Carver AV-705x

[FredR]

Not designed by Bob Carver, but interesting. Did a number of upgrades to this. New panel mounted RCA jacks. Original PCB mounted jacks tend to fail when used with high end very tight RCA cables. All 5 on this amp were destroyed. Replaced all 5 relays, one on each amp board. Strange white deposits under each. Upgraded from a 25 amp bridge rectifier to 35 amp. Replaced 4 ceramic snubber capacitors. Doubled the capacitance of the bulk supply caps. Added 12 volt trigger relays. Fun project.

 

[FredR]

Oh, and painted the xformer case. It was nasty.

 

[FredR]

Any idea what this deposit on the PCB is? Under the relay.

 

[laatsch55]

White stuff????

 

[laatsch55]

How much wattage in the cottage there Fred??

 

[NavLinear]

That looks like crystalline growth and could be caused by a number of factors - a common one would be residue from the cleaning process.

 

[Gepetto]

Any idea what this deposit on the PCB is? Under the relay.

Yes
Wash residue from the original board cleaning process. Large flat areas like that relay trap the liquid used for cleaning underneath them during the board washing process. Later the water or solvent evaporates leaving the flux residue that was trapped in the solvent. Can lead to dendrite growth if this was an aqueous flux solder process. The flux in aqueous is conductive.

 

[FredR]

Thanks guys. Review of the AV-705x:

http://thecarversite.com/yetanotherforum/userfiles/Carver AV-705x review.pdf