New Member with Carver PM-1.5 I would like to fix

[Keyman69 4]

Hello everyone, 

 

I am a retired electronics design engineer who designed mostly digital and embedded microprocessor designs with a smattering of some analog circuits along the way. 

The Carver PM-1.5 is quite the challenge.   I bought it many years ago and it worked well until the large power supply capacitors failed.  I replaced them and it worked for quite a while longer and failed some years ago. I removed the dual power supply caps and found they had failed which is at least part of the problem.  Now I am looking at sourcing replacements for them ( I have seen the EBAY replacement board with 4 caps),  but I will probably make my own. 

 

Then I will see what else is wrong with it if I am able to .  I appreciate any suggestions along the way.  Especially how I can isolate my digital oscilloscope so I can use it to safely view wave-forms should I get that far. 

I have a Variac specially for this,  but have never had the issue of needing to also  isolate a 'scope to make measurements.  Ways to do that would be greatly appreciated and thanks ahead of time if any one out there has the way. 

Edited Saturday at 09:19 PM by Keyman69

[Half Life 1,392]

Welcome from Virginia!  Enjoy your stay!

[Jeff Stone 337]

Welcome to TCS!

[3M_Audio 2,370]

Welcome! When you talk about isolating your scope are you thinking about a high voltage differential probe? I have the Micsig DP10007 and it's worked well for me when I need to measure a voltage difference at two points not at ground potential.

 

[Receiver2000 4,851]

Welcome!!!

[Half Life 1,392]

Agree with @3M_Audio.  You can't go wrong with the Micsig line.  Reliable all day long.  I've read the Hantek HT8050 is also fairly good but is only a 50MHz probe..

[Sk1Bum 13,285]

Hello Keyman69 and welcome to thecarversite.com. Glad you found us!

 

I wish I could help you with your questions, but I am by no stretch of the imagination a tech. I'm more of a magician. I could turn an amp into a brick, door stop, or boat anchor.  

 

Good luck with your repair!

 

[Charlie 19,761]

[AndrewJohn 11,117]

Welcome, @Keyman69, glad you found us.

 

Also, to support your project, be sure to download the service manual.  The Carver PM 1.5 has two incarnations..., the second to address issues in the first version - both are good - but the reading will help identify which you have, and how to proceed. 

 

Check out these two Service Manuals as your proceed.

 

[AndrewJohn 11,117]

@Keyman69, Quoting descriptions from another member Dominic, @zumbini, 

 

How we got to the different versions of the PM-1.5...

 

 "fan failures were common in early PM-1.5s". These amps were recalled and repaired and the revised amp sold as the PM-1.5a / PM-1200."

 

"The PM-1200 and it's predecessor the PM-1.5 are basically an M-1.5 with larger output devices, balanced inputs and fan cooling. Should be no surprise that they sound alike."

 

We love repair threads..., and lots of pictures.   Consider posting yours in the Amp forum! 😉 others may benefit, and yet others, may chime in with help.