Giving my old Ampex 440B warhorses a re-capping... 440C pcb are here

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gar381

Well-known member
Joined
Jan 27, 2005
Messages
1,226
Location
Retired in (Amherst) Cleveland, Ohio
I decided last winter on a cold snowy day that
it was time to recap my old warhorses (my Ampex 440Bs)
Here at the BI Test Kitchen.

machines.jpg


I started with the PWAs…

On the record PWA:

The Record card has a dangerous tant cap.. C32.  If that bugger goes bad it
Will take out the record head with it…. NOT GOOD !!  If you only
Replace one cap in a 440, MM1000 or any Ampex machine that uses this PWA
it’s this guy. The one in circled in RED.
I used a 22/35 Nichicon cap.  Mouser part# 647-UPW1V220MDD

Vishay now makes the old Sprague TE series caps, the silver Alum. Electro. guys On these PWAs.

Replace C28 with Vishay 10/25. Mouser part# 75-TE1204-E3

Ampex440_REC72.jpg




On the reproduce PWA:

Replace C8  with Vishay 50/50.  Mouser part# 75-TE1307.
Replace C13 with Vishay 50/25.  Mouser part# 75-TE1209-E3

Ampex440_Repro72.jpg




On the Bias PWA:
Replace C44 with Vishay 50/25.  Mouser part#  75-TE1209-E3

Ampex440_Bias72.jpg



Next is the Electronics chassis output cap.

Remove the 2 screws on each side that hold the back panel in place.

Ampex440_rear_shield72.jpg


Remove the screws on the top and bottom of the Black U shaped shield
And expose the back of the PWA connectors.

Ampex440_rear_cage72.jpg


The big 40+ year old yellow Sprague ATOM 250/50 cap is our new victim.
Ampex part # 5C-15

We could use an axial like the original but one of the nice guys on the
Ampex mailing list  suggests to use a Nichicon Radial 470/50
Mouser part # 647-UHE1H471MPD.  You got to move some wire around
To replace this guy plus I used a drop of RTV to hold it in place
but this is how it looks:

Ampex440_New_outcap72.jpg




 
The first thing I did was see what/where these guys were
Buy checking the skitz..

Ampex440_caps72.jpg


Here is C34:

Ampex440_C34SCAN72.jpg


This guy is a single section 1500/40
Also note that one of the C33 sections marked with the half
circle in this skitz is 350/35.  These look like the main
PSU filters caps for the channel module.

Also note that R73 the 750R 1w is on the sub assembly.


Here is the rest of C33 (total of 3 sections):

Ampex440_C33SCAN72.jpg


Section 2 marked with the Square is 750/25
Section 3 marked with the triangle is 250/25

Also on the sub assembly:

CR8 diode
R78  4700R  ½ watt

This skitz is connected to the Bias PDA backplane connector.


Here is C9 (total of 4 sections):

Ampex440_C9SCAN72.jpg


Section 1 marked with the flat line is 35/50
Section 2 marked with the triangle is 35/50
Section 3 marked with the half circle is 100/50
Section 4 marked with the square is 100/50

Also on the sub assembly is:

R16  15k  ½ watt
R17  15k  ½ watt
R19  10k  ½ watt
R20  10k  ½ watt
CR3  diode
CR4  diode

This skitz is for shifting the repro EQ for  HI-LOW
Transport speed changes.

Time to design a PCB to replace the whole Ampex sub assembly. :)
 
Well here is how it all lines up:

Ampex440_CAPS_OVERVIEW72.jpg


Note that the new PCB includes all the Caps, diodes, and resistors that were
On the subassembly.

Next step is stuffing 7 PCBs...
2 for my 440B-2,  4 for my 440B-4, plus 1 for my spare channel.
 
Here is the BOM for the new PCB:

C34 1800/50 Mouser part# 667-EEU-FC1H182
C33 half round 390/50 Mouser part# 667-EEU-FC1H391
C33 Triangle 270/50 Mouser part# 667-EEU-FC1H271
C33 Square 820/50 Mouser part# 667-EEU-FC1H821
C9 Flat line 47/50 Mouser part# 667-EEU-FC1H470
C9 Triangle 47/50 Mouser part# 667-EEU-FC1H470
C9 Half circle 120/50 Mouser part# 667-EEU-FC1H121
C9 Square 120/50 Mouser part# 667-EEU-FC1H121

All caps Panasonic FC

R16,R17 15k Mouser part# 273-15k-RC
R19, R20 10k Mouser part# 273-10k-RC
R73 750R Mouser part# 594-5073NW750R0J
R78 4.7k Mouser part# 273-4.7k-RC

CR8,CR3,CR4 1n4148

Terminals 11 per PCB Mouser part# 855-H2039-01
(terminals updated 2022)

Stuffing order:

Stuff the Terminals on the BOTTOM of the PCB first
Stuff the Ds, Rs then the caps

Next cut some 1/2” x ¾” alum. Angle stock from Lowes/Home Depot
1.9 Inches long. Drill holes to mount the PCB on and Tap some 6-32
holes to mount to the Ampex module.

Ampex440_Bracket72.jpg


L_bracket_440BFlat.gif


Completed PCB assembly should look like this:

Ampex440_PCB_stuffed_top72.jpg
Ampex440_PCB_stuffed_bot72.jpg
Ampex440_PCB_bracket_mounted72.jpg


Now for the installation in the Ampex channel chassis
 
Last edited:
The first step in the chassis installation is remove the top and Bottom
Covers of the Ampex chassis. Flip it on its top so the bottom wiring
Is showing.

Cut the wires at the terminals of the Ampex sub assembly.

Ampex440_cut_wires72.jpg


Unclip the wiring harness from each side of the sub assembly.
Remove the 4 6/32 screws that hold the sub assembly in place
And remove the sub assembly from the chassis.

Bolt the PCB bracket to the 2 holes closest to the bottom of the
Chassis with the terminals facing you. Prep the wires for soldering
To the terminals and solder away.

Ampex440_wire_prep72.jpg


Note there are 4 red wires. Solder 2 to each of the red terminals.
When you get to the terminal marked purp this wire maybe purple or tan.

Here is how it should look:

Ampex440_BOTTOM_WIRED72.jpg


Ampex440_TOP_WIRED72.jpg


If you reassemble the chassis you are done but while its apart you may as
Well change out the made out of un-obtainum Drake red record and yellow
Lites for something more modern. For that matter get rid of the sylvania
Meter lights as these guys are also made out of un-obtainum.

Here is what I did to replace the meter lights:

Ampex440LED_meter72.jpg


I wired a pair of white LEDs in series with a dropping resistor. Soldered
Them in the sylvania pin sockets so I could use the sockets in the mounting
Clips on the meter. While not the most elegant solution, this worked great !

As for the record and ready lights, Dialight makes drop in replacements.

RED… 507-4761-3331-500F
YELLOW… 507-4961-3333-500F
(#s updated 2022)

These are polarity sensitive . If they don’t work first time just spin them
180 deg. In their sockets and they will work fine.

Here is how my 4 track looks all lit up:

Ampex400_finished72.jpg


Note that these posts at time sound a little assembly manual-esk
I have been writing lots of manuals lately and kind of fell into it.
If you want to do these updates to any machines you may have I do
Have a few extra PCBs .. Shoot me a PM. BTW.. these PCBs
Will work for 440(A), 440B and MM1000s I don’t know if they
Will work for 440Cs as these guys are a different animal an I have not
Researched it.

GARY
 
Last edited:
Up date on PCB availability ...

Our fine friends at the Ampex Mailing List bought up
all my extra PCBs.  I have ordered 60 more from my
board house and have a waiting list started.  If anyone
here would like PCBs PM or email me and I will put you on
the list. :)


Note.. I am permanently keeping BOTH 440B and 440C IN STOCK !!
PM me to purchase.

GARY
 
Gary,

That is so great. I just PM'd you regarding getting a few of those.

Have you recapped the power supplies yet?

I loves me some 440

Jon
 
gar381 said:
BTW.. these PCBs
Will work for 440(A), 440B and MM1000s  I don’t know if they
Will work for 440Cs as these guys are a different animal an I have not
Researched it.

GARY

UPDATE

Rick Chinn  over at the Ampex Mailing List has kindly researched
The 440C capability issue with this PCB.  By modifying the way the board is
stuffed  by basically leaving out a few parts and putting in some jumpers,
the PCB would work Electronically.  BUTT ... There is physically not enough
room for the  PCB as the 440c chassis is laid out very differently  than the
440B chassis.  For you 440c owners who wish to do this re-capping,  I will
be designing a simpler-smaller PCB that will do the Job  in the next few weeks :)

Stay tuned

GARY

UPDATE #2

440C cap PCB is at the Board House!!

I will start a new post about  the installation soon. :)

GARY
 
Thanks for posting this!
I'm just in the process of re-juvenating a MM1200.

I didn't  know about that nasty Tant on the record PWA cards, thanks!
I haven't found any dead tants yet so was going to leave them... But i'll defo change these .

Recapped the PSU on friday and will be getting on to the audio cards Monday.
Replaced lots of bearings and beefed up the MDA card so hopefully it'll be fairly trouble free.

Just hope the heads are ok... They're not open circuit and look pristine.

Hoping to make the first recordings in December!
 

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An variation has surfaced to the 440B and I Think this also applies to the "A" as well.

if you have a chassis with 3 Orange wires hooked up to the terminal strip ...

440_ORN_WIRES.gif


you can still use the 440B pcb.  Just download this pdf:

http://gar381interests.com/440B_Cap_PCB_ONR_WIRE_VAR.pdf

Also the 440C cap pcb is now available and you can download the instruction
manual here:

http://gar381interests.com/440C_recap_manual.pdf

At this point this  is probably a Black Market thing but I will try
to keep these 2 pcbs on the shelf for anyone who needs these guys.
$15 per channel post paid to the lower 48 and plus postage elsewhere
in the world.  Just shoot me a PM or email.

GARY
 
Hello, brand new member here. I know this thread is old, but I'd also be very interested in the PCBS for the 440c if there are still some available. Thank you!
 
Hi!
My apologies, I'm not seeing how to PM you directly -- I'm interested in purchasing a pair of your PCB's for a 440B. Thank you!
 

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