Fixing Mark Levinson 300 series start issues

[willcycle]

I would just like to pass along some information on fixing start up issues on Mark Levinson 300 series amplifiers not due to output stage malfunction. Levinson has an engineering change order to address this issue by replacing IC U1 on the voltage gain board with LT1097CN8 opamp. It fixed a problem I was having with a 331 starting then turning off.

 

[DanPe]

Hi willcycle,

Can you be more specific about the problem that you encountered?

I just bought a ML 331 and I'm going through all the ECO's that I found in the Service Manual and the replacement with LT1097CN8 is one of them.

Also, the ECO's mention part numbers for the replacement components but I cannot find these part numbers. This is needed to have the correct specs of these components. Can you help?

Greetings,

Daniel

 

[willcycle]

When coming out of standby after pressing the power button the amp would immediately shut off. The IC part number is the actual number.

 

[DanPe]

Hi Willcycle,

Thanks for your reply. Indeed IC number is clearly mentioned in the Service Manual but it also suggest to replace the Sprague 68 µF 25 VDC capacitors (6 pieces) by part number (240-200013) but nowhere I can find more info of what is behind that part number.

Greetings,

Daniel

 

[rsavas]

We do not have much to work with, no schematic, no pics of the part in question, so hard to give advise.

 

[willcycle]

I replaced those 68 uF caps with equivalent Nichicon parts. I wouldn't be too concerned about a specific part here. Use 105 degree caps.

 

[DanPe]

Hello Willcycle & rsavas,

Thanks for your replies.
I add some more details: see the attachments.

Those Sprague 68 µF 25 VDC are still available but they cost around 15 € each. I'm just wondering why ML used 'special' caps for this and if I can replace them by just standard caps.

Greetings,

Daniël