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Switched Mode Power Supplies (SMPS)

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A

alkasar

Member
Joined 2009
Cristi said:
if you can't find-it or is expensive, just let me know and i will send you without charge by letter.
Click to expand...
Hello Cristi, i replaced the thermistor and it works :) The hardest part was to unsolder the old one! Excellent diagnosis.

I did not pick the thermistor from above links as the shipment charges are outrageously high. I picked the biggest available from a local vendor. He was not able to tell me how much amperage it would support. As it is 9,5mm diameter, larger than old one, it was worth a try.
It worked immediately : +/-27V output again. I connected to the amp (TDA8920BTH stereo, 8ohms speakers) and it works perfectly for an hour at low to medium volume.

Let's push volume up at 75%. After a minute or two ... sound started to scratch :confused: hum... smoke coming from the thermistor area :redhot: I shut amp down immediately . After few minutes, when temperature was down, i switched back on, and it works again. Will not push the volume though!

I take your offer to send me a 10R thermistor that really supports the load. There is actually room to put a bigger one, up to 16mm if required.
Thanks again for your -post sales- support.
 
C

Cristi

Banned
Joined 2008
connexelectronic.com
It is not exaclty a short, there is a jumper between main output GND and aux. GND. in case they share the same GND. if you remove this jumper the aux will be isolated from main output. the jumper have a ferrite bead for HF noise rejection and is between one of the 6800uF caps and one of the 1000uF cap. the designator is R19. simply remove the jumper and the aux GND will be isolated.
 
C

chris7916

Member
Joined 2005
Cristi said:
The actual version of A1000SMPS can provide both differential voltages in range of +-45 to +-58V, different values on request, as well as single voltage in range of +45V to +60V, other values on request.
Aso, a higher power SMPS is under development, but, as we know, it will be available for sale just when will be completed, fully tested and first batch on stock.
Click to expand...

Do you mean one can have both (+-45V) AND +50V at same time? How much power can you draw from the +50V, assuming it's used "alone" (I'm asking because this could be an option for DA-1 amp)
 
C

Cristi

Banned
Joined 2008
connexelectronic.com
The A1000SMPS has by default differential output voltage, but if needed, single voltage can get as well instead of differential voltage. since the transformer can provide 2x50V, by rectifying full-wave the output voltage and has centre tap, a single voltage can also get very easy. if the voltage is in range of 80-120V DC, can use the acctual transformer and the voltage will get between -V and +V ouptuts, and if the output voltage needed is lower, between 40 to 60V the output voltage will get between +V and GND, but a small modification need to be made, the negative reference for the error amplifier must be moved to GND instead -V as it is by default. i can make this modification on request.

Anyway, since i have few more requests, i will make a single main output voltage plus an aux. voltage smps with output power between 500W and 1000W. that one will be suitable for DA-1 amplifiers.
 
F

fb

Member
Joined 2005
SMPS250 should be big enough – it’s for 2 TC2000/STA508 modules into 8 ohm drivers. I don’t need another AUX voltage, as I can get one off the SMPS500R for my BIPS modules.

Also, is the SMPS500R ok for a TA3020v3b with IRFP4228: +-60V into stereo 8ohm? I’m a bit concerned about the voltage drop you mentioned in another thread: “the A500SMPS use half-bridge resonant topology, the output voltage is not regulated and drop about 10% at maximum power. this is the classic topology used in >80% of the PA amplifiers.” It won’t be run with sine waves or anything, just music.

Thanks
 
C

Cristi

Banned
Joined 2008
connexelectronic.com
As fb pointed put, the SMPS250 works fine for TA2022 amplfier. in fact, the amplifier has connections for +V and -V, so the smps can be connected directly there, skipping the rectifier bridge.
the A500SMPS has no-regulated outputs, but the SMPS500R, has regulated output voltage, which does not drop when the current draw increase. it uses LLC resonant topology, with efficiency over 90%.
 
A

alkasar

Member
Joined 2009
dubai2000 said:
Mhhh....a pic says more than a thousand words....:). I don't know how to insert it here, but perhaps you can provide me with an email address off the forum - thx.
Click to expand...
visually : look at page 4 of the TA2022 webpage pdf manual.
Top right of the pcb you see -Vcc and +Vcc holes.

You can also look at post #11 of this thread. It has a schematic on how to plug smps with TA2022.
 
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