David_NC
Super Member
Hi,
I'd like to make this receiver 'safe' and relaible to use and bring its performance back to where it was when new. Cosmetically, it's probably a 9-9.5, and it's fairly attractive design anyway, so it seems worthy of the effort. I replaced all the bulbs about 10 years ago when I was using it. A few days ago, I cleaned the volume pot and pushbuttons (and set the idle current). When connected to my test speakers, it sounded horrible. On a whim, I connected an RCA cable to the pre-main loop and tried again. It sounded much better, which tells me the contacts inside the main-in jacks that short to pre-outs are the issue. I tried cleaning them multiple times with liquid DeOxit and small brushes, but that didn't help. I'm curious if it'd just be better and easier to cut out the internal jumper and make up some external jumpers or if this issue is easily remedied.
When I first got it, it ran really hot, so I adjusted the idle current to the 8mVs as described in the manual. I checked this again recently, and the left channel was right on that; the right channel was high again and is a pain to adjust. It would swing from 2mV to 28mV to 17mV, etc. It took about 15 minutes for me to get it close, and the best I could do was around 7.7mV. Does this indicate an issue with a trim pot or something else? DC offset was a couple mV in one channel, and the voltage regulator measured 34.9V compared to the spec'ed 35V.
This 2235B had a bunch of sticky switches that all function fine now, except for the power switch. I've cleaned it several times, and it still sticks when turning off the receiver. How do others resolve that?
Once I temporarily resolved the pre-main issue, I did some listening last night. It sounded pretty good... powerful and enjoyable. I then swapped it my recently recapped 1060. I replaced the main and filter caps and all the ones on the power supply board recently, though it sounded really nice prior to that. It's not a fair comparison - a recapped 1060 vs an original 2235B - but the 1060 has always sounded better (even before I worked on it) despite being older. The 2235B feels more powerful, but the 1060 sounds way nicer - smoother and fuller and more pleasant, if that makes sense. I'm curious if others have had that same experience with these models or if the receiver will outshine the 1060 when serviced. One thing I thought was a bit odd is that the bottom of the chassis has 2238 printed on it in multiple places. I thought there was a year or two difference between the two models, but maybe chassis for the 2238 were produced while the 2235B was current.
I'd like to make this receiver 'safe' and relaible to use and bring its performance back to where it was when new. Cosmetically, it's probably a 9-9.5, and it's fairly attractive design anyway, so it seems worthy of the effort. I replaced all the bulbs about 10 years ago when I was using it. A few days ago, I cleaned the volume pot and pushbuttons (and set the idle current). When connected to my test speakers, it sounded horrible. On a whim, I connected an RCA cable to the pre-main loop and tried again. It sounded much better, which tells me the contacts inside the main-in jacks that short to pre-outs are the issue. I tried cleaning them multiple times with liquid DeOxit and small brushes, but that didn't help. I'm curious if it'd just be better and easier to cut out the internal jumper and make up some external jumpers or if this issue is easily remedied.
When I first got it, it ran really hot, so I adjusted the idle current to the 8mVs as described in the manual. I checked this again recently, and the left channel was right on that; the right channel was high again and is a pain to adjust. It would swing from 2mV to 28mV to 17mV, etc. It took about 15 minutes for me to get it close, and the best I could do was around 7.7mV. Does this indicate an issue with a trim pot or something else? DC offset was a couple mV in one channel, and the voltage regulator measured 34.9V compared to the spec'ed 35V.
This 2235B had a bunch of sticky switches that all function fine now, except for the power switch. I've cleaned it several times, and it still sticks when turning off the receiver. How do others resolve that?
Once I temporarily resolved the pre-main issue, I did some listening last night. It sounded pretty good... powerful and enjoyable. I then swapped it my recently recapped 1060. I replaced the main and filter caps and all the ones on the power supply board recently, though it sounded really nice prior to that. It's not a fair comparison - a recapped 1060 vs an original 2235B - but the 1060 has always sounded better (even before I worked on it) despite being older. The 2235B feels more powerful, but the 1060 sounds way nicer - smoother and fuller and more pleasant, if that makes sense. I'm curious if others have had that same experience with these models or if the receiver will outshine the 1060 when serviced. One thing I thought was a bit odd is that the bottom of the chassis has 2238 printed on it in multiple places. I thought there was a year or two difference between the two models, but maybe chassis for the 2238 were produced while the 2235B was current.
,25 turn Bourns.
