Fixing Behringer DEQ 2496 "flashing screen" and similar

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#23
Any good cap there will fo the job. For SMPS in my opinion Nichicon are best, but there are some minor trades that also perform well: Jamicon as example.
If you have 3.3V (rare), don't use 50V. The cap so exagerated don't perform good. Use the highest immediate to the voltage found. 3.3DCV sounds rare for a self power of the PWM chip, usually are in the 12/15DCV as they have to drive the main MOSFET gate, and 3.3V is too little. 16V seems reasonable.
 
#26
For solder, I'm considering 217C melt point Kester 0.31 with 48 activated flux. Flux is said to be not good for "sensitive electronics" but probably better for an amateur like me. My old standby was a 63/37 Kester with activated flux. I see lead free solder melt points go all the way up to 800F. This is a lower one, but still higher than leaded solder. https://www.amazon.com/KESTER-SOLDER-24-7068-1402-SOLDERWIRE-217°C/dp/B00DDDFYKW?th=1 An alternative would be identical except 275 "clean" flux like this https://www.amazon.com/Kester443-84...sprefix=lead+free+solder,aps,117&sr=8-11&th=1
 
#30
charlesp210 said:
I have 7 Behringer DEQ 2496 units in continuous usage in 3 different systems. They conveniently allow me to do a wide range of adjustments I need to do, including parametric EQ, graphic EQ, bass limiting, level adjusting, level monitoring, and RTA. And all with midi controllable setting memories. They are useful in multiway as well as (my kind of) multichannel systems.

Around 2013 I discovered I could even use them to replace the Behringer DCX crossovers I was then using. By aligning two "low pass" filters in the parametric section, you can get an LR24 lowpass response, and likewise for the highpass response. This enabled me to use full digital I/O because the DEQ have full digital I/O whereas the DCX only has digital input. Then I can use the DAC's of my choice (so long as DAC latency is corrected for each way and each supported sampling rate...).

I started with one unit in 2005, added the second one in 2008, and on and on. But by 2010 the first one failed, and for me they seem to have lasted 5-10+ years (some of the latest new ones I bought are still going fine, and I've improved the ventilation with higher spacers, and they seem to have improved the parts quality a bit since 2005).

I never fixed any, I just bought new ones like candy as the old ones failed. I saved them in a big pile for "later when I have time to fix them."

I think the time has come to start trying to fix them. They are unavailable new and the used ones (I have sadly learned) may be nearly "used up" if they work at all. I got exactly one year's use out of the last one I bought on ebay for $200.

The latest one (a year after purchase on ebay) has now died with the "flashing screen" problem. When the unit boots up you never get the copyright screen or anything just a flashing screen. Something like half of the ones in my dead pile died with that problem. Others may have the "blank but lit screen" problem, or the "dead as a doornail" problem. I suspect most or all of these problems are power supply related.

Sadly there is no schematic and no service manual. I have found a multipage schematic of some kind but I haven't seen the power supply on it.

I am going to be taking one apart today or soon to see what I can figure out.
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I would reseated the ram chip. Thats what worked for me in one occasion.
 
#32
For the 1000uF, 25V I bought Panasonic, Rubycon, and Nichicon in 5000 hr rated parts. I'm also going to judge by looking at them but only the Nichicon has AQ certification, so I think I may go with that. It means good for inside cars. I also bought the Kester 217C lead free solder with 48 activated flux. I'm going to do some test soldering with it first, see what setting works for it on my Hakko.
 
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