Spencerleehorton
Well-known member
I did explain how to do this at the start of the thread.
I just searched for the 2254 Pcbs in google.
I just searched for the 2254 Pcbs in google.
Neve 2254 build with ba185, ba191, ba192, ba283
- Thread starter Spencerleehorton
- Start date
Help Support GroupDIY Audio Forum:
Spencerleehorton
Well-known member
Spencerleehorton said:
Looking good. I like those cpc cases. I use so many of them I can remember the stock number EN55272. haha
Last edited:
Spencerleehorton
Well-known member
Thought I’d do a little update,
Both channels compressing but hum on channel 2 and intermittent ratio switch pot?
Still a way off from setting up properly!!!
Will try and run each channel off it’s own Psu and see if it improves hum and check gnd.
Both channels compressing but hum on channel 2 and intermittent ratio switch pot?
Still a way off from setting up properly!!!
Will try and run each channel off it’s own Psu and see if it improves hum and check gnd.
Attachments
Spencerleehorton
Well-known member
My main aim whilst all this chaos is going on is to try and get this stereo unit working perfectly and shed some more light on how this circuit works.
Also having a specific schematic to work from and some working voltages on all transistors. (I have a working channel but it still needs some work, have recorded voltages)
I have attached a schematic which i have doctored and would like if possible for it to be checked and verified that its correct.
Once this is then sorted i will alter the circuit and then go through all pcbs and record all components, values and voltages and have a spreadsheet with them all on.
If this would then help everyone else whos having problems I will of cause share all my findings.
Please look at schematic and verify that what i have removed is correct please.
Also having a specific schematic to work from and some working voltages on all transistors. (I have a working channel but it still needs some work, have recorded voltages)
I have attached a schematic which i have doctored and would like if possible for it to be checked and verified that its correct.
Once this is then sorted i will alter the circuit and then go through all pcbs and record all components, values and voltages and have a spreadsheet with them all on.
If this would then help everyone else whos having problems I will of cause share all my findings.
Please look at schematic and verify that what i have removed is correct please.
Attachments
Spencerleehorton
Well-known member
looking through and comparing neve to audio maintence schematics BA192 has one difference, R8 on Neve is 10k and R75 which is same as R8 is 100k?
which is it?
Well it seems to me to be 100K so, ive found a few errors in cross referencing the schemtics and this error is repeated on both of the same parts of the circuit as well as another resistor which will need to be changed for 100k, both BA191 and BA192 have these errors so i'll change this tomorrow.
Now going to go through the other two cards for possible schematic errors, then update all BOM.
which is it?
Well it seems to me to be 100K so, ive found a few errors in cross referencing the schemtics and this error is repeated on both of the same parts of the circuit as well as another resistor which will need to be changed for 100k, both BA191 and BA192 have these errors so i'll change this tomorrow.
Now going to go through the other two cards for possible schematic errors, then update all BOM.
pvision
Well-known member
Rob Flinn said:
£44-odd from CPC Farnell, 6 in stock
£70 (+ £15.95 delivery from the USA) from Farnell, none in stock
The odd thing being that CPC and Farnell are the same company...
Nick Froome
Spencerleehorton
Well-known member
Yep, found the same errors in the Neve schematic and cross reference with the audio maintenance schematic, 100k on and 51k are wrong on at least 2 pcbs, so will change and update paperwork, then test.
Spencerleehorton
Well-known member
Not hearing compression now? I can see it all working but just can’t hear it?
Will investigate tomorrow
Will investigate tomorrow
Spencerleehorton
Well-known member
After much farting around I think I understand it a bit better.
In the ba183 it uses 100k for both r9 and r20 but in the ba283 it uses 10k and 51k.
This isn’t my problem though of why I’m not seeing compression on the output but seeing the GR meter moving?
Time to take it out of the case again and go through it all!!
In the ba183 it uses 100k for both r9 and r20 but in the ba283 it uses 10k and 51k.
This isn’t my problem though of why I’m not seeing compression on the output but seeing the GR meter moving?
Time to take it out of the case again and go through it all!!
Spencerleehorton
Well-known member
channel two is working but something isnt rightm the waveform keeps jumping around and its not consistant, also the level is way too high.
Im using all different transformers so going to wind 2 output transformers so i know that they are the same, then wind some more input transformers so i know that these are the same.
no point in going on if its all different!!
Im using all different transformers so going to wind 2 output transformers so i know that they are the same, then wind some more input transformers so i know that these are the same.
no point in going on if its all different!!
Spencerleehorton
Well-known member
I have wound all new transformers as most of the problems i was having, was due to miss match of transformers.
now getting good signal through both channels but I have had to take out of case again and layout on bench.
One channel is not compressing at all, and the other is but the threshold control has problems and its a bit hit and miss?
will look at signal going into BA191 and see if i can trace the signal which leaves the SC back into the Limit SC.
I think the signals output form the limit SC is (A) and goes back into the control Amp on BA185 by (M)?
is this where the compressed signal comes back in?
If anyone could explain the signal flow of the compressed signal please?
now getting good signal through both channels but I have had to take out of case again and layout on bench.
One channel is not compressing at all, and the other is but the threshold control has problems and its a bit hit and miss?
will look at signal going into BA191 and see if i can trace the signal which leaves the SC back into the Limit SC.
I think the signals output form the limit SC is (A) and goes back into the control Amp on BA185 by (M)?
is this where the compressed signal comes back in?
If anyone could explain the signal flow of the compressed signal please?
Spencerleehorton
Well-known member
one channel working great, the other ive got a problem with no compression showing on output but showing on vu meter?
Will record voltages and try and find out whats going on!!
Will record voltages and try and find out whats going on!!
Spencerleehorton
Well-known member
finally success!!!!
got both channels working and looking very close on compression and output, metering all good.
Just gotta get it all back in the box!!!
got both channels working and looking very close on compression and output, metering all good.
Just gotta get it all back in the box!!!
Youngwhisk
Well-known member
What correction needed to be made?
Spencerleehorton
Well-known member
well I'm not entirely out of the woods yet, channel 1 has a problem with the low end, so need to track down whats effecting it, seems its in the 112 part on the BA283, channel 2 sounds great but its too close to PSU so either need to put in some mumetal and shield the toroidal or move the psu out the box!!
The problems i had was a couple of resistors with cold joints and a 1.5k resistor R15 on BA283 wasn't put in!!
and also using a miss match of transformers and trying to get both channels matching!!!
Havent done adjustable attack yet, but threshold is good, release i have 4 settings, output is good, ratio is good.
Another weird thing is that when meters are set to input or output when i bypass/on it effects both channels?
don't know why this is, so will have to investigate but generally everything works now, its just little tweaks to get it perfect how i want it.
The problems i had was a couple of resistors with cold joints and a 1.5k resistor R15 on BA283 wasn't put in!!
and also using a miss match of transformers and trying to get both channels matching!!!
Havent done adjustable attack yet, but threshold is good, release i have 4 settings, output is good, ratio is good.
Another weird thing is that when meters are set to input or output when i bypass/on it effects both channels?
don't know why this is, so will have to investigate but generally everything works now, its just little tweaks to get it perfect how i want it.
Spencerleehorton
Well-known member
Still haven’t figured out what’s going on with how the signal is getting to ch2 when only put in ch1 but I’ve found a few more mistakes and ch2 is nearly there.
More investigation needed!!
More investigation needed!!
Spencerleehorton
Well-known member
Ok, one of the problems sorted, one of the txf was wired incorrectly so it didn’t have the inductance there and was cutting the bottom end!!
Neat way of HPF!!
Now to mumetal the toroidal and see if that cures hum and then see why ch1 signal is appearing on ch2!!!
Neat way of HPF!!
Now to mumetal the toroidal and see if that cures hum and then see why ch1 signal is appearing on ch2!!!
Spencerleehorton
Well-known member
Just two problems now, hum on ch2, will trace all wiring and see if I can find fault and will run just one channel from psu to see if is problem.
Nearly there now!!
Nearly there now!!
