A short time back member Fresh Produce and I made a deal and I acquired this Helix HX-4700. It's a tad smaller than a J1 and around the same weight, but by no means the same quality of the J1. I worked on it last year for Peter making a battery door for it. But it had all kinds of problems.
First, the system would not power up on batteries, but the problem really was in the fact that the previous owner used 10 different screw's, some wood screws, some phillips, some flat head, some metal, some way too long some too thick to hold the back case on. Getting them all out was a mess and took some time.
Once all the screws were out, it took some deoxit on the AC switch where the power cord plugs is, a very common problem on these old radios and it started working on batteries.
But that was the least of this radio's issues. It's biggest problem was the fact that the whole radio seemed very low on power output and even more so on the left channel. Also, if the radio was jarred, by banging on the top, the volume would come up, sometimes staying up, then the next time you moved the radio, back to crap!
This weekend I spent about 5 hours with the back off looking through the radio for a possible culprit.
Here is what I found...
At some point in this big blasters life someone spilled a soda into it. The PC boards had soda on them and smelled of caramel. I cleaned them all with 91% isopropyl alcohol and a soft brush.
In the cleaning I found a lower PC board that had been covered in soda also had 3 bad solder joints at a connector where the speaker wires attach. This PC board houses the headphone and mic jacks below the cassette decks. I resoldered them and vola, SAME PROBLEM!
OK, back to tracing lines. I then found that the left channel would come to life a little if the EQ sliders on the low end were moved around. Out came the EQ for a full clean and deoxit.
Reinstalled and there was a slight improvement.
I then found a connection between the amp and the EQ that was below the top PC board that seemed to be the problem. It had 6 crimped connectors inside a larger connector plug. It was full of gooey soda. I cleaned it all and YEP, that was the MAIN problem.
I hit the knobs with deoxit and got them all freed up and the sound came through at full volume.
One thing that is very interesting about this radio is the LED meters. They sit right above the EQ and do the strangest dance I have ever seen on a boombox.
With the EQ out I was able to gain access to the back of the LED display. From there I was able to trace the wires to the main board. The interesting thing is, there are only 3 LED's! One in the middle and one at each end of the meter line. The thing is, what looks like LED lights are infact prisms. And the lights don't seem to flash for any particular reason.
The light in the center is clear in a blue sleeve, but it shows as green on the front of the radio. The left LED shows as orange on the front of the radio and the right side doesn't work. It appears there maybe a bad diode some where as they are all getting power, but the right one is getting 14 volts and the center and left are only getting between 4-7 volts. So that needs to be dealt with.
But they don't really flash to the beat of the music and sometimes they don't flash at all. So, not sure what's up with that. I may scrap that design and build something better and brighter as these are very dim.
The alarm does not seem to work, so I will play with that in the future.
A side from that, the box performs well now. It's still a big creaky heavy beast. Next time I have it open I will take off the handle and see if that can be worked out.
Both decks do work, but the sound quality is as if the heads are worn out. It does have a line in and I have modded it for bluetooth. The FM stereo comes in loud and clean. AM / SW 1 / 2 work as they should.
Next, I think I'm going to swap in some Lasonic 931 woofers and tweeters. It actually has 6 speakers, 2 woofers, 2 mids and 2 pizo tweeters, but I swear the woofers are just connected at full range and the sound is harsh.
The pizo's have to go, a nice set of tweeters and mids would make a huge difference and choking the woofers off in the correct spot would help a lot.
It's coming along...
First, the system would not power up on batteries, but the problem really was in the fact that the previous owner used 10 different screw's, some wood screws, some phillips, some flat head, some metal, some way too long some too thick to hold the back case on. Getting them all out was a mess and took some time.
Once all the screws were out, it took some deoxit on the AC switch where the power cord plugs is, a very common problem on these old radios and it started working on batteries.
But that was the least of this radio's issues. It's biggest problem was the fact that the whole radio seemed very low on power output and even more so on the left channel. Also, if the radio was jarred, by banging on the top, the volume would come up, sometimes staying up, then the next time you moved the radio, back to crap!
This weekend I spent about 5 hours with the back off looking through the radio for a possible culprit.
Here is what I found...
At some point in this big blasters life someone spilled a soda into it. The PC boards had soda on them and smelled of caramel. I cleaned them all with 91% isopropyl alcohol and a soft brush.
In the cleaning I found a lower PC board that had been covered in soda also had 3 bad solder joints at a connector where the speaker wires attach. This PC board houses the headphone and mic jacks below the cassette decks. I resoldered them and vola, SAME PROBLEM!
OK, back to tracing lines. I then found that the left channel would come to life a little if the EQ sliders on the low end were moved around. Out came the EQ for a full clean and deoxit.
Reinstalled and there was a slight improvement.
I then found a connection between the amp and the EQ that was below the top PC board that seemed to be the problem. It had 6 crimped connectors inside a larger connector plug. It was full of gooey soda. I cleaned it all and YEP, that was the MAIN problem.
I hit the knobs with deoxit and got them all freed up and the sound came through at full volume.
One thing that is very interesting about this radio is the LED meters. They sit right above the EQ and do the strangest dance I have ever seen on a boombox.
With the EQ out I was able to gain access to the back of the LED display. From there I was able to trace the wires to the main board. The interesting thing is, there are only 3 LED's! One in the middle and one at each end of the meter line. The thing is, what looks like LED lights are infact prisms. And the lights don't seem to flash for any particular reason.
The light in the center is clear in a blue sleeve, but it shows as green on the front of the radio. The left LED shows as orange on the front of the radio and the right side doesn't work. It appears there maybe a bad diode some where as they are all getting power, but the right one is getting 14 volts and the center and left are only getting between 4-7 volts. So that needs to be dealt with.
But they don't really flash to the beat of the music and sometimes they don't flash at all. So, not sure what's up with that. I may scrap that design and build something better and brighter as these are very dim.
The alarm does not seem to work, so I will play with that in the future.
A side from that, the box performs well now. It's still a big creaky heavy beast. Next time I have it open I will take off the handle and see if that can be worked out.
Both decks do work, but the sound quality is as if the heads are worn out. It does have a line in and I have modded it for bluetooth. The FM stereo comes in loud and clean. AM / SW 1 / 2 work as they should.
Next, I think I'm going to swap in some Lasonic 931 woofers and tweeters. It actually has 6 speakers, 2 woofers, 2 mids and 2 pizo tweeters, but I swear the woofers are just connected at full range and the sound is harsh.
The pizo's have to go, a nice set of tweeters and mids would make a huge difference and choking the woofers off in the correct spot would help a lot.
It's coming along...
fftopic:
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