Hello C-100 owners. I came across a curious glitch while working on the "Tape 2" upper auto-reverse cassette deck on my Clairtone 7980(A.K.A. C-100). I replaced the motor with a motor I salvaged from a defunct Crown 5100 which fit perfectly, btw. I used the ferrite ring from the old motor & modded it slightly to fit around the replacement. This reduced the magnetic hum of the new motor affecting the playback head. I adjusted the speed by ear & adjusted the azimuth of the head(tracking) until both directions played well with great dynamic range & stereo imaging, by ear. Once I got it all together, I did some listening tests to make sure I got it all right.
Well, after a few songs, changing directions of play, using the program selector button(far right button on deck 2), the head would come out of alignment & the forward(>) direction would start to sound more & more muddy. If I play a cassette in the reverse(<) direction, it would sound somewhat better but still you can tell it was coming out of alignment too since both directions use the same head. Eventually, the treble & mids would be almost completely gone from the music on a good Maxell chrome cassette in both directions. Bummer!!
So, not to throw in the towel I ordered a set of screwdrivers from the UK which included a very hard to find 15" long Philips #0 so I could pop the back off the blaster & insert the screwdriver through the adjustment holes of the various circuit boards above the tape deck & adjust the head azimuth(tracking) while a tape is playing. Before buying this special screwdriver, I had to actually remove the chassis from the cabinet, remove the upper deck from the chassis & adjust the set screw for the head while it was powered, using headphones to guide me by ear.
What a pain in the woofers to find out all that grief was for nothing after just a few songs when the head would drift out of alignment again. ARRGGGG!!!
Well, again I went searching for answers & found a few references regarding using nail polish on the set screw to keep it in its adjusted position after alignment & decided to give this a try. I popped off the back of the 7980, used my super long Philips #0 screwdriver to adjust the heads again & then brushed a generous dab of clear coat nail polish on the side of the set screw after adjustment. I let the clear coat dry overnight before testing out the results & I think it worked keeping the set screw in place & preventing the head from coming back out of alignment. I've been doing listening tests in both directions for a couple of hours now & it seems to be holding up quite well.
The reason for using nail polish is that it is an easily breakable seal of sorts which allows for further adjustment in the future. A glue or epoxy would be too aggressive for this application. I've listened to a few C-100s & AKAs over the last year or 2 & have always noticed the 'Tape 2' playing better in the reverse direction(<) & sounding quite muddy in the forward direction(>), every time. This was true for units that were 'professionally' serviced & I was always amazed at how terrible the sound was after such service.
Here is a video of the results after using my super long screwdriver & nail polish trick. I recorded music on a Maxell Normal(Type I) cassette for this demo, using a Denon 3-head deck with Dolby 'B' HXPRO. Feel free to comment any insights or thoughts about it.
My questions to other members here is:
1. Have anyone else who owns a C-100 or AKA, noticed the same phenomenon regarding muddy playback in the forward direction & sounding better but not great in the reverse direction?
2. After working on deck 2, has anyone else noticed the azimuth(alignment) of the head coming out of whack after a few songs of play on their Conions or AKAs?
3. Has anyone else used nail polish to secure the set screws after adjustments & if so, how well did it work for them?
I am keen to hear from others about this & how common or uncommon this problem is for them...
Well, after a few songs, changing directions of play, using the program selector button(far right button on deck 2), the head would come out of alignment & the forward(>) direction would start to sound more & more muddy. If I play a cassette in the reverse(<) direction, it would sound somewhat better but still you can tell it was coming out of alignment too since both directions use the same head. Eventually, the treble & mids would be almost completely gone from the music on a good Maxell chrome cassette in both directions. Bummer!!
So, not to throw in the towel I ordered a set of screwdrivers from the UK which included a very hard to find 15" long Philips #0 so I could pop the back off the blaster & insert the screwdriver through the adjustment holes of the various circuit boards above the tape deck & adjust the head azimuth(tracking) while a tape is playing. Before buying this special screwdriver, I had to actually remove the chassis from the cabinet, remove the upper deck from the chassis & adjust the set screw for the head while it was powered, using headphones to guide me by ear.
What a pain in the woofers to find out all that grief was for nothing after just a few songs when the head would drift out of alignment again. ARRGGGG!!!
Well, again I went searching for answers & found a few references regarding using nail polish on the set screw to keep it in its adjusted position after alignment & decided to give this a try. I popped off the back of the 7980, used my super long Philips #0 screwdriver to adjust the heads again & then brushed a generous dab of clear coat nail polish on the side of the set screw after adjustment. I let the clear coat dry overnight before testing out the results & I think it worked keeping the set screw in place & preventing the head from coming back out of alignment. I've been doing listening tests in both directions for a couple of hours now & it seems to be holding up quite well.
The reason for using nail polish is that it is an easily breakable seal of sorts which allows for further adjustment in the future. A glue or epoxy would be too aggressive for this application. I've listened to a few C-100s & AKAs over the last year or 2 & have always noticed the 'Tape 2' playing better in the reverse direction(<) & sounding quite muddy in the forward direction(>), every time. This was true for units that were 'professionally' serviced & I was always amazed at how terrible the sound was after such service.
Here is a video of the results after using my super long screwdriver & nail polish trick. I recorded music on a Maxell Normal(Type I) cassette for this demo, using a Denon 3-head deck with Dolby 'B' HXPRO. Feel free to comment any insights or thoughts about it.
My questions to other members here is:
1. Have anyone else who owns a C-100 or AKA, noticed the same phenomenon regarding muddy playback in the forward direction & sounding better but not great in the reverse direction?
2. After working on deck 2, has anyone else noticed the azimuth(alignment) of the head coming out of whack after a few songs of play on their Conions or AKAs?
3. Has anyone else used nail polish to secure the set screws after adjustments & if so, how well did it work for them?
I am keen to hear from others about this & how common or uncommon this problem is for them...
Last edited:
