Helix HX-4700 complete overhaul

Recently I did a full and complete overhaul on member Mac Daddy Freshness's (Adrian) Helix HX-4700. I acquired a 4700 from member Fresh Produce (Peter) some time ago and have been working on it. Since I have become somewhat familiar with this model, I offered to fix some of the problem's Adrian was having.



We modded this radio for Bluetooth some time back and Adrian has been rockin' the streets with it and although it can still get the job done, I would put it's condition in the "Daily Driver" category.

Repairs needed:

Broken off cassette deck A door
Broken spring tab on battery door
Bad deck belts
Missing antenna
Broken antenna mounting post
Multiple Broken speaker mount's
Broken case posts
Broken Mic Mixer knob pot
Creaky case
Creaky Handle
Filthy over all condition inside and out
Lots of loose wires
Horrible vibrations and rattles while playing at volume

As everyone knows, this era of radio, especially the big "Black and Empty" radio's suffer from lack of build quality and overall rigidity. My goal for this rebuild was to overcome as much of that as possible. I know from seeing / hearing and inspecting Peter's NIB Lasonic TRC-935 that these big black radio's were indeed at some point TIGHT and rattle free. But once they are opened up, all that goes out the window.

The goal: GET THAT FACTORY FEEL BACK.

It all starts with a full tear down, assessment and cleaning...



Removed the transformer and fully scrub the case inside and out.



Once clean, I pulled the handle apart completely. Of all my complaints I could have regarding this radio, like the discolite, it's right here in the handle. Although the handle of the HX-4700 feels solid and there is little threat of it breaking, it creaks so bad when you lift the radio that it's downright embarrassing. This is something I aim to fix. But it starts with a full cleaning. Dust and dirt in the gaps add to the creaking and loose feel.



This radio has been opened many times before. Infact when I first worked on it, it was missing screws and had miss matched hardware. Also, the wiring was a rats nest of loose wires all of which add to the overall BUZZINESS of the radio's sound. Having wires loose in the case is never good. Over time you may end up with wires rubbing on metal components and eventually shorting out. When I reinstalled the transformer I took time to zip tie everything in place eliminating the chances of wires rubbing, but mostly to keep them from banging on the case and causing noise during playback.



These wires are for the clock power and antenna connection. I will deal with them later.



The rear case had the typical paint splatter and grime. It took some elbow grease, isopropyl alcohol and a toothbrush to get it all clean. It came out REALLY good!



Time to pull everything out. I take pictures of where all the plugs go to make sure I know where it all goes when it's time to put it back together.




With all the electronics out of the front case, it's time to do some serious cleaning. The HX-4700 has many lines and grooves in the front that require cleaning with a toothbrush.



Once cleaned, the front case really started to show what this radio is going to look like.



The alarm system component's on this radio were all broken and loose. The red cover was another source of rattles and the prism inside was broken with parts moving around. All these things add up to what I call "Sound Fuzz".

Next up was to rebuild the hinges of Deck door A.



The biggest problem I faced here was, there was no way to reattach the old hinges and the new hinges hit the two cassette deck mounting posts. So lots of fabrication and adjustment had to be done.

Ultimately I had to file away some of the mounting posts to clear the new hinges, then build them back up and strengthen them with epoxy.



In the end, the decks fit back in, mounted up tight and the cassette deck A door was back on. The only thing missing were the springs that push the door open when you push the eject button.

The Mic Mix knob pot post was busted off on this radio...

More on that later!

EQ out for full clean and deoxit

Time to clean the chrome...

YEAH! The belts are here!



There are a few places where the amp slides into the front of the case. Even when mounted in place there are still vibrations from loose fitment. I glued small pieces of felt in place to fill the gap and tighten things up.



Same goes for the back of the tweeter bezels...

The biggest flaw of the HX-4700 is the single mounting post in the center top of the case. There are two other posts, one at each corner, but with it's central handle position, all the weight of the radio is supported on this one post. To make matters worse, this radio's center mounting post was partially broken and stripped. The damage made it impossible to get that center screw tight leading to a loose fitting case and a creaky handle / top case.

So, what I did was rebuilt the center post with epoxy, enlarging the whole area and encasing another post (from another radio) into the epoxy so the new screw would have a place to hold onto. I found a proper fitting screw to go in it.



This is not the final screw, I was using this one to align and straighten the post in the epoxy.

Next was to repair the antenna mount and fit two new antenna's.

The battery door had a broken spring clip, so using stainless steel sheet, I fabricated a new latch.



The aluminum battery door is one I had made for Peter some time ago for the 4700 that I now have.

Back to the biggest issue with this radio and many others like it.

CREAKY, SQUEAKY plastic on plastic!

I HATE RATTLES and I HATE SQUEAKS!

This radio had those in spades! But I found a permanent way to fix it. I picked up some very thin fabric called ULTRA SUEDE. It's a synthetic that doesn't have threads to run and doesn't deform when used with a hot glue gun.

If you have ever pulled the dash board out of a new car to install a stereo, then you most likely have noticed that every joining surface is covered in a thin layer of felt. This prevents the plastic from coming in contact and making squeaks in the car. I basically did the same thing.

I found all the surfaces that touch or rub and put this ultra suede between them gluing them in place with hot glue gun all along the rim of the case sides.

The difference is MIND BLOWING!

This simple fix has transformed this radio from a cheap feeling creaky rattle trap to a super tight premium box.

I also put some felt in the handle hinges and rubber bumpers where the handle rests in the down position, further eliminating rattles. The combination of the top center post fix, handle fix and case seem fix have completely transformed this radio.

Getting back to the broken Mic Mixing Knob.

I unsoldered the knob pot from the EQ PC Board and through conversation with member John (Beosystem10) he was able to go to a local electronic components store near him in the UK and find the correct part. I ended up pulling the pot off of my HX-4700 and installing it into Adrian's box so he would have a fully working unit while I await the part from the UK.

A Huge THANK YOU goes out to John for taking the time to drive across town and research this part and mail it to me. Another reason why these projects are even possible and his efforts go to helping Adrian get a fully working radio.

The final product barely resembles what we started with. Without a doubt this was the most comprehensive tear down and restoration I have done to date. I have done all these steps to other radio's just not all to the SAME radio. It took everything I have learned plus inventing a few new tricks to bring it back to "Like New" condition.

This radio was a horrible squeak rattle trap.

The rear cassette storage door either popped open when you didn't want it too or wouldn't open at all. The latch was fully rebuilt and it works as it should.

The decks were fully rebuilt and play as they should.

Two new antennas were installed and mounting posts rebuilt.

All wiring was tidied up and tied down to prevent rattles

The deck door hinges were repaired

All the components of the alarm were secured to prevent rattling.

The dents were hammered out of the woofer grills and they were re-painted gloss black.

The handle and case were tightened up and in the end, this is the tightest radio I know. When you lift the radio up, there is NO SOUND at all. You can hang it from the handle and wave it around and it is completely silent.

I will be doing the ultra suede seem fix to ALL of my big black radios for sure! Look for a future thread on step by step instructions, plus video, on how to make that repair.

On final assembly, I played a Frequency Test through the stereo to track down any last offending rattles or vibrations. This is a great way to find out what is moving.

These black boxes suffer from rattles that translate to audio output. Every rattle and vibration becomes part of the audible sound you hear. Eliminating those rattles and vibrations pulls those frequencies out of the mix, cleaning up the sound output. The sound quality of this radio has improved exponentially with these fixes.

I think the final product speaks for itself....

One last thing to mention....

Obviously, a lot of work went into this restoration. I have probably 25-30 hours if not more invested.

Since I have been on this site, many people have helped me out and most recently, members bklyn sound, THAFUZZ, Beosystem10, superlew, Mac Daddy Freshness, Fresh Produce and blu_fuz (to name but just a few) have helped me out, asking NOTHING in return!

Some have hooked me up with impossible parts finds, some have mailed me parts FREE OF CHARGE!

And although it may be hard for me to repay them back directly for one reason or another, the only thing I can do is pay it forward.

So, I just wanted to say THANK YOU to all that have contributed to me in the past. Know that your efforts were with me in spirit as I past that "Blaster Karma" forward into this box and along to Adrian (Mac Daddy Freshness) who is a super nice guy and very deserving to have a fully worked out Helix HX-4700.

Now I have to go do this whole thing all over again on my 4700

Wow!

Great job Chris!

The man! Excellent work! Chris is boomboxery.

Looks brand new! Getting a big, black box to feel solid adds $$$ to its value..

Chris!! I cant thank you enough man you really outdid yourself on my Helix i can finally bust out my haul of Cassettes and piss everybody off LOL But good things are coming your way man

Holy **** i wish i had the time these days!

Fantastic work Chris!!!

Pinned!!!

Thanks guys, this is one I am very proud of. I wish more than anything you all could just pick it up off the ground to feel how this box feels. It's simply amazing. I never thought ANY big black radio from this era could ever feel this solid.

mac daddy freshness said:

Chris!! I cant thank you enough man you really outdid yourself on my Helix i can finally bust out my haul of Cassettes and piss everybody off LOL But good things are coming your way man

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I'm glad your happy with it man. It makes me feel good knowing your gonna be out there delivering the goods with this beast. It has another 25 years left in it for sure. Thanks for everything you and Peter have done as well. You guys are the best! Just my way of paying you guys back and passing on some of the kindness that has been bestowed upon me from all the great members of this site.

That is absolutely awesome work man! Very detailed, and super- super informative! I'll be coming back to this thread a couple of times to figure out some fixes of my own. Kudos!