Soundtracs Topaz hum and meterbridge problem

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feza

Well-known member
Joined
Jan 23, 2008
Messages
105
Location
Holland
Hey,


A couple of months ago I have bought an Soundtracs Topaz 32x8x2 with meterbridge. After a while the mixer started to give that irritating hum around 100hz. That peak is -40db so it always present in softer music passages.

I've recapped partially the powersupply and it improved but still that hum comes in randomly. When the peak leds (under the fader) are having a peak the hum will sound or will go away. That peak will lit a half second on all the channels, all the same way. When the unit is fully warmed-up the hum is away but still there is some fase in the sound. I see that fase in an analyzer and you can hear it. I'm thinking that the caps has never been replaced so I have ordered five new capacitors for the powersupply.

With the meterbridge it has a peak on all the channels (LED on the meterbridge) when turning on the powersupply. Didn't have that before replacing the worn-out caps inside the mixer. The orignals were 50v and I have replaced them with 63v, no problem right?

And by the way I cannot measure the powersupply. Atleast, not the capacitors. The connector will pop-out when the top of the mixer is lift. It's a very short cable that connects with the mixer itself, too bad.


Many, many thanks if somebody can help me with this! :grin:
 
Yo,

Thought that I post an update about this matter.

I've replaced yet again capacitors. Now 7 in total. But still getting that hum and 'peak-led' error. So there is still hum and goes away or comes in with the peak in the peak-led. There 8 more caps (Axial) to be replaced but have this feeling it won't solve it. The other things I tried was muting groups, channels and unplugging cables. Nothing helps. So after these final re-capping of the powersupply, it will possibly end of doing it myself and hate that. But today I will be removing the top panel to see what I can find.

I was hoping that there are people willing to help me. Don't you just hate when you cannot find the problem? Very frustrating you know. :cry:
 
HEy Feza

I had similar issues with my console (not the same one). Consoles are tuff to give help with and thats partly the reason no one has replied.

They are complex animals and they do more than one thing, unlike a racked piece of gear.

Eventually I sent my Console to a tech for service, its fixed now but here are some of the problems that you should look into.

1.Recapping the unit. (63V instead of 50V are fine as long as they fit)
2.do extensive testing on the PSU, make sure its fully regulated with no spikes
3.Use a scope and also a signal tracer to see if you can hear where the 100Hz starts becoming audible.
4. Check your chips and swap new ones in see if that helps
5. Don't try to "upgrade" the chips to BurrBrown or anything until the unit is fixed -- upgrading the Caps is fine though -- nichicon, Elna etc. but try to use Low ESR caps
6. Make sure the chips aren't oscillating
7. Make sure unity gain (0) is actually unity gain -- my fader buffer gain was very high on my console what I though was unity gain was actually something like +4, which subsequently increased the hum exponentially for every fader I brought to unity gain.

those are my suggestions, again I tell you this as a starting point, but a small problem can turn into a big one if you don't know how to properly test the unit. So be careful, don't disconnect things thinking you'll replace it - if you mess up you can be quickly digging a hole for yourself. schematics and reading schematics is really super important. I had 5 different versions of schematics for my console which was incredibly confusing.

Most importantly go super slow... quick fixes cause more problems if your not very familiar with the unit.

I'm sorry I can't help you more than that... I hope this wasn't a lecture
 
Hey,

Well. I've decided to let it be repaired by a professional. It's to much of a risk for me. I can be very stubborn and the mixer is still (almost) fine. Going to be very, and I mean, very disappointed of the mixer is broken. I want to make music, getting further with tracks!

So thanks for the advice. It's better to give the pro a peek. :thumb:
 
[quote author="lofi"]http://www.studiosystems.co.uk/

talk to Tim, hes a wonder with this stuff.

Iain[/quote]

That is a coincidence. Because of him I have bought the Topaz. :grin:

I'll keep that in mind....
 
Well I have contacted Tim. Explained the deal and gave me good advice. Paid for the 25GBP fee (that is optional) and have some nice Soundtracs database.

The advice he gave me will be forwarded to a tech. I just hope that will solve it. Very thankful that people like Tim are around. :thumb:
 
got to admit that try as i might i cant bring myself to sell my topaz, i love it.

i got two of the cpeq boxes as well, happy boy am i

Iain
 
Well, if the topaz was not used for a while before you bought it, it's nice to check all inserts, they tend to oxidize a bit.
That worked wonders on ours.
Next, is the hum on all outs?
Then I would assume it's the psu section that is a bit flakey still.
Not only change the capacitors but also the bridge rectifier to a higher rated/spec glass one GBPC something. They tend to fail on the topaz series.
Spikes on the meterbridge sounds odd, too.maybe a psu thing as well...
For grounding it may be cool tp do a starground scheme instead of the daisy chain that I saw inside the topazes - but i never had probs with that really...
all connectors in the internal psu section of the topaz (maybe really 'all' connectors) should be cleaned.

I hope Tim sent you some good info as well - a very helpful man indeed. :thumb:

Kind regards,
Martin
 
Thanks for the reply!

Yes Tim said that the problem lies with the internal PSU. The bridge rectifiers need replacement. I'll try to fix it myself, bare with me. :grin:
 
[quote author="lofi"]got to admit that try as i might i cant bring myself to sell my topaz, i love it.

Iain[/quote]

spoke too soon there!! few too many emithers to tim about a prob i had on one of the cpeq boxes i have and voila, i am now the proud owner of a Quartz :grin: :grin:

now to solder 9 sets of EDAC's

Iain
 
[quote author="lofi"]
spoke too soon there!! few too many emithers to tim about a prob i had on one of the cpeq boxes i have and voila, i am now the proud owner of a Quartz :grin: :grin:

now to solder 9 sets of EDAC's

Iain[/quote]

Man! A Quartz! Congrats, new proud owner. :wink:
 
you any idea how heavy a quartz is? i didnt till i tried to carry it up to the first floor of the mill my studio is in ....

kin heavy!!!

but very beautiful :grin: :grin: :grin:

Iain
 
Congrats Iain!
Quartz sounds very nice (jealous :grin: )
But, heck, I have a Megas Mix 30 channel right in my livingroom for remis puposes... needs some serious optical refurbishment but very very nice sounding discrete pre and eq.
I know what you mean (weight) - :razz: They are so heavy because they can be dropped without any serious damage, haha.
Nearly broke my back transporting it a few meters - built like a tank (it even looks a bit like a tank.... :razz:
Dead cheap to get some seriously good sounding desks nowadays.
(I paid 6.66 Euros per input channel including shipping) :guinness: :green: :thumb: )
 
Yeeehaaa!

Got the replacement parts today, bridge rectifiers. De-soldered the old ones and soldered the new rectifiers. Turned it on and voila....no ENORMOUS hum anymore. :wink:

Still I would like to note that REMOVING the original rectifiers is VERY frustrating if you do not know how to remove them. So after trying things, very carefully, I finally managed to find a way.

It was not easy you know. I had to bend the pins and push them onwards the PCB. Then cut a bit in the pin for making the bending easier and I bend it till it broke. After that re-apply solder and carefully match the height of the original ones just in case. After many hours still no hum. I'm just very happy you know. :grin:

There's one more thing to do ; meterbridge lamps replacement. Tomorrow then. And uh.....where is my BEER! :green:
 
Ahhh, yes....
I guess my subconsciousness chose to forget this procedure....
otherwise I might have warned you.
Yes, it was a hell to remove the rectifier.

GREAT you got it going without the hum!
:guinness: :guinness: :guinness:
Now I guess you will like this desk really!
The Topaz definitely has it's own sound...and I really like it as many others do as well. I guess it is much underrated due to chip pre and fader/pot quality of many worn out live boards floating around - but they are great bargain when working ok. :thumb:

Have fun with it,

Martin
 
PS: As Cannikin already noted:
Be careful with opamp upgrading. Especially the topaz will not benefit from simple new opamp plug-in.
mr. Williams does an upgrade that includes a fast LT opamp that some people seem to like, but most stick with the originals after trying opamp upgrades, even in the master section!
Kind regards,
Martin
 
Thanks for your reply. But today it starts to hum AGAIN! :cry:

I'll keep you people updated.
 
Just letting you know the Topaz is fixed now.  :D

Replaced the new parts with some original (LM388K) components and all works well again. Probably got that hum from a loose voltage regulator....

Peace,
Dennis
 

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