TAC 16-8-2 restoration.

Hi guys,

This will be a journal I guess...  my first complete console restoration.  A TAC 16-8-2 with 8 channel extension.  Hopefully somebody will learn a thing or two from my mistakes.  I will haha.  Deadline June 21st.  I have no schematics/manuals atm.

Just got the console tonight.  Fired up the PS, checked it wasn't blowing fuses, then connected to the desk.  Lights on, yay!  Connected some signal and tested channel 1 and master.... Sound!  Hoorah.

Where to start?

Have created a spreadsheet of all functions of the console and am testing them one by one.  Will upload when I'm done.  I've found that if a function is dodgy, pushing the associated button repetitively while my girlfriend laughs at me seems to fix it.  Then I can be all like, 'See, I told you so'.

Any one have any tips for cleaning contacts of switches and pots? 

Thanks!
Arie.

Finish testing channels.
Anomalies

Very noisy with faders and gain up.  Buzzing, and loud hiss????  I have read using a newer op-amp can reduce noise.  Is this true?

Crackle when channels 17-24 tapped.

Bus 6 is dead.

When selecting more than one bus and monitoring only through master, makes signal quieter...

When engaged, channel 3 EQ makes Audio very quiet.  Low pot very scratchy.

Cross talk is high.

Thanks,
Arie.

This is a very large project. Consider the value of your time, mabye get a Mackie and start making music tomorrow ;D
Othervise take the whole thing apart, change all the el. caps, change all noisy pots and switches. 4 weeks of hard work.
http://www.audiomaintenance.com/acatalog/index.html will be your best friend.
Is it the Blue desk? I realy thougth it was a great desk when it came out in the early 80s.

j

Hi Joe!

Yes.  I've recently shattered my shoulder, so I have a lot of spare time, but only one arm!

I've identified all the noisy little bastards tonight... Is it worth trying to clean the scratchy pots/switches before replacing them?

It is a blue desk.  Seems like thats the general consensus.  I am only a little worried about the noise floor... at the moment anyway .  We'll see what its like after the recap.

Thanks,
Arie.

I'd start with a recap of the power supply and put some low ESR, 105 degree caps in there. Look also at reseating the regulators and power transistors with new insulators where needed and thermal paste. Get all the dust out and possibly even go as far as replacing the rectifiers and diodes with better spec/overrated versions. Also, make sure the connectors for the PSU are cleaned/de-oxed and that the mains cable (if captive) is replaced to ensure a good earth path.

A clean, well regulated, cool-running PSU will stand you in good stead for your console refurb. I've done a similar job before and it was immensely satisfying. And, there's nothing like seeing row after row of fresh Panasonic FC caps glistening in the wee twilight hours 

Hello, I have the AMEK TAC 16-8-2 full technical service/schematic manual. If there is some specific data you need at some point, drop me line.

You can also purchase the service manual from A.M.L.  http://www.audiomaintenance.com/acatalog/manuals.html

One of the challenges with the desk is the terminal buss board that spans the vertically mounted channel/group/master pcb.s (see photo)

It must be gently removed without overflexing, in order to access the channel pcb.s. The channel strips can then be removed individually for servicing after de-soldering  some wiring and removal of knobs/fasteners from the top panel. It is a labour intensive desk, but a labour of love to be sure.

Hi bob,

Just took a peek inside the power supply. 

2 x SIL.BRIDGE 12.5A/150V http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=261+198&x=0&y=0 (replacement??)
2 x 10000 uF 40VDC caps
1 x Unidentified cap??
1 x LM338K
2 x Covered power transistors??

3 x PCB boards labeled 179.  2 identical, 1 with electrolytic's + CR1?? on it. 

All looks very tidy and dust free.
I am a bit confused as of how remove the power transistors?  They're mounted to the sides of the chassis.

Hi envelope, thank you for the photos and the information.  I will have a look inside the console after breakfast and post back.  Is it possible that you have any schematics for the 16-8-2 in digital form?

Thanks,
Arie.

Dammit it sucks taking all these knobs off! 

Hi again envelope,

I'm having trouble getting the buss board off.  Does it slide off the contacts?  If so, its giving a bit of resistance!

Cheers,
Arie.

Never mind.  Brute force was the answer.  About to pull some channels and make a BOM of parts to order....

If anyone else is doing the same thing, the dual aux pot knobs are a bit tricky.  Pop the cap, unscrew it and pretty much pull.  Also a small socket set is great for taking the nuts off.  Common sense for some maybe, not for me  8).

What difference will it make recapping the smaller caps in the signal chain?

Will it help lower noise?

Thanks,
Arie

colonel_sanders said:

Never mind.  Brute force was the answer.  About to pull some channels and make a BOM of parts to order....

Click to expand...

Glad to hear you got the board removed......It takes as much pulling effort as any edge connector card, except that there are 26 of them to disconnect simultaneously!!!!, (without bending the board as the traces may fall off).

Getting it back on also requires some patience and a ginger touch. I started by lining up the bottom of each edge connector with the channels and applying a small amount of pressure with my thumb to each individual channel in succession until the board is fully seated with no bends. It's really hard to describe, but not bending the board is paramount.

I don't have any electronic documents, just spiral bound with 8.5" x11" schematic sheets.

I will later try to find some time to take scans of the input channel/group, but you will have to try overlap the images..to see the seams.

In the meantime, here is a scan of the power supply circuit. (it is on a single page)

Mean, that helps heaps.  Thanks envelope.

What can I use to replace the bridge rectifiers?

2 of the originals are SIL.BRIDGE 12.5A/150V from RS components.  They are long rectangular rectifiers with tabs, screwed to the chassis.  The other is a square soldered to a PCB.  All PCB's have a space for a bridge rectifier.

This is the only 'SIL' packaged bridge rectifier I can find http://nz.mouser.com/ProductDetail/Shindengen/D3SB20-7000/?qs=mr%2fYtQLfk961oQpp0UD5jg%3d%3d

Seems a bit overkill!

For any other Newb's out there, this is a great site: http://www.underthebigtree.com/wiki/tiki-listpages.php

I have not replaced those in my power supply, but the schematic should help. I'll look up the part numbers, when I get home. PM your eMail address, if you would like me to send scans when I get them. I do recommend buying the technical manual from A.M.L. 

Received panasonic FC/FM + chemi con power supply caps in the mail.  Have started recapping the beast.  Am also installing phase switches above the gain knob in channels 1-16 and am replacing the 'twisted' single core wires on the mic input and faders to twin core shield on the first couple of channels to see if makes an audible difference in noise levels.

Can anybody confirm the value of C19 on the master section as 10 picofarads?  Capacitor crumbled when i touched it ???

PM'd, thanks Envelope.

Thanks,
Arie

colonel_sanders said:

Can anybody confirm the value of C19 on the master section as 10 picofarads?  Capacitor crumbled when i touched it ???

Click to expand...

It is confirmed. C19 = 10pF

Thanks Stuart!

Will hopefully power her up tonight... Will post my results regarding noise level and sound after recap asap!

Thanks,
Arie.

Do you have any news on how the board turned out after the refurb?