Help Troubleshooting Millenia Media HV-3B PLEASE

[moamps]

Yes.

 

[sonolink]

Find the zenner diodes on the PCB and take off one leg each, then try the preamp. As Ike suggested, try to find a signal source that you will connect to the XLR input as a test signal. It can also be a signal from a sound card, in some software you turn on the generator at about 440Hz (phantom shold me off).

The zener diodes are the orange ones right? (Excuse my ignorance....)

 

[moamps]

find a designation (name), ask google

 

[sonolink]

find a designation (name), ask google

I did
And the pic Google shows is an orange diode. But since this preamp is quite old I just wanted to make sure the grey diodes are not zener, or maybe not all orange diodes are zener...

If the orange ones are zener diodes them there's only 3 on each board

 

[moamps]

silver body with black ring? D3,5,6 ...

 

[sonolink]

Those are the zeners??? Ok. Thanks for pointing that out Moamps!!
I'll cut the silver ones then
Cheers
Sono

 

[Ike Zimbel]

I did
And the pic Google shows is an orange diode. But since this preamp is quite old I just wanted to make sure the grey diodes are not zener, or maybe not all orange diodes are zener...

If the orange ones are zener diodes them there's only 3 on each board

The orange ones are glass diodes, which can be Zeners, or just plain old diodes. The best thing is to try and read the number off them and look up the value. All diodes (that I'm aware of...) will start with 1N followed by a 4 digit number (usually!). So, 1N4148 is a glass, 1/2 watt rated plain old diode, 1N4728A is a 1 watt rated, 3.3v Zener and they can come in glass or plastic bodies. Just to fill you in a bit on diodes...

 

[sonolink]

The orange ones are glass diodes, which can be Zeners, or just plain old diodes. The best thing is to try and read the number off them and look up the value. All diodes (that I'm aware of...) will start with 1N followed by a 4 digit number (usually!). So, 1N4148 is a glass, 1/2 watt rated plain old diode, 1N4728A is a 1 watt rated, 3.3v Zener and they can come in glass or plastic bodies. Just to fill you in a bit on diodes...

Thanks a lot for the information Ike.
Tomorrow I'll try to identify each diode on the board. I can't do it now because I have a soundcheck in an hour.

This thing is getting trickier and trickier but I'm learning quite a bit hehe

Thanks again to all for your help and time.
Cheers
Sono

 

[Cranehazard]

Take out the zener clamping diodes (standard for any repairs at the factory) they really aren't protecting anything if an event happens that can blow the chip it will also destroy the diodes usually plugging in a mic with phantom power engaged with the gain maxed! Then check the 2604s and 5532s usually the transistor array is ok but not always. Match

 

[Cranehazard]

Call Millenia, try to talk to Jay chances are he will walk you through it, warranty or not. They are awesome!

 

[sonolink]

I managed to identify the silver ones but I can't read much on the orange ones. Can someone try to make out anything out of these pics please?

Thanks!
Cheers
Sono

 

[moamps]

You need to remove one leg of D2, 3, 4 and 5. Do not remove the other diodes. These zener diodes are type 1N4742, 12V.

 

[sonolink]

Ok. Thanks Moamps. I'll do that and use a signal with the scope and report back

Thanks for your help!
Cheers
Sono

 

[sonolink]

Ok, so I sent a 1k sinewave into the mic input through a balanced cable from my soundcard after lifting the zener legs.
Readings are:

U3 pin6

 

[sonolink]

U4 pin6

 

[sonolink]

I couldn't find U8 so I assumed you meant U6

Pin8

 

[sonolink]

U6 pin1

 

[sonolink]

What now?

 

[moamps]

I will repeat my post 59:

Check that the pins are connected according to the figure, then that pins 2 and 3 of the XLR are connected to the pcb.



And, find on those XLR pins nice sine wave of 1kHz on your scope. That's the start.

 

[sonolink]

Sorry for the language barrier Moamps.
This is what I did:
-First I checked continuity between the pins indicated on the pic and it checked ok.

Then I checked that the female XLR connector on the chassis was properly connected to the 2 pins indicated on the pic and to ground.

Then I made a TRS-Male XLR cable to connect my soundcard, created a Logic session sending a 1khz sine to the cable.

Then I connected the scope probe on channel 1 and connected and and the probe end to U3-pin6 and after that to U4-pin6.

What am I doing wrong?

Cheers
Sono