| Author | Message | ||
| David Pokotylo (davidp) Username: davidp Registered: 01-2009 |
New member here! I recently got a 1982 RD65-112 and am now ordering caps to redo the electroltyics. Right now, there's significant bias creep and it takes around 1 1/2 hrs for the bias level to stabilize enough so I can set the trim pot to the factory level. Can anyone assist in troubleshooting this? I expect the bias cap(s) is the first item to replace but I have difficulty determining which ones these are in this model. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
C31, c33, c40 and even to some extent, c41 can all affect bias. The 150mf@50v and the 20mf are the most likely suspects though. I looked at both driver boards and they appear to have the same bias schem. REPLACE ALL THE ELECTROLYTICS. That amp is old and they will benefit from it. | ||
| David Pokotylo (davidp) Username: davidp Registered: 01-2009 |
Thanks Mike! Just placed an order with Mouser for a bunch of stuff but the single 150mf@3v cap--I've never encountered such a low voltage value and the lowest that Mouser stocks in 6.3v (but I'd have to buy a couple hundred)!! What does this cap do?? | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Well, for some reason, the site's not letting me access the schems so I can't look to see but I would have to guess that it's a filter for the IC''s with that low of voltage. That's just a guess since I can't look. You can go up as high as you want on the voltage rating, just don't change the capacitance much and you'll be fine. Find something like a 150@50 and that should be pretty common. |
Tue, 03/25/2014 - 09:32
#1