Soundtracs Topaz
Repairs & Modifications

The Audio Signal Path

The Channel Input / Output Module Signal Path


The Masters Section Signal Path

tsigflow 02

The Schematics

Topaz Schematics pdf 01
Topaz Schematics pdf 02
Topaz Schematics pdf 03
Topaz Schematics pdf 04

Internal Images (uploaded by a member to the Topaz yahoo group)

tpzint1 tpzint2
tpzpcb1 tpzpcb2

Replacing the 100mm  Faders

Topaz faders on the board (picture from a smokers Topaz)

topaz fader
The Factory Topaz Fader

Topaz Fader Dimensions
Length = 5.039" or 128mm X Width "Wide Body" = 0.591" or 15.00mm X Heigth = .315" or 8.00mm

for all potentiometers sliders, mono & stereo, as of APRIL 2013.

Panasonic Discontinued Potentiometers

fader           alpfad
Panasonic Fader PJQ100SD-ND          ALPS Fader RSA0N111900Q
** OUT OF PRODUCTION **             ** NOTE T-arm LEVER **

This means the end of production for the Panasonic Potentiometer that was the choice replacement for the Topaz
Panasonic 100mm "wide body"10KA (LOG) mono fader...DigiKey part# PJQ100SD-ND

For replacement of the Soundtracs Topaz, Project8 & MAXI faders you can use...
ALPS 100mm Potentiometer Sliders

fader lever
The Fader's Lever

The 100mm ALPS fader will work as a replacement. Though the ALPS lever is a T-arm configuration, which doesn't stand high enough through the mixers exterior fader's slot, nor will the fader caps mount correctly onto the T-arm lever. The procedure to modify the ALPS potentiometer is to open up each of the fader's housings both ALPS and Factory Topaz fader and swap out the ALPS T-arm lever with the original Topaz factory fader's lever. The levers are held in place by the fader's housings & aligned internally to their respective wiper.

Make sure to place lever in same position relative to wipers.

I would order an extra ALPS fader or two to understand the repair and give yourself some room for error the first time you attempt the lever transplant.

Use the faders soldering points as a way of lining them up so you know the top end from the bottom end of the fader / potentiometer. Align the lever correctly and make sure that the lever goes back into the new fader the same way as it came out of the old.

Keep the stereo fader's levers stereo, & mono fader's levers mono, the two different types of faders & their levers are interchangeable.

Replacing the Potentiometers 

From the Soundtracs Topaz Production Console Operating Manual Schematics & Parts List: page 4

I have two seperate schematics sets; the first, P9AN245BL which is the parts list from the printed manual I own.
The second, P4AN2951RT is from the schematics I downloaded from the Soundtracs Topaz Yahoo Group Files.

toppots Parts list revisions...
P9AN2454BL / P4AN2951RT

Stock Number                         Description
POT000106  /  POT000147     .5K REV Log C VT/Single                                     
POT000107                           .10K LIN B CD V/Single
POT000108                           .50K LOG A V/Single
POT000109                           .100K+100K REV LOG C V/Dual
POT000110                           .10K+10K LIN B CD V/Duel
POT000135                           .EVAJQ4R17Y14 10Klog FDR

For standard replacement of your mixer's potentiometers use 
Alps Faders pots.
On the Soundtracs Topaz Schematics you will find the Stock Number next to it's PCB address marking.
These stock numbers on the schematics are hard to read, the copied text is bleeding together.

Replacing the Push Buttons

topbut topbut3 topzbut

The Diode Bridge on the internal Power Regulator Board


One thing that needs to be checked out on your Topaz once you have it openned up is on the internal power regulator board. This board is the one attached with heat sink to the bottom panel of your Topaz. On the newer Topaz Project 8 mixers you shouldn't have anything to worry about, but if your Topaz is of the original inline miami style, then you should check to see if the doide bridges, BR1 and BR2 on the internal power regulator board are GBPCXXXX type Diode Bridges. The old components will be labelled KBPC25-02 , the newer component replacements will be marked GBPC3502. If the diode bridges on your internal power regulator board is anything other than a match to the old part KBPC25, or the real old grey type, they should be replaced with the GBPC type.

Diode Bridges

GBPC3502's are the suggested replacement part for the diode bridges, you can also use;
2502, 2504, 3504.
3504 is a bit overkill. The newer GBPC components are glass passivated.

If you have noticed that you have lost the +/-17 volt rail (power) to your Topaz, which will be visable by the loss of the LED indicators found in the upper right hand side of the Topaz' master section, it means your diode brige has failed and is in need of replacing. The 48v rail is dependent on the 17v rail. So before replacing the diode bridges you may need to check out and possible replace the power regulators LM317K or LM338K (see power regulators below).

You can get the diode bridges through 
Mouser part#621-GBPC3502.

other online locations that might also carry the diode bridge component...


eBay GBPC3502      gbpc3502

Power Regulators

While you have the internal regulator board out, check out the power regulators.

If the regulators on this internal power board are in need of replacement, go with LM317K for the Topaz 24 & LM338K for the Topaz 32. The original stock parts were made by STMicroelectronics. So look for the real deal LM338K REGULATOR LOW DROPOUT ADJUSTABLE 5A ST MICRO 338 LM338K, not the crap from HK. You should pay between $8-10 each.

eBay LM338K or Mouser    lm338k

Upgrades, Modifications & online musings

I have come across on various web forums conversations pertaining to increased fidelity of the Soundtracs Topaz. These exerpts are from conversations that can surely still be found on the net. Please note that these are fractured ideas that I have not tested nor do I promote or advise, but they are no doubt interesting. As I investigate these potential ideas I will certainly publish my finds.

OpAmps and the Topaz Mixer

if your Topaz mixer has got TL071 or NE5534 you could upgrade to:

OP 42
OPA627 etc.

These are all single op-amps. Op amp upgrades will give you a little more headroom and a little less distortion. Use Panasonic or Nichicon caps. Use Wima caps on the EQ's. But I don't think it's worth upgrading unless there are problems. The Topaz console could wind up sounding brighter, harsher or darker. You could wind up with undesirable HF oscillations. Then you gotta start adding blocking caps etc.

Try the console as is first. Try 1 channel only. See if it makes a difference. Do a blindfolded test! We get caught up in this surreal world that a chip or cap or transformer upgrade will make everything sound helps, but it's no miracle.

Keep in mind, I had read that the new Toft ATB is using TL072.
Even the MTA-90 large format console uses TL072 IC's.

If a lot of channels have IC's out or intermittent, then change but otherwise, get to know your board first. If the circuits were designed around a particular chip swapping can cause more harm than good.

Now having said all that...You could start the upgrade in the master section first. Summing amps and so forth.

Remember these chips can cost between $1.50 to $18.00 each.
It adds up pretty quickly when you've got 10-25 per channel!

Rechipping / Replacing the OpAmps found on the PCBs.

Idea#1: An online Topaz owner stated : that he's got a Topaz here that he rechipped with JRCs. He also modified the power supply board. Sounds much smoother now, a bit more open, and quite a bit punchier. He highly recommend the modification. It really takes the stock Topaz sound up a few notches.

Idea#2: An online Topaz owner asked : A Soundtracs Topaz 24 channel/eight buss, that has TL072/074 throughout the channels and NE5532 on the master summing. It uses a +/- 17 volt @ 1.5amps power supply. The Topaz uses generic electrolytic capactitors throughout the boards components. Wondering if there is any benefit in replacing the opamps with OPA2604/OPA2134 or similar opamps. I would likely have to upgrade the power supply. Also it is worth it to re-cap the console with Panasonic electrolytic caps?

Answer 1: Try using Burr-Brown chips, you will need a scope to determine if the opamps are stable. Adding some .1 uf mono ceramic caps from the opamp's power pins to ground is helpful. (Please note : that adding ceramic caps is where an amature in modifying electronics can get into alot of trouble and mess up, Big Time!)

Answer 2: This console has been redone with LT1358's for the duals and LT1359's for the quads. Increase the coupling caps. Bypass with polyprop film caps and you will open the console up (get more headroom).

Idea#3: An online user asked : I have read some other chatter talking about the merits of the LT1469CN8 from Linear Technology, SSM2135, and other manufacturer 5532 (JRC 5532D, and 5532 from Philips or Raytheon). Have you had any experience and/or thoughts about these chips as replacements for the stock 5532 in the Topaz? Also... can you share some specifics in cap type/brand/value you use in your mods as upgrades to the stock Topaz.

Answer : I have replaced mostly with either Panasonic FM, Nichicon HE, Rubycon Z or Black Gates. All require a film bypass cap. Try the LT1358 against those others. Like when your ears pop after landing in a jet. LM6172 is very good but somewhat tougher to stabilize.

Question : Any tips or suggestions with the Topaz I should be aware of, like buss levels or headphone feed setups.
Answer : The only thing we did to our Topaz is change the jumpers to +4 instead of -10.

Idea#5: Replacing the 4 SSM2017 preamp ICs with sockets in order to play around with different types of preamp chips. Currently I have 2 SSM2019's and 2 THAT 1510's residing in the sockets. On a first power up the chips sound pretty decent, the THAT 1510's had much more available gain.

To note, it can be difficult desoldering the Topaz IC's, recommend using a wick over a desoldering gun.

more Soundtracs Topaz pages...

Soundtracs Topaz Information

Soundtracs Topaz external PSU replacement

Soundtracs Topaz meterbridge VU meters & lamps

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