Help me with this UCD 180 OEM

[Gluca]

Reposting here as this seems to be a more appropriate forum

Hey all

I am building an amp using UCD180 OEM modules and feeding the unbuffered input, everything fine with the PSU and it works for a few seconds and mutes shortly after I turn it on. While I was troubleshooting it, I noticed that it plays for a few seconds every time after I connect pin 34 to low and then it just mutes until I disconnect pin 34 and reconnect it to low.

Any hint?

 

[sumotan]

Is pin 34 connected to pin 5,6,7 or 8 ? Connection to any of this pin
Should allow the put down to take place . I also completed my Oem
With help from members here not too long ago. Btw what front end
Are you using. ?

 

[Gluca]

It is connected to low (namely pin 9-10-11-12). It will be driven by my ECC88 preamp

 

[sumotan]

Wrong Gluca
9,10,11,12 is the neg power line . 34 should be connected to only 5,6,7,8

Ciao

 

[Gluca]

OK. I will rewire it.

 

[Gluca]

nope. one channel starts when pin 34 is triggered to negative power supply and mutes after few seconds and restarts if I disconnect and reconnect pin 34 to negative.
the other channel stays mute regardless of pin 34 status (to ground or negative power supply).

meeehhhh!

 

[sumotan]

Dont understand both modules pin 34 should be connected only to ground

 

[sumotan]

I worry that u might have damage the module by connecting to negative rails

 

[Gluca]

I first connected pin34 to ground but it stayed mute. I tried negative rail after I checked all the connections to find false contact or wrong wiring and they were all OK as per data sheet.

This puzzles me.

 

[sumotan]

Pin 34 is default on stand by mode. To pull down to activate amp it must be connected to ground pin which is either 5,6,7 or 8 pin of the module. It cannot be connected to anything
Else. I presume that you are using single power supply to power both modules. Use a dvm to check voltage of the supply when connected to module on positive n negative rail & see whats the reading

 

[Gluca]

+45 and -45 at the board pins, supplies are shared (nothing fancy, just a bridge+cap)

 

[sumotan]

Did u measure the voltage with modules attached n power up ?

 

[Gluca]

yes, measured at board's pins

 

[sumotan]

it sounds ok. Again I fear that you might have damage the board by connecting pin 34 to neg supply rails in the early stage. perhaps someone can chime in to advice.

Good luck

 

[Gluca]

that would sound strange to me ... it was mute when pin 34 was connected to ground, I connected to low supply only to give it a try as it was not working and all other pins were OK (signal, output, powers). I will shoot an email to Hypex too.

 

[sumotan]

faulty modules perhaps but then again cant be 2 at the same time. your ground connection is it connected directly onto pins 5,6,7,8 or connected to ground of power supply board ?

 

[Gluca]

tried both ... no difference.

 

[sumotan]

Well I'm at lost. Sorry this may sound silly but have you identified pin 34 correctly ?
Also are you using pin 27 & 31 for input ? If so 31 is signal input 27 is connected to
ground

 

[Gluca]

no worries ... I am lost too and checked pins hundreds of times. all look in order.

 

[sumotan]

So are the signal input pins assign correctly ?