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I am trying to fix a Guyatone AE-5 I bought as not working. It came with an MN3205 which does not work in the circuit. I am pretty sure it needs an MN3005 and I have got one coming. I just wanted to confirm the correct power connections before I fit it. Looking at the pcb, the 3005 ground pin is connected to the +12V supply. VDD on the 3005 is connected to circuit ground so, if I have understood this correctly, the 3007 VDD pin sees this as -12V.

Is that correct?

Thanks in advance.

Yazoo55 wrote:I am trying to fix a Guyatone AE-5 I bought as not working. It came with an MN3205 which does not work in the circuit. I am pretty sure it needs an MN3005 and I have got one coming. I just wanted to confirm the correct power connections before I fit it. Looking at the pcb, the 3005 ground pin is connected to the +12V supply. VDD on the 3005 is connected to circuit ground so, if I have understood this correctly, the 3007 VDD pin sees this as -12V.

Is that correct?

Thanks in advance.

Hi,
Why don't you google the datasheets for your BBDs?

I've got the datasheet. I'm not very good at this though. I know the MN3005 requires up to -15V on the VDD pin. I checked the schematics for a couple of other effects which use this chip and they are powered in the way I described. I was just hoping for a confirmation from someone more knowledgeable than myself.

Yazoo55 wrote:I've got the datasheet. I'm not very good at this though. I know the MN3005 requires up to -15V on the VDD pin. I checked the schematics for a couple of other effects which use this chip and they are powered in the way I described. I was just hoping for a confirmation from someone more knowledgeable than myself.

Having positive voltage supply (VCC), Pin5 (VDD) on mn3005 is usually grounded, while pin 1(gnd) can be tied to VCC directly (or through limiting resistor) or float between VCC and GND.

You can seach for other mn3005 delays to find quite a bit of them having different implementations.

Good news
It's working. I received the Xvive MN3005 from Banzai today (just short of €30 including postage). My initial thought was "this is going to be an expensive puff of smoke". When I finally fitted it and powered up - nothing.

Then I remembered the DC bias adjustment. It was a fine tune but then it leapt into life.

I am using a bench power supply because the power circuit is incomplete. Someone has fitted a new 12V AC transformer but there is a 3pin component missing. I am going to build a regulated 15V DC supply using an LDO regulator rather than try to recreate the original supply. I think it used a power transistor rather than a linear regulator because the empty 3 pin footprint on the board doesn't match either an LM317 or an LM7815. There aren't any schematics online that I can find to confirm this.