50uF cap job

martin g · Post by **martin g** » Thu Apr 21, 2005 5:39 am

Hello I've got a question about 50u an 40u cap job. How could I know when my 50uF and 40uF should be replace? I've got marshall super lead from 68/69 with 4* (2*50uF) and 2 (2* 40uF) chemicon caps.
Thanks

Flames1950 · Post by **Flames1950** » Thu Apr 21, 2005 8:39 am

Visually if you start to see "blisters" or bubbled areas on the ends of the caps they're going soon. Also be on the lookout for white chemical deposits, if they're REALLY going fast.
They can look good and still be going bad though. Listen for signs of caps going bad such as a background hum that will get worse over time as the caps don't smooth the DC properly, or excessive ghost noting that gets worse over time as well.
If you're really not sure, have them replaced but make sure you get the original caps back; having the original parts helps preserve the vintage value of the amp (strangely it can help the value of the amp even if the parts are bad in many cases!!)

martin g · Post by **martin g** » Thu Apr 21, 2005 9:15 am

Hi Tahnks. What do you think about 2*50uF JJ electronics or F&T caps? I've foud that there are 2- 40uF on anode V1 and the last on right side. Schematic said that all 50uF

Flames1950 · Post by **Flames1950** » Thu Apr 21, 2005 10:45 am

JJ's are OK, F&T are preferred but a little more money. 50uF/50uF cans are fine; never seen one with the 40uF's yours has and like you say, all the schematics show 50uF cap cans.