I was trying to button up a Superscope CRS-4000 after a belt change but I'm getting a right channel squeal when I hit cassette play (that changes with the volume). It only squeals in this PLAY condition and the tone also changes with the three position tape type switch. The radio and aux-in play fine. The squeal changes when I touch the main metal chassis to the cassette metal chassis and sometimes it degrades and goes away but there's little volume in the right channel when I can hear music. I'm going to try and clean the switches again, the cassette didn't work when I bought it so I don't know if it was an issue before. Any ideas?
I would start with R ch wiring from the head to preamp section, sounds like a short or dead bypass cap there... Do we have a SM for CRS-400? I was/still considering buying one you suggested off eBay, but my skills of hiding them from The Boss are minimal these days, and she is vigilant!!: have to rebuild our home first!
Maybe I should load up a van full of tools and a few boxes and head your way Jorge for a few weeks of R&R building a house! I only require loud music and cold beverages at the end of the day. So I went out tonight and the squeal was gone but there was still no music and now I had static in the right channel (with regular volume music in the left), I tugged on the wires coming off of the head, worked all of the switches, didn't really do much and I was now getting no sound. I accidently had the PHONO switch on and I hit the TAPE switch, all of a sudden both channels came to life. For about three minutes I had perfect sound. I made the mistake of swapping out my test tape and put in something good, I must have reactivated the issue and the squeal came back. I'm leaning towards a bad ground, shorting wire or I still may have a bad switch, maybe the PHONO isn't turning off. These have separate buttons for TAPE/PHONO/AUX and not one multi-switch. Tomorrow I think I'll try hooking everything up and seeing what happens, hopefully it isn't a cap, I have a bad habit of wanting to fix everything if I go in. These are great units Jorge, the inside build is amazing, it's almost art the way some of the connections are done. It's not a difficult box to work on but there are a million screws and some of the wiring harness are short.
Ha! from the perspective of the house itself, this might be its only chance And Yes, I can guess what you are talking about. When I fixed a granddaddy of bboxes, Superscope CRS-152, it was a real pleasure knowing that the original build is for ages! I almost bought 4000, and being soo cheap its not a huge financial hit. But I am running out of hiding places for bboxes . Also it has a broken antenna, the worst 'unobtanium' glitch in bboxes, that keeps my finger off the BUY button! Keep all heavy wrenches away from CRS-4000!!!! When I fixed my (now workhorse) Panasonic RX-5500 I got so mad at myself that hardwired/shorted ALL the switches, knobs, and that famous REC sliding bar!! Only then I could finally determine that the culprit for the L ch. was MPX Filter. Desoldered those buggers (I am not going to record anything off the radio: never did and its too late to start now) and all went back to normal... until a few weeks ago when pressing PAUSE button a few times is a must before Play, otherwise the same L.ch. gets noisy
I did a little more last night and may have fixed it, I pulled the cassette transport out again and carefully reassembled everything. It's working fine now but I can't get it to squeal at all, I think it may have been a dirty switch, I'm leaning towards the PHONO button. I worked all of the controls pretty hard to get them clean. I used CRC Automotive Contact Cleaner and it may have some different properties than DeOxit and may have taken longer to clean. I was looking at one of the wires screwed to the chassis, I'm thinking this is a ground? It had some crust and blackening, more than the other screws, maybe there's some corrosion and the ground isn't making good contact, maybe you have a similar issue? I also had a wire on a Ford Truck that looked great even though it was from 86, I cleaned all dirt and corrosion off of it but I still had an intermittent stalling issue. It took me forever to find, but where the wire itself was pinched on the ring connector (under plastic protection), had become highly corroded and wasn't making great contact with the connector.
Good point, maybe it is a vibration from pressing PAUSE which fixes the grudge, Thanks!! When I free enough desk space to open a bbox I will check what is going on there, maybe Pause is connected to some leaf-switch or muting module?
I stay away from the PAUSE button, I think I heard it back in the 80's and it might be folklore, but their trouble unless your cueing a brand new tape. I've always had drop-0uts, weird noise, etc on tapes I've paused.
I press Pause a few times before playing a tape: feels like some switch got oxidized. But it makes total sense not to overuse Pause button during Play, when it lifts the pinchroller there is a split-second when tape is still pressed to capstan but not strong enough to pull the tape; between pull-up reel and rotating capstan anything can happen to the ferrite layer then. Even more variables during Rec, but since I am not a big fan of mixtapes or singles, this was never a problem for me
I pulled it all back apart, got the squeal back and slowly put the transport in a screw at a time. I think there might have been some shorting of the wires coming off of the head where they wrap around the back side of the main board and are wire-wrapped to the main board. I might have pulled them causing a short between the posts. I made sure nothing was touching and it works great now! I posted the beauty in the beer and boomers thread. Thanks for the help Jorge, it's nice to check out all the potential issues.
