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The 4 x 1084s in their Rack  
The 1084 LH Side  
The B283 Card in its Original Status  
The B182 Card (Solder Side)  
The B194 Card (Solder Side)  
The B205 Card (Solder Side)  
The Module Smoothing Caps  
The B283 Card Fully Re-Capped  
Servicing a set of Neve 1084 Mic Amplifiers and EQ units August 2013.


This racked set of 4 Neve 1084s have been in a studio for years and after being in a small fire within the studio had suffered smoke damage throughout.
They are in need of checking as they are old and their functions are not equal to each other.


Faults: Well - Each module needed checking individually. Initially the main and sub switches were all set to 'Off' levels. Module 3 showed that someone had re-aligned the setting knobs for the HF and Mid main equalisations 2 clicks above the STOP 'Off' positions. The knobs were undone and re-aligned properly.
With everything set to the 'Off' positions each module was checked in the 'Line' setting using an Oscillator, DB meters, Osciloscope etc. at a fix 2KHz frequency (module 1 was taken as the mean 0db level). Readings for EQ 'Off' and EQ 'On' were taken - quite dis-similar.


Each module was taken in turn - The HF main switch on module 1 showed that at the highest setting - without the calibration knob being involved - the sound was accentuated - inspection showed its associated poly cap soldered to the main switch had an incomplete solder joint to the common rail - once re-soldered - it operated fine.


Initially, all switches were cleaned and lightly re-oiled.
Decision Time - these modules are built as capacitor / resistor switching networks to alter the EQ throughout.
The majority of the powered cards have very old Electrolytic Capacitors and the dreaded Tantalum Capacitors as Input/Output de-couplers.
These all needed one to one replacement.
It was interesting to find that 'Someone' had changed some of these for "maybe" equivalents - but had forgotten to change the same items in the other cards.

What a mess!! Start again - find the circuit diagrams and replace all Electrolytics and Tants with proper items.


Firstly, Change all the Rack PSU Electrolytics - Nice smooth rails now!

Next change all the smoothing caps in each module - to save space - 4 x 470uf caps have been installed in parallel within each module. These were replaced with modern units - including replacement of a seperate individual smoother feeding each Mike amp board.

Now for each of the B283 and B284 Cards. What discoveries: some Electrolytics soldered the wrong way round - but still working as capacitors without blowing up their associated resistors.
The 20KHz mod for the B284 Cards was also implemented -


All of the Poly caps were tested - and were left on board as not needing replacement. Transformers checked for continuity - all OK.


Reconstruction of each module and re-installation - Let's take some measurements with everything set Flat:

Job Done! This multiple unit operates very nicely - Module 4 has some High HF problems which I will have investigate later - as the Client wants the unit back for use this week -
 
The Rack Power Supply - Caps being changed  
The 1084 RH Side  
The B284 Card in its Original Status  
The B182 Card (Component Side)  
The B194 Card (Component Side)  
The B205 Card (Component Side)  
The B283 Card (Solder Side)  
The B284 Card Fully Re-Capped  
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