Hello everyone, I recently picked up a National FM15 boombox. I replaced the belts and gave the machine a good clean and it plays cassettes like it new, however when I record of live broadcast and play the tape back it sound's very low and distorted. I temporarily replaced the head with a similar one from a Panasonic RX-CT800 which recorded well before it died with a brand new blank cassette and got the same result. I have posted a few photos of the boombox and internal board. Anyone have any ideas on what else could cause this issue in a cassette player?
I'd break it down to three areas: 1. Tape - Guile, what tape are you using? Is it new or used? Check to make sure the foam pad is under tape in the exposed section. 2. Dirty Controls - A lot of old boxes develop problems with the function switch getting dirty, yours is sliding, these typically take FaderLube, rotating knobs take DeOxit https://caig.com/help-learn/ 3. Mechanical - The head may not be fully extending, if it plays fine, you can probably rule that out. I'd still make sure there's no extra friction when record is pressed 4. Electronics - This gets a little over my head but the ALC might be going bad. I think I have one of those out in the shop, maybe I'll bust it open and poke around.
I used brand new Sony EF 60's and TDK 90's tapes, Foam pad looks the same on all tapes. I'll have to get some Faderlube and try it. This will be my first time doing this, should I de-solder this switch from the board and take it apart to clean it or will flushing it from the sides do the trick?
It looks like from your photo there's some openings in the switch case, I'd start squirting in there first and on the top. There are some switches, I think rotary, that are closed up pretty good and you have to bend the metal taps to get access. I'd also try recording and play with the record button, press it while recording to see if you get a "bounce" in the recording. The problem is with the old equipment is that it could be several things, I like to rule out the easy stuff first since that fixes about 90% of it for me. Also look over the little tiny wiring for the heads, you may have pinched one of the wires, they tend to break really easily.
Thank you for that. Yes there is opening's on the sides. I will give it a go and report back. Btw I'm from Australia and I would have to order faderlube online which could take a while to arrive.. I was wondering since WD40 electrical contact cleaner is available at a near by hardware store would it give a similar result?
No, I'd stay away from it, I hate using it on just about everything except for shop equipment that I don't want to get moisture on. WD stands for "water dispersant" it collects dust and isn't a good alternative. Look up music or guitar stores, they will have something similar, the musicians use it to clean all of the knobs and sliders of electric instruments. Here's some local AUS Manufacturers. http://www.chemtools.com.au/product/aerosols/electronics-electrical/contact-cleaner-non-flammable/ It looks like WD40 has a similar product but they still use "WD40" in the name https://www.bunnings.com.au/wd-40-specialist-290g-fast-drying-contact-cleaner_p6100409 I've used CRC Cleaners on my cars and it's worked out great, I get mine at the local auto parts stores https://crcindustries.com.au/products/crc-co-contact-cleaner-350g-2016.html The contact cleaners get rid of rust and oxidation and they dry really fast, I think they will degrade carbon which is in the sliding switches, then you need something like FaderLube. I keep big cans of both and they last for years. Here's Arkay's Guide to DeOxit, he used to post on this forum all of the time. https://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/
I headed to Bunnings this morning and picked up the WD40 specialist contact cleaner and cleaned in the following order to try find out what is causing the problem. Cleaned the Tape/FM/AM switch a few times while moving it from side to side Cleaned the Record switch behind the tape mechanism while moving it up and down Sprayed all over the board front and rear Checked caps on board (everything looks good) Replaced head with one I had not tried before Changed back to the original head Recorded my voice through the mic (no difference) Is there anything else you would try?
HI.. How did you get the smaller inner belt off? There seems to be a small post with a spring on it keeping me from simply removing the smaller inner belt. Also where did you get your replacement belts? Thanks.
