Quantec QRS input meters

[frenkonio]

Hi guys, I didn't find anything related so I need to start a new topic. Anyone here familiar with the Quantec QRS? I recently found one in very good conditions, it works but I 've noticed that the input meters (L & R) even with anything attached to them show some signs of life (I would say from -72 to -36 on the meters).
I've spoken with some people having the QRS and they all told me they got similar symptoms. Another guy told me that cleaning the connectors made the situation better.
Anyone have experiences about this issue?
Thanks!

 

[radardoug]

Is the output clean? Then dont worry about it.

 

[jensenmann]

I used to own a QRS a decade ago. It was very unreliable and funny things were going on. After a PSU modification and recapping everything was fine.

 

[living sounds]

Mine doesn't do that.

I bought it from a dealer who had the PSU rebuilt, but within 30 minutes it failed and had to be sent to a specialist (former Quantec technician) for repair.

I got it back fully working, but even then it is not free of different kinds of noise. It is a very quirky design, similar to the AMS dmx15-80S. Lot's of cards, connectors and old components no longer working fully in spec. But like the AMS it sounds gorgeous.

 

[frenkonio]

Is the output clean? Then dont worry about it.

Yes, the output is "clean" even if this machine has a very bad noisefloor (and it was a known issue). But I would understand why it does that on the meters and possibly find the solution. I didn't recap anything, it still is in his original state (still Frako caps on the psu but they work).

 

[frenkonio]

I bought it from a dealer who had the PSU rebuilt, but within 30 minutes it failed and had to be sent to a specialist (former Quantec technician) for repair.

How many years ago it was done? Who's the specialist?

I got it back fully working, but even then it is not free of different kinds of noise.

Mine too, sometimes, but it happens really randomly and only a few times makes some quirk digital burst of a second or so. Yours too?

 

[living sounds]

How many years ago it was done? Who's the specialist?
Mine too, sometimes, but it happens really randomly and only a few times makes some quirk digital burst of a second or so. Yours too?

This year. The specialist ist in Germany/Switzerland. I can PM you a contact if you like. If you are in the US there are specialists, too.

If you want to try fixing it yourself I have the schematics.

Mine has low level hum, digital noise and a 20k sine spike. No sudden bursts. But looking at the datasheet that states dynamic range of 85dB it is probably in spec and as good as it actually gets.

 

[frenkonio]

This year. The specialist ist in Germany/Switzerland. I can PM you a contact if you like. If you are in the US there are specialists, too.

If you want to try fixing it yourself I have the schematics.

Mine has low level hum, digital noise and a 20k sine spike. No sudden bursts. But looking at the datasheet that states dynamic range of 85dB it is probably in spec and as good as it actually gets.

I am located in EU. I think I will do a recap of the psu and clean up the contacts from the boards to the main motherboard attached to the psu one.
The burst seems strictly related to the dram board, I think I will order some nos and swap them too as they are socketed.
Send me a PM, thanks so much.

 

[BrianJSiegel]

This year. The specialist ist in Germany/Switzerland. I can PM you a contact if you like. If you are in the US there are specialists, too.

If you want to try fixing it yourself I have the schematics.

Mine has low level hum, digital noise and a 20k sine spike. No sudden bursts. But looking at the datasheet that states dynamic range of 85dB it is probably in spec and as good as it actually gets.

I have been looking everywhere for the schematics with no luck. How do I get a copy?
-Brian

 

[user 41968]

FWIW and for future reference I have one NOS PIC625 transistor used in the switcher if anyone needs one.

 

[radardoug]

The connectors in the power supply cause problems, I think it is 7 pin?? Molex. Replace this with heavy wire links. Many problems will go away.

 

[living sounds]

I have been looking everywhere for the schematics with no luck. How do I get a copy?
-Brian

http://www.florian-anwander.de/quantec_qrs/

 

[jensenmann]

What a great resource, thanks a lot!

 

[living sounds]

Just found this website with the contents of the QRS eproms:

https://dbwbp.com/index.php/9-misc/37-synth-eprom-dumps

 

[BrianJSiegel]

http://www.florian-anwander.de/quantec_qrs/

Wow, what a badass....thank you kind ser. That was exactly awesome. Bless you