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Have a vintage Altec 9440A amplifier and the power capacitors 2 pcs Sprague 9800uF/100v each need to be replaced. How much higher capacitance may the a new capicitor have ? Is 50000 Uf/100V safe ?
Any recommendation of brand ?
Follow Ups:
No, anything over 30,000µF will blow the rectifier.Changing the bridges to fast types will require inrush current limiting to be needed.
Change the input coupling cap, the cap in the feedback loop to ground, add film bypass caps across same, and change the 10µF bypass caps (two per driver board) to 22F/160V.
Unsolder all transistors with gold leads and re-solder with 4% silver, you must wick off all gold-contaminated solder.
The gold pins in the edge connectors must also be wicked and re-soldered.
Clean input jacks and all Molex connectors with Caig DeOxit.
Consider cleaning the relay with same and soldering a 0.1µF film cap across it (before cleaning it, Caig is damaged by soldering heat).
Edits: 06/03/12
Which cap is the input coupling cap ? Value ?
Hi
Have now replaced the 10uF/100V caps on the boards to ELNA Silmic caps, however, forgot to change the values to 22uF.Will 22uF make a big difference ?
Edits: 07/07/12
Hitachi have a 33000uF/100V capacitor that seams to fit i.e a total of 66000uF.
IXYS have a Hexfred bridge 20Amp 600V.
How will the sound be affected by the above changes? Is it woth the extra cost/effort.
What is the 60hz Itsm on that bridge?
If it isn't at least 400A you will need an inrush limiter.
The bigger caps won't sound that much better, the rectifier might make it a bit cleaner. Can't tell you if it's worth it or not.
The 10µF bypass on the cards (that I suggest replacing with 22µ/160V) have more affect on the sound than the main filter caps do, unless you're running at full output. I've never gone above 22,000µF.
The IXYS HexFred VBE17-06N07 has a Ifsm ? of 50A. Any information if an inrush limiter required?
Any information how to check the transistors on the power board?
How long will these last ?
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