tag:blogger.com,1999:blog-1942841446523709093.post575740274845763642..comments2024-03-26T16:39:26.814-05:00Comments on Oleg's Vintage Audio: Realistic STA-180 Receiver RestorationOleg's Vintage Audiohttp://www.blogger.com/profile/11218870977701943823noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-1942841446523709093.post-29304433322238833232023-10-16T14:02:32.644-05:002023-10-16T14:02:32.644-05:00I would test all transistors installed on two main...I would test all transistors installed on two main amplifier boards. I serviced another STA-180 recently and one PNP transistor (TR01, 2SA565) was weak. I would preventatively replace all 2SA565 and 2SC984 transistors installed on this board: TR01, TR06, and TR07. Also, the pre-amplifier board has a bunch of prone-to-failure 2SC458 transistors which must be replaced as well. And, of course, make sure that all controls are properly cleaned and lubricated.Oleg's Vintage Audiohttps://www.blogger.com/profile/11218870977701943823noreply@blogger.comtag:blogger.com,1999:blog-1942841446523709093.post-50948850747818593672023-10-15T09:27:42.337-05:002023-10-15T09:27:42.337-05:00I have the realistic STA-180. The left channel was...I have the realistic STA-180. The left channel was distorted and then went out. I replaced the four power capacitors in the back. The left channel came back, but it is still fuzzy. Any recommendations?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1942841446523709093.post-19697473868836286192022-10-26T23:06:01.336-05:002022-10-26T23:06:01.336-05:00Yes, you are correct. The Realistic STA-180 is a c...Yes, you are correct. The Realistic STA-180 is a capacitor-coupled amplifier. I tested the filter cap (2200uf/90V) and two coupling caps (2200uF/50V) with an Atlas ESR70 capacitance meter. The measured capacitance on all three caps is still within the factory tolerance spec. The measured ESR of each cap is almost zero. So, I didn't replace them. I rarely change large filter (or coupling) capacitors in vintage gears unless they are faulty. Based on my experience, the large caps usually hold the capacitance very well and have almost zero ESR even in 40+ years old gears. They are not aging as quickly as low capacitance e-caps.Oleg's Vintage Audiohttps://www.blogger.com/profile/11218870977701943823noreply@blogger.comtag:blogger.com,1999:blog-1942841446523709093.post-6356870871976382892022-10-26T20:25:01.447-05:002022-10-26T20:25:01.447-05:00This looks like it's a cap coupled amp, did yo...This looks like it's a cap coupled amp, did you test the two 2200uf caps? And the big power supply cap? It looks like you didn't replace those?<br /><br />It's an interesting receiver. I enjoy reading your adventures, thanks for writing these up!Anonymousnoreply@blogger.com