NEVE 1081-Switch assembly/Pot idea & new comp. placement

[nrgrecording]

Hi guys.

Some time ago I recovered some red pcbs...
As far as I know nobody get them working right? Me too. :wink:
But I decided to get them wired and populated... so my children can do the rest or so. :green:
This week I found a solution for the switch assemblies...

The problem is:
The knobs (gain) are made for ca. 3mm potentiometer shafts (so it is possible to use a 6mm knob for the outer ring (frequency).
But where to get potentiometers with a 3mm shaft? Hmm.
Maybe the original knobs are 3,2mm? Otherwise the knob would became a bit "shaky". However... 3mm 3,2mm pots are hard to get. I think piher makes them. But I bet the pots are hard to get.. no standard stock... maybe only available in bigger quantities... AND... if you need a spare pot... :?

My idea is:
I visited a friend who have a 'lathe'. Nice machine!
We used a 12mm aluminium 'bar'. Drilled a 3,2mm hole at one side, 3mm hole at the other side... two holes with a thread for the grub screw... and it works perfectly. I used a 3,2mm metal bar for the potentiometer and sand the tip down to 3mm. So I can use every 6mm potentiometer I can find. I think the original one uses center detent potentiometers, right?

Another idea could be:
Buy the normal adapter (made by mentor for example)... They're available with 6mm to 4mm... and grossly negligent tape around the bar to get 3,2mm.
Maybe not hi end... but could work. The tape will fix the bar to the middle.

Nothing fancy... but maybe it helps.

some pix:

----------------------------------------------------------------------------------

Peter was nice enough to send me a 1973s manual of the 1081... thanks! So i checked the partslist, partslayout with the manual... and made a component-placement file with all the component values on one page.
I don't know yet if the changes are correct... we will see...
I thought about buying some LIYY cable. I found some 10x0,14wire... but i think the cable is available with more wires in one cable... the DIN standard says that this cable have the correct colour code like the original neve units... (i think). So maybe useful for the switch wiring. It could avoid wiring errors. Thats the reason why i added the colours to the component placement...

Here are some changes: (not checked)
-capacitors at the back of the discrete amps (also found in older manuals)
-added 47k resistor (R14 on partslist rev3)
-anode marking at the amps
-10nF cap on BA338 (was 10pF)
-10nF cap on BA308 (was 10pF)
-1R5 resistors at the output stage of BA340 (was1005
-47k on BA340 (was 4k7) 2x
-36k on BA340 (was 6k6)
-changed polarity on tantals
-10µ/25 tantal instead of 0,1µ on BA340
-Pin numbers at amps marked for easier maintenence (see neve documentation)
-470µF cap changed to 25V (was 16V)
-some electrolytics marked with audio and psu
-colour code for cables added
-1K5 resistor value added
-some blue resistor values are beside some resistors.. these are the values i'd found in the old documents
-added orientation of inductors
-one cap is 150µ/16V .. was 100µ/25v (near output)
-filter caps was wrong... 220nF (was 22nF)
-filter cap was wrong... 47nF (was 470nF)


If someone has any infos... let me know... i will try to collect every helpful information i can get. Maybe it is a good idea to collect all the changes in one pdf... i don't know.

here is the pdf:
http://www.nrgrecording.de/NEVE1081_2.pdf

Regards,
Frank.

 

[Neeno]

[quote author="nrgrecording"]
Nothing fancy... but maybe it helps.
[/quote]

Nothing fancy ?
FRANK... YOU ROCK !
That's really helpful !
Thank you !

:guinness: :guinness: :guinness: :guinness: :guinness: :thumb:

 

[Kev]

Yes
Frank does rock
:roll:

:thumb: :thumb:

 

[fuzzbox]

Thank you thank you thank you
Frank you do rock!!

 

[matthias]

ach du lieber vadder...

 

[ToroRojo]

Awesome. Good Job Sir! :guinness: :thumb:

 

[quadwould]

Modesty man you are Frank!!!!


you sure do rock!! :thumb:

 

[rafafredd]

Man, that´s a lot of work, and lot´s of help!

 

[tommypiper]

Vielen Dank, Frank!

Another solution might be to drill out the knob? One step solution. I don't know if that would solve the problem. I recall Jonathan saying something about the knob holes being made small and Sound Guy was talking about drilling them a while back.

The PDF is awesome, thanks for all the corrections. Yes, it would be a good idea to get all the changes and corrections in one PDF!

Question: What are you using to mount the input trafos? I've been thinking of doing something like that from sheet metal. Did you make that metal plate?

cheers!

 

[nrgrecording]

[quote author="tommypiper"]Another solution might be to drill out the knob?[/quote]

Yes. Thats a good idea of course. BUT... I don't have a bunch of spare neve knobs... and so it's better to touch the knobs with velvet gloves and not with a drilling machine. :green:


[quote author="tommypiper"]Question: What are you using to mount the input trafos? I've been thinking of doing something like that from sheet metal. Did you make that metal plate? [/quote]

I bought two BA340 output amps from Cyril (Raindirk). (because I couldn't find any heatsinks for the two output transistors.. and i liked the original style of the output amp... what a beauty! ok... we'd been told BD135/BD136 will work here.. but that was after i bough the 340amps)
And I got two metal plates for free from Cyril and some B6A? screws.
Attention... the transformers don't have standard threads of course. :wink: But the carnhill transformers have two screws at the top where the connections have to be made... if you don't tell anybody... you can steal the two screws. :roll: the screws normally fix the connector panel to the transformer... but its glued to the transformer.
The metal panels I have don't fit exactly to the 1081 pcb... still need some work. But this kind of metal mounts... 90° angled metal... is easily available at building centers.. so everyone can make his own transformer mounts easily.
Some sheet metal from the framework for plaster boards of a drywall construction could do the trick maybe.

here is a picture of the original mounting-plate:

by the way... here is a picture of the output amp...
We have to be careful... The case of the transistors must not be connected. So plastic screws and some isolation to the heatsink is needed. The heatsink is also fixed to the pcb with a threaded bolt.

 

[Tekay]

Do you have to lift of the heatsink to reach the bias trimmer?

 

[Zee1usa]

Thank you Frankenstein ! :thumb:

 

[nrgrecording]

[quote author="Tekay"]Do you have to lift of the heatsink to reach the bias trimmer?[/quote]

No - because.. there is no trimmer. Seems to be fixed with two resistors instead of the trimpot. The pcb layout is also double sided... i think the original ones are single sided, right? 1970.. double sided pcbs...? I don't know... As far as I know Cyril did some servicework and had to repair some neve stuff... so maybe he made some amps himselfs?
Hmm... the BA340 is a class AB push-pull emitter follower? With the trimmer you set the level WHEN both of the complimentary transistors are going "on"?
So you can adjust between a hot and cold heatsink? :roll: :wink:

something like this... (direction of pots may be different)
trim pot counterclockwise:
big distortion
hot output pair
class A

trim pot counterlockwise:
big distortion
cold output pair
class B

So the adjustment procedure is to start at class B, turn the pot and look where the distortion is at a minimum, right?

 

[Tekay]

How many diodes is there in your output modul? if 2 diodes and no trimmer it's probably a 440 instead of a 340?
On the BA440 the trimmer was changed to two resistors instead, the upper is 220ohm and the lower AOT(only seen 220ohm there too), and the BAX13 from TR1 base to TR6 emitter was removed.

 

[nrgrecording]

Hi Thomas,
ahem... yes its a BA440! Thanks for the information. Those BAxxx drives me crazy :green: But I read that sometimes BA440 were used at the 1081, too. I'll try to plug in in the BA440. Or isn't this recommendable?

 

[clintrubber]

Looks very nice all this !

Just wondering, are those red clamps for the output-devices to the heatsink old parts or are they available somewhere ?

Regards,

Peter

 

[Tekay]

You can use both BA340 and BA440 in the 1081, or the IC based BA640!

Must finish mine soon too! Must etch some 338 pcb as I ony have one original, have plenty of the 438 both they wount fit as the 338 got this extra pin for output stage boost! Which didn't work out as good as the Neve staff thought regarding to Geoff Tanner! :?

 

[nrgrecording]

[quote author="clintrubber"]Looks very nice all this !

Just wondering, are those red clamps for the output-devices to the heatsink old parts or are they available somewhere ?

Regards,

Peter[/quote]

The heatsinks i have are old parts.

But Thomas had a nice idea with using BD139/BD140. One picture says it all:

I think Tommypiper bought standard heatsinks from Digikey or mouser which appear to fit...
I searched in my digikey catalog and found "hs255-nd" for 9,21? :shock: :green: but... the width is 19,05mm. Seems that this won't fit.
BC441 and BC461 are TO-39 i think. I got my heatsinks already, but maybe anotherone could help here?

 

[clintrubber]

[quote author="nrgrecording"][quote author="clintrubber"]Looks very nice all this !

Just wondering, are those red clamps for the output-devices to the heatsink old parts or are they available somewhere ?

Regards,

Peter[/quote]

The heatsinks i have are old parts.

But Thomas had a nice idea with using BD139/BD140. One picture says it all:
http://www.vintagedesign.halmstad.net/images/BA440TK400.jpg
[/quote]
Thanks for the info.
Don't know those circuits, haven't had a look at these, but was interested for some other kind that uses TO-39 as well. So as it seems the '139/'140 can be used - indeed a lot easier for attaching a heatsink :thumb:

 

[tommypiper]

[quote author="nrgrecording"]I think Tommypiper bought standard heatsinks from Digikey or mouser which appear to fit... [/quote]

Yes. I have photos, if someone can host. There are two I have tried that work. One is more tall, one is more wide. The best may be one I call the "Nun's Hat" because it looks like a flying nun's hat. Mouser # 532-578305B00. It fits right on the transistor! I have photos of these sitting on a BA340 card. You can put two side by side without touching!

The second one I have which also fits is round and if you used two side by side they would touch (EDIT: and apparently you will need to use insulation to prevent electrical contact). They have three rings of heatsink, and if you use two of these heatsinks you'd have to fit them so the rings fit into each other's gaps, because the rings are a bit wide in diameter. It may have a better heat rating than the "Nun's Hat." Mouser # 532-322805B00.

I didn't know that the two transistor cans need to be electrically separated from each other? What about Thomas' heatsink? Seems they are electrically contacted through the heatsink there? (EDIT: OK, I can see there is a round insulating pad under the left transistor. But the screws on Thomas' heatsink look to be metal?)

Anyway, these heatsinks from Mouser should be a very simple option for use on the original type transistor cans.

If someone can host or tell me how to post photos I will put some up.