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Electronics => Repair => Topic started by: lancelotburt on January 22, 2019, 09:42:58 pm

Title: HP 8662A PS Inverter Board Question
Post by: lancelotburt on January 22, 2019, 09:42:58 pm

I'm going over the power supply boards on my newly arrived HP 8662a SSG and the A7A3 inverter board looks like this.  Any cause for concern regarding the cracked black components?  The really cracked little one is a ferrite choke.  The bigger ones are coil chokes.

Title: Re: HP 8662A PS Inverter Board Question
Post by: KE5FX on January 22, 2019, 10:51:44 pm

I wouldn't be too concerned about the cracked epoxy, but be sure to check the ESR of all electrolytics on that board.  Some of them are highly stressed. 

Also check the screws that hold the various power semiconductors to their heat sinks, very common to find these loosening up over time due to cold flow in the PCB material.  It's a good idea to renew the heat sink compound as well, after cleaning the old stuff thoroughly with alcohol.

Title: Re: HP 8662A PS Inverter Board Question
Post by: lancelotburt on March 10, 2019, 08:50:54 pm

Thanks. 

Did that.  I also ended up replacing the main filter caps, one other electrolytic, and the A3A8 FM SL VCO card, and now it works.  Some calibration and I'm set.