Hey, got a Grundig Beat Boy 170 and although it is plastic it feels very robust. I changed the belts and the pinch rollers, but i have a Problem: The Speed Difference between the 2 directions is 40 Hz so That FWD Direction runs too fast and REV runs too Slow. I tried to get More pressure to the Spring of the FWD Pinch Roller but it didn‘t change anything. I cleaned and oiled Everything and it runs nice and Smooth, except this Problem. Second thing is, That i can hear the Motor humming in the Headphones. Does anybody Know how to fix That? it has a very Good Sound. The Speed Problem was also with the old pinch rollers. Also tried different belts but always had the 40 Hz Difference between the 2 directions. Cheers, Tobi
When measuring tape speed, have you taken into consideration all variation in speed from the beginning to end of the test tape? Tape speed will vary in the beginning, middle and towards the end of a tape on any Walkman, especially cheaper ones like the Beat Boy 170, it's something that you cannot fix. An explanation as to why one side runs faster and one slower is due to the auto reverse mechanism - I believe the speed variation gradient is just mirrored in the reverse direction. You should adjust the speed to achieve a compromise, it will never be spot on on a cheap mechanism like this model uses. Motor hum on this model is caused by faulty filtering capacitors in the amplifier section, I recommend just taking a 100uF 16V capacitor and bridging over the installed, old capacitors with it, while simultaneously playing something so the hum is audible. You will in short order find the capacitor(s) that cause the hum. It took me less than 10 minutes. The capacitors that are of concern are located here on the board: Note that the hum on this model will never go away due to cheap construction. It will always be audible on higher audio levels (above 6).
I Noticed on different Units, That one side is faster than the Other one, but it were 5-10 Hz, like on the Grundig Beat Boy 160, And this was even the cheaper Model, Not noticable if you Listen to regular Music but 40, sometimes even More, That’s More than a half Tone. If this was the Same when it was New than it would Not be possible to Listen to Music on it Daily for me. I mean That’s just crap. If you Know the Songs it‘s disturbing if it runs a half Tone too fast or too Slow. i can Not Imagine That. Especially because yes the Beat Boys were all budget Units Compared With something like a DD but it was the biggest Grundig Model in the 1987 Lineup and i bet it cost around 150 up to 200 D-Marks which was a whole lot of Money back than, so it should Play without those heavy differences. If this is normal on this Unit it is really Bad Construction and completely crap. The Chassis itself Looks very well Made, it‘s completely Made of Metal and much More massive than the Beat Boy 160 on which it is Not possible to get an acceptable Azimuth on both sides for all Cassettes. So it Seems That they are Both Not really usable for me. If the difference in Speed was not as Big on the BB 170 it could be the Perfect Daily machine for me but in this case it‘s just a case for the Trash and Not even Worth to find the humming, especially because of the headphone socket is phyisically broken and there is no was to find a fitting one without buying a second Unit :-( Thanks for your help. Tobi
I Tried your capacitor Trick. Didn‘t find any faulty C :-(. Which one was it at your Unit? I Guess someone around the Motor? May it‘s the wrong capacity? should the humming Go Away if i hold it parallel to the Right one? Cheers Tobi
Hi, no they aren't around the motor. The ones you're looking for are in the amp section, I will show you which one it was for me once I take pictures. Make sure you make good contact pressing the legs against solder pads, polarity doesn't matter for testing. Also the Beat Boy 160 is a mechanically superior unit to the 170, that's why it performs better.
Before ditching it I would try a belt from a good-running Grundig: yours here looks a bit thick and thinner belt would run at inner flywheel grooves giving different speed... BUT: auto-reverse Walkmans, as with cassette decks(except for the Nak, of course!), were the granddaddies of MP3 sound of nowadays... Once at right speed at Forward, you can worry about Rws Play, or Not!!! How much efforts does it take to flip a tape!?!?
Thanks for your help, but Nothing Changes if i hold the capacitor on those 2 Points. Similar Problem with my Sony WM 7, i tried it there and found 2 capacitors were the hum went extremely quiet when i held it on their solder points, but After changing them against 2 new ones it went Not better. If i try other capacitors the hum will Not be less... Beat Boy 160 also hums but Not as loud, May it‘s normal for it‘s cheap drive?! Cheers Tobi
Maybe, it's difficult to say. The 170 definitely has a bit of hum by default. If it's not audible during listening and only with no tape, that's normal. In my case it obscured the music and changing that cap made it subside.
It‘s definitely too loud for my Taste and it‘s also noticable, when a Tape is inside but it gets Louder when the Volume is turned up. On WM7 it‘s the opposite: it is loudest, when Volume is turned down and then gets lost in hiss if you Turn the Music louder but it is noticable until Volumes up to 6. It didn‘t help to change 2 of the capacitors. May it‘s a Little More quiet now, but it‘s still there.
