?
Any idea ?
Thanks

OK... it looks like wrong resistor.
Disconnect the cable going from makeup switch to main pcb, and measure
the resistance at every step. Compare with schematic.

Do same for threshold switch.

Regarding the threshold, what is the input level?

BTW, to be clear, you told about low clipping point as well and posted my answer related to this,
please don't mix different things

Hi Igor,
it was not the resistors ! I checked all resistors and all resistors are right !
so, what I do guys ?


PS : listen this great sound ! Nice work mr Igor !
dry; https://files.me.com/umitceyhan/6uy0fs.wav
wet; https://files.me.com/umitceyhan/ehj16a.wav

 

[user 10827]

Sounds to me you may have the wrong Loring switches in there? you sure you dont have a 2x6 rather than a 1x12?

 

[jandoste]

Sounds to me you may have the wrong Loring switches in there? you sure you dont have a 2x6 rather than a 1x12?

Hi Pete,
Thanks for the reply !
I checked it too ! it's right Loring too
cheers,

 

[Rybow]

You could change out the lorlin. It may have become damaged during soldering or may be defective or something. I have had that problem before with these switches. If they get too hot, they get screwed up!

 

[Igor]

The PCB's are 2OZ, and I replaced the components on these PCB's when prototyping many times....
Desoldering iron pump-gun like Hakko808 can be useful.
If you don't have desoldering gun, desoldering tape with 2 layers PCB is useless in case of Lorlin switch.

If you're not familar with 2 layer PCB de-soldering, there is a simple strategy.

Don't affraid to brake old component, save the PCB.

I.e. open the Lorlin switch; heat the pins from the PCB side and pull them out one-by-one
through the switch body, using tweeser or whatever. A pathological switch autopsy.
Music with growling vocals at background can help a lot when desoldering.

GOOD IRON IS MUST HERE, LIKE WSD80 etc, don't use "needle" head, 2....3mm tip is good choice,
at 370 deg temp., if you used 40/60 alloy. Don't affraid to use bit more of alloy and flux.
You always can clean the residue.

Than, just soak solder leftovers with desoldering tape or pump, clean with isoprop alcoghole
and solder the right switch. When cleaning, good to use toilet paper to wipe the board
Hm...Do you call this in English kinda "toilet humor" ?

 

[Winetree]

I have some N.O.S. Motorola 3055's made in the USA.  Should I use these instead of the ST 2n3055's?
Is there a sound difference?

 

[Igor]

I have some N.O.S. Motorola 3055's made in the USA.  Should I use these instead of the ST 2n3055's?
Is there a sound difference?

This question should be posted out of this thread.
Of course, the sound will be more punchy, beefy, cruncny and all possible BS.

Here is the build/support thread.

 

[jandoste]

The PCB's are 2OZ, and I replaced the components on these PCB's when prototyping many times....
Desoldering iron pump-gun like Hakko808 can be useful.
If you don't have desoldering gun, desoldering tape with 2 layers PCB is useless in case of Lorlin switch.

If you're not familar with 2 layer PCB de-soldering, there is a simple strategy.

Don't affraid to brake old component, save the PCB.

I.e. open the Lorlin switch; heat the pins from the PCB side and pull them out one-by-one
through the switch body, using tweeser or whatever. A pathological switch autopsy.
Music with growling vocals at background can help a lot when desoldering.

GOOD IRON IS MUST HERE, LIKE WSD80 etc, don't use "needle" head, 2....3mm tip is good choice,
at 370 deg temp., if you used 40/60 alloy. Don't affraid to use bit more of alloy and flux.
You always can clean the residue.

Than, just soak solder leftovers with desoldering tape or pump, clean with isoprop alcoghole
and solder the right switch. When cleaning, good to use toilet paper to wipe the board
Hm...Do you call this in English kinda "toilet humor" ?

Hi Igor,
Thanks for the reply sir
I have already changed the "gain lorlin switch"and  got same problem so I would like to get some nice switches from Colin -->http://www.audiomaintenance.com/acatalog/LO-03-001_extended_info.html

Did you try them ?
Thanks !

 

[jandoste]

Bump!

 

[Igor]

I have already changed the "gain lorlin switch"and  got same problem

Please clarify what is the problem, let's try to fix it together.
IIRC, the Lorlin switches were 2x6 instead of 1x12, right? So, you replaced them AND?....
Please more info!

Regarding the switches from Audiomaintenance: check they have round, not "shaved" at one side shaft.
In general, should work fine.

 

[jandoste]

I have already changed the "gain lorlin switch"and  got same problem

Please clarify what is the problem, let's try to fix it together.
IIRC, the Lorlin switches were 2x6 instead of 1x12, right? So, you replaced them AND?....
Please more info!

Regarding the switches from Audiomaintenance: check they have round, not "shaved" at one side shaft.
In general, should work fine.

Hi Igor,
I changed them but I'm not sure that the lorlins was right or they had some buggy ! I want to finih this project because I loved what I heard like the sound that they got ! and what you build ! Great job !

What do you think about this error Igor? R47 may wrong V ? or wires connection problem ? or PSU problem?
If you have an idea for helping me I will try to find the problem ! but I'm not hardware engineer so I am searching the problem slowly and everywhere )))))
Cheers,

 

[muffy1975]

Hi team,

more cap questions.

Can I use 0.1uf 63v polyester box caps in place of the 0.1uf ceramic caps that are needed around the circuit or will this effect the quality of the unit?

Can the 47uf tantalum on the control panel be replaced with an electrolytic cap of the same value? What does this particular cap do?

Many thanks in advance 

Michael
Oxford
England

ps my 2nd 2254c PCB has arrived. Joy of Joy. Will complete the 2nd ( part of a stereo ) unit early next year. One at a time. ;D

 

[Rybow]

Heya! Slowly making progress on this thing. Had to take a DIY break for a bit, but now, its on!

Anyways, I was in an electronics store a couple of days ago looking for some BC214's for this build, and they suggested a 2n2907 as a replacement. Anyone know if it will work?


Ryan

 

[Igor]

Frank (Electrochronic) supposed to have BC214's, if this is still relevant....

Can I use 0.1uf 63v polyester box caps in place of the 0.1uf ceramic caps that are needed around the circuit or will this effect the quality of the unit?

Why not... Polyesters will work fine. Anyway, ceramic X7R IMHO are the best choice for power supply bypassing.

Can the 47uf tantalum on the control panel be replaced with an electrolytic cap of the same value? What does this particular cap do?

Used for A1/A2 time constants. Low leakage low ESR electrolytic cap should work as well.

Hi Igor,
I changed them but I'm not sure that the lorlins was right or they had some buggy ! I want to finih this project because I loved what I heard like the sound that they got ! and what you build ! Great job !

Something is wrong with resistors.
Let's do next. Take 2 wires and 2 crocodile clips.
Disconnect MKUP connector from control PCB .
Solder wires to MKUP (Molex 2 pin connector) at the PCB side on control PCB.
Connect wires with crocodiles to multimeter, OHM, 20k range.
Pass on every step and write this down to paper...see the schematic....probably you will
find out wrong resistor, bad contact or broken trace.

Same for com_threshold switch, solder wires on pins 1-2 of THR' connector.

 

[jandoste]

Hi Igor,
I changed them but I'm not sure that the lorlins was right or they had some buggy ! I want to finih this project because I loved what I heard like the sound that they got ! and what you build ! Great job !

Something is wrong with resistors.
Let's do next. Take 2 wires and 2 crocodile clips.
Disconnect MKUP connector from control PCB .
Solder wires to MKUP (Molex 2 pin connector) at the PCB side on control PCB.
Connect wires with crocodiles to multimeter, OHM, 20k range.
Pass on every step and write this down to paper...see the schematic....probably you will
find out wrong resistor, bad contact or broken trace.

Same for com_threshold switch, solder wires on pins 1-2 of THR' connector.

Hi Igor,
I did it ,
1-1M
2-78k
3-76k5
4-75k8
5-75k5
6-75k4
7-75k2
8-209k
9-160r
10-127r
11-125r
Strange ! when I measure the resistor out of main board PCB(with out any connection) they have right value ! but when I measure with this way
"Let's do next. Take 2 wires and 2 crocodile clips.
Disconnect MKUP connector from control PCB .
Solder wires to MKUP (Molex 2 pin connector) at the PCB side on control PCB." they are wrong?
what do you think ? I have to change all resistors( Mkup side) or may I got a big problem
Thanks,

 

[Igor]

when I measure the resistor out of main board PCB(with out any connection) they have right value !

Something is wrong with Ohm's law than...

1-1M
2-78k
3-76k5
4-75k8
5-75k5
6-75k4
7-75k2
8-209k<---!!!!<---strange!!!
9-160r
10-127r
11-125r

First, you mean com_mkup switch, right? (by values, it should be).
OK than... Actually it should measure from CCW (11th pos) to CW (1st pos)
something like: 100R-127R-160R-211R-286R-396R-.....-3306r-1MEG

Check all the traces, BUT I think there's some K values used instead of Ohms...

Logic is absolutely missing here, BTW. I suppose, somehow 8th pos is 209R,
this way, just replace 75K resistor to 75 OHM...should work;
something strange with 10th and 11th pos, should be
10th 127R
11th 100R
but this is less important for now.
Please check resistor supposed to be 75 OHM....and, maybe, replace, depending on result

 

[jandoste]

First, you mean com_mkup switch, right? (by values, it should be).
OK than... Actually it should measure from CCW (11th pos) to CW (1st pos)
something like: 100R-127R-160R-211R-286R-396R-.....-3306r-1MEG

Check all the traces, BUT I think there's some K values used instead of Ohms...

Logic is absolutely missing here, BTW. I suppose, somehow 8th pos is 209R,
this way, just replace 75K resistor to 75 OHM...should work;
something strange with 10th and 11th pos, should be
10th 127R
11th 100R
but this is less important for now.
Please check resistor supposed to be 75 OHM....and, maybe, replace, depending on result

B-I-N-G-O

B-I-N-G-O

B-I-N-G-O
Yes, It was 75K how I didn't see it !!!! sh***tttttt/f***ck ! so I soldered 75R and it works ! yalla
Thanks Igor! you are the SIR  !
Best regards !

 

[Igor]

MMMM...Thank YOU for patience and carefully checking the resistors
As you see, I did nothing. Now, to com_threshold switch?