Info on this diy Danner cassette rack

[LB82]

Hello everyone,

I got this diy rack for Danner cassette format, I bought it used with 2 BFE eq modules in it.
After a couple of years of use the eqs showed some problems and one of the two stopped working, I sent them to repair and I was told that a lot of transistors and other components inside the modules were damaged and it was a difficult repair.
I'd like to understand if the rack is the cause of those problems, so I know if I could use it in the future with some other modules or send it to repair, The only thing I noticed in use is that when I turned the power off the ">18dbu" led on the eqs blinked like they received a spike of volts while turning off, apart from that the eq worked.
I attach some pictures here of the rack and the power supply if anyone can help me understand, thanks

 

[gyraf]

..here's nothing to explain why it would be "a difficult repair"...perhaps get a second opinion, from someone you trust?

/Jakob E.

 

[LB82]

..here's nothing to explain why it would be "a difficult repair"...perhaps get a second opinion, from someone you trust?

/Jakob E.

Hello, thanks for the answer.
The modules are already been repaired, I was wondering if this rack looks well built and "safe" for using it in the future or not. Unfortunately I don't know any technician in my area

 

[pucho812]

difficult repair? What does that mean exactly? Is it possible they couldn’t find the right transistors or right physical size of capacitors?
At any rate nothing in the photo shows anything that could be a cause for modules to be damaged. It’s a rack with psu and edge connectors wired for I/o and power. If the modules were working for a period and then suddenly stopped, it doesn’t lead to any clue that the rack is the culprit. You would have to get the rack tested to confirm that.
The modules may have reached age where parts hit their failure point such as capacitor failure which may have caused other issues.

 

[LB82]

difficult repair? What does that mean exactly? Is it possible they couldn’t find the right transistors or right physical size of capacitors?
At any rate nothing in the photo shows anything that could be a cause for modules to be damaged. It’s a rack with psu and edge connectors wired for I/o and power. If the modules were working for a period and then suddenly stopped, it doesn’t lead to any clue that the rack is the culprit. You would have to get the rack tested to confirm that.
The modules may have reached age where parts hit their failure point such as capacitor failure which may have caused other issues.

Thanks for the answer.
I was told that one of the cassettes had some bad work done by a previous tech with bad solder everywhere and that the other just needed recapping and calibration, the modules are fine.
My doubt was if the rack was somehow "guilty" of the faults, unfortunately I don't have the skills to test it, the only thing I tried to test with a multimeter is the output voltage of the AC psu which is supposed to be 24 volts but it was not exactly 24 volts, was a bit less, around 21.
I found out that it is a very cheap (10 euros) AC power supply, maybe buying a better quality psu would deliver 24 volts stable?
The "<18 dbu" overload light of the equalizers flashing at the power off of the rack also made worrying that the modules could have some dangerous voltage spike during the shutting down and that on the long run could damage the units.
The guys that repaired my modules make some high quality racks for Danner cassettes with internal psu but I was wondering if this rack would still be useful in the future or if it's better to get rid of it, unfortunatley I cannot understand it bymyself looking at how it is built

 

[pucho812]

On second glance I do see the switch which has exposed parts which could ground out to the chassis, the resistor as well as green wire need to have heat shrink over them. If the guy who fixed them makes a rack mount for them, If you can see about getting one for a demo and see if you like it. Not all power supplies are created equal

 

[LB82]

On second glance I do see the switch which has exposed parts which could ground out to the chassis, the resistor as well as green wire need to have heat shrink over them. If the guy who fixed them makes a rack mount for them, If you can see about getting one for a demo and see if you like it. Not all power supplies are created equal

The guys who fixed the modules make high quality racks with custom internal power supply (toroidal), I'm sure their racks works perfectly. I was wondering if this older rack could still be useful, do you think it would be possible to fix the issues you saw about the switch and the capacitors? Buying a better 24 volt switching psu instead of the Star psu I posted could also help?

 

[TwentyTrees]

Did you notice any excessive noise or hiss when the modules were working ok?

 

[LB82]

Did you notice any excessive noise or hiss when the modules were working ok?

No, very quiet, haven't measured but really good noise floor for musical application. The 24 to 16 bit dither of Fabfilter Pro L2 added a bit higher noise floor than the eqs, to make a comparison

 

[TwentyTrees]

Great, then on the face of it your SMPS would seem to have been working fine at the time. Obviously replace if it's faulty, but I'm not seeing a need to upgrade it.

 

[LB82]

Great, then on the face of it your SMPS would seem to have been working fine at the time. Obviously replace if it's faulty, but I'm not seeing a need to upgrade it.

Thanks.
May I ask you what you think about the "> 18dbu" overload led of the equalizers blinking when the rack is shutting down?
That was my main concern, togheter with the psu outputting around 21 volts instead of 24. I have some devices here that make some sort of loud "pop" sound when you turn them off but since I paid more than 1000 euros for this eqs (summing the purchase + restoration) I am bit worried about damaging them

 

[TwentyTrees]

I'm not familiar with the EQs in question so I can't speak definitely to this. Unless there's any digital logic or similar, I'd imagine that 21V rather than 24V would manifest as slightly lower headroom. Happy to be corrected by those more knowledgeable, of course!

Do you have a schematic for your EQs? That might help shed some light. In the meantime, did the overload LEDs blink every time you turned the unit off? Did that happen when they were working well, or just when you started experiencing issues?

 

[LB82]

I'm not familiar with the EQs in question so I can't speak definitely to this. Unless there's any digital logic or similar, I'd imagine that 21V rather than 24V would manifest as slightly lower headroom. Happy to be corrected by those more knowledgeable, of course!

Do you have a schematic for your EQs? That might help shed some light. In the meantime, did the overload LEDs blink every time you turned the unit off? Did that happen when they were working well, or just when you started experiencing issues?

Unfortunately I don't have the schematics, I found here on Groupdiy the schematics of the Filtek Mk3 which should be identical to the BFE Mk3 that I have but I cannot be sure about it.
The led blinking happened after the repair because before the repair the leds were not working properly, now they are very responsive and quickly blink on and off during momentary overloads.
Before the repair one didn't blink at all and the other once it blinked it stayed lit until bypassing the eq. The eqs sound also generally cleaner after the repair, using the same rack and psu as before.
I have bought a new psu, exactly the same as the Star psu I had before, the one in the pics I attached in the first post. I have to check if the blinking happens also with that new psu

 

[TwentyTrees]

In a thread on the Filtek Mk3, one person notes "The red LED overload indicator will flash briefly (look in a darkened room) when the unit is turned on". If they're identical, that may be relevant here.

 

[LB82]

In a thread on the Filtek Mk3, one person notes "The red LED overload indicator will flash briefly (look in a darkened room) when the unit is turned on". If they're identical, that may be relevant here.

That is really helpful, thank you very much.
I didn't notice any blinking in my rack on power on but only on power off but maybe it happens for the same cause, the switching on/off of the power supply