Bombeat 40 -- on it's journey home.

[Superduper]

Well, as you all know -- I've been working on this Toshiba for Ira. The work was pretty straightforward. Most of the delay is due to waiting for parts, waiting to decide what to do and how to approach, waiting for Ira to make a decision, yada yada yada.....

Some issues and observations that Ira and I decided we wanted to address:

(1) FM stereo tracking was off so sometimes stereo, mostly not.
(2) Power/Function switch was finicky and unreliable.
(3) AM was sometimes good, sometimes not good.
(4) Tape deck would FF & RW but would not play and heads would not engage
(5) Old guys get rather deaf, especially in the high frequencies so Ira wanted the lack of treble looked into.
(6) Right VU meter had dead segment which was annoying (me more than Ira)
(7) Power jack was designed such that it would always spring back to 240v when cord plug is inserted straight in. To get 120v, you needed to insert cord plug part way in and shift selector to the spring loaded position.
(8) General replacement of electrolytic capacitors with purpose of taking a proactive approach to improve reliability and restore original performance levels.

All issues have been resolved and while I can't say that it is the loudest or best sounding boombox in the world, I am confident that it is now performing like it was intended to, but better!

I wanted to wait but Ira insisted that I post some photos up tonight. Pushy old man, he is. And an impatient one as well...

Photo of just completed boombox below. Details of the work done to the boombox will follow......

 

[Superduper]

------------------------------

ANALYSIS OF ISSUES:
(1) FM stereo issue was determined to be caused by the pilot signal being out of adjustment. It was adjusted and now, FM tunes true all the time and stays centered without drifting.

(2) Power function switch was cleaned with deoxit with no improvement. With the cover off, arcing could clearly be heard within the switch. Those mini lighting bolts can do a lot of damage, especially when you can hear it zapping. Switch was removed and disassembled. Then inspected. Significant charring was evident. This is a 6-pole 3-throw switch . It is like 6 switches in one with 3 different positions for 18 posible switch positions. After cleaning and polishing, it was apparent that little slide feeler switching the power pole was severely eroded. Not only was the feeler eroded, the actual switch legs were eaten away too to where not much contact surface remained. Even if a replacement feeler could be found or fabricated, it was clear that reliability would always be an issue. It was a poor design and that signal level switch should never have been used as a power switch.

This is the switch that needs to be rebuilt. It is packed tight in there, and has 34 legs that needs to be desoldered.

Look closely, and you can see the charring and burnt power switch

The larger piece is what the slide contact is supposed to look like. The smaller piece is what is left of the eroded piece.

The contacts have been cleaned and polished. Normally, a switch that is rebuilt like this can be expected to perform like new for another 30 years. However, on this one, the legs are eroded too. Therefore, it can not be reinstalled and expected to perform reliably. The leg surfaces are no longer flat and won't be able to provide good contact for the slide feelers.

THE FIX: Redbenjoe said "if you're gonna move the power switch to the side of the boombox, it's a no-go." Not that the thought of such a retrofit ever crossed my mind, but the challenge is clear -- how to retrofit/install a switch that is sturdy enough to handle the power requirements of this boombox and yet not affect the original look and condition of the boombox? Solution: Replace the existing switch with a donor switch from Bombeat 12 boombox. Offload the power switching responsibility from the switch, which is really designed for signal level currents anyhow and not power current and retrofit a relay into the system to handle the heavy loads. The switch therefore will only control 60mA instead of 3-5 amps (3,000 tp 5,000 mA). Do the math -- it is a huge reduction in current carrying load to the switch and should allow the new switch to last for a very long time.

So........ Build my own custom relay module, with provisions for LED dial lamp. Here, custom PCB with traces drawn with etch resist, drilled.

Board is etched and copper removed, resist cleaned off

Populated, Assembled, soldered.

Traces are tinned to prevent oxidation and corrossion of the copper traces.

The original power cables disturbed me. They are those skinny red/black wires. I am replacing them with the much heavier guage cables that will go directly to the relay module, then to the boombox main PCB.

Wired and ready to be fastened down

Self adhesive standoffs will allow the module to be secured without resorting to drilling screw fasteners through the shell.

The module works flawlessly. There is a slight 1/4 second (or so) delay when turning on the boombox but there is no switching noise, etc. Also, the relay is much easier to find replacement parts for when and if the time comes rather than expecting to find another donor power switch. On AC, the relay is rated at 10amps/125vac and at DC, is rated at 5A/30vdc (150watts). Since we are only switching 16vdc, this relay should perform fine.

 

[Superduper]

(3) The radio band switch was oxidized which was resulting in poor contact and low audio signals, especially on AM, and some contact cleaner resolved that issue.

(4) The cassette mechanism: It was determined that the mechanism was missing a small gear. Normally, when the play lever is depressed, the heads are actuated up 1/2 way, which activates the flywheel that turns a small gear that rotates the head assembly the rest of the way. That gear was entirely missing. Can't "fix" a car that is missing an engine, so there is no "fix" for this. The solution was to find a donor cassette and thank goodness for the Bombeat 12 donor box (courtesy of Monolithic). This boombox has become a sacrificial lamb. The deck wasn't 100% identical but the "bones" was the same. Swapping the different parts on the decks were necessary to make it work, but the transplant was a success.

(5) Ira said the boombox had no highs. The tweeters were definitely working -- you can hear them when you put your ears up against them. But they were not working well. The high-pass filter caps were replaced with Nichicon Muse audio grade bipolars and the treble performance did improve somewhat. Thinking that the tweets could handle a bit more mid-range, especially since there was a pair of them, I decided to (A) increase the value of the caps and (B) use higher voltage varieties. This time, I only did the swap on 1 side so I could do an A/B test and the larger valued ones were clearly superior so they were swapped in. In my living room sitting 25 feet away from the boombox, the highs were clear and bright and I had no problems with what I was hearing. In fact, some sibilance of the audio is noticeable with the treble turned all the way up. I have heard boomboxes with better highs but I believe this one is now performing about as well as it can with these current drivers.

(6) Right VU meter had a blown segment in the LED module. It was a 5-LED module so to remove it took some microsurgery to cut out the bad segment, but that was replaced and it now lights true all the way across. This "fix" pleased me probably more than redbenjoe, who was rather indifferent about getting that fixed. To me though, it just wouldn't be right if it wasn't fixed.

Look closely at the foreground and you can see what the original LED's look like. They are monolithic 5-led modules molded together.

The bad LED cut out and new one installed in it's place.

(7) The power jack: Inserting the cord is always an annoying task. First the default position is 240v straight in. To get 120, you insert cord 1/2 way, then slide the selector and push in the last 1/2. Since this boombox is likely to stay here in the states, it would be valuable to switch the position so that straight in would be 120 and the alternate selection is 240.

Power supply removed, filter capacitor will be replaced and wiring swapped.

Power Supply recapped, and rewired.

Selector plate will be relabeled so there will be no confusion what the voltage is

Finished. Default is now 120 volts.

240 volts is selected by sliding the selector plate so dual voltage is retained.

 

[Superduper]

(8) With this boombox making a 3,000 mile journey here, it was prudent to replace the electrolytic capacitors. This is a proactive approach to ensure that the boombox is (A) performing as original designed and intended and (B) reliable enough to go another 30 more years and avoid another trip around the world.

I forgot to photograph the main board so no pretty pictures to look at but here is the LED driver panel re-capped.

Before:

During:

After:

(9) LED mod. BE CAREFUL WHAT YOU ASK FOR -- Ira learned this the hard way. Because........ He did not like this experiment one bit. In fact, he said no-way so many times I had to remind him my name was Norm and not Jose!

Ultimately, we settled on this: Side lit rather than top lit.

Of course redbenjoe also special ordered a hidden switch too. That way, the lamp can be powered on all the time, or when he's getting cheap on batteries he can get an extra 10 minutes of operating time by switching off these cool lamps.

Switch installed into a recess on a support bracket.

Bracket then installed behind the battery compartment and accessed via a small hidden hole.

Because there was not much room, special surface-mount-leds on flexible ribbon was utilized.

 

[floyd]

norm you are awesome dude !

 

[sony_apm_fan]

Superduper, wow, I am simply in awe of your talent here. :super:

Amazing. Simply amazing. :super:

Thank you so much for sharing this with us all.

 

[Superduper]

The front part of the video is a functional demonstration. The end is just some 360 views filmed by daughter who couldn't take her hands off the video camera, and takes a few minutes so you can just ignore the end portion as it can get quite boring.

Showing....
Cassette working
Radio working AM/FM and FM stereo
Line-in working.
Function/power switch working reliably
Tweeters seems like they have good treble performance, hmm?
Dial light and the hidden secret switch.

[youtube]jR9XXO6XQoM[/youtube]

 

[blu_fuz]

I am sending the dynasty, like now. Great job!

 

[hemiguy2006]

WOW !!!!
I remember when Ira surprised us with this box at the sunshine mix.
I kind of felt kind of bad at the time because everybody was so wowed by the rare bird,
but its functionality really left much to be desired.
Nothing like showing off your newest find and then really fumbling to get it to work so you could impress your friends.
I remember him mentioning that it was a bit of a junker, or maybe a beater was the word he used.
Any how I could clearly see that this box could and should be much more than it was.
I am so happy for Ira , he really deserves this box.
And now he can not only say he has the only one in the states , but he can say he has the best one in the world!!!!
Norm , you did an excellent job on this box and I was getting all choked up watching the vid.
It was very kool that your daughter got involved in filming it with you.
It was also very kool to see it fully functional and a full set of leds really put a smile on my face, even more so than the dial lights.(they are way kool as well).
I am proud to have been a part of this project and am very happy to see it making its final Journey back to Fl.
Ira hit me up when it arrives we will have to plan another mini meet soon!!!!

 

[jaetee]

Having seen and heard that box first hand, It's amazing what you and Frank were able to do with it. Seriously.... I'm in awe and completely speechless!

BTW, I heard a rumor that Ira was gonna sell it to a guy in Houston.

 

[Fatdog]

I'm not crying. I just have something in my eye.

:super:

 

[reptoid]

simply amazing

 

[skippy1969]

I'm not crying. I just have something in my eye.

:super:
Well if your not crying Bobby,I am,,,,,,, :'-(
I'm just in awes at the awesomeness at what you just showed us Norm.....
You are DA MAN!!!!! :super:
I still can believe it.........

 

[Gluecifer]

You've raised the bar to new and very lofty heights Norm!
That's some really wonderful work on an equally wonderful radio.

Now, with your knowledge and experience around thise glorious specimen,
could you please do sound comparison to other radios?

PLEASE!!??


Rock On.

 

[oldskool69]

I'm not crying. I just have something in my eye.

:super:

Screw that...I am crying! Norm...if you weren't #1 in the rankings you just shot right past #1 to some number I can't fathom.

 

[redbenjoe]

Having seen and heard that box first hand, It's amazing what you and Frank were able to do with it. Seriously.... I'm in awe and completely speechless!

just read all these gracious comments --

chose to quote jaetee --which is how i think --except i am NEVER speechless


i want to re-thank frank for the equally awesome work on all the knobs and all the glass and all the chrome and all the panels
and then --what about that incredible gutsy mold job for the tweeter cover re-build

and thanking mono for providing us his bombeat 12 --which SAVED it

and my old buddy ramon who first brought it from basket case to functional
as when we first saw this local florida beach beater --
it looked and performed like the first owner had used it as his kids sand shovel//lunch tray combo :'-( :'-(

more on next post

 

[MasterBlaster84]

Top notch Norm, wish more of us were that good at fixing these beautiful relics.

So what do you do for fun in your spare time?

 

[mellymelsr]

Wow!!...Norm you have outdone yourself. I have been lucky enough to see some of Norm's work first hand and this is amazing work. Every time I talk to him he scrambles my brain with the amount of technical information he knows. Great work Norm...another grail has been saved by :super: ...

 

[redbenjoe]

part of the challenge for norm was to make it a 100% original tosh 40
retro-fit --so that everything could go back to factory original --
so -he DID THAT !!!

also want to mention that cool // humble norm has done this same awesome
careful // quality work for LOTS of us members and saved LOTS of old grails-
but they were not quite as dramatic as this public project
------------------------------------

he is away today --and i know rick and perhaps the rest of us are interested
in the ' how it sounds // compares ' scenario

from 3000 miles away --here is my interpretation of norms evaluation

get TWO 67 vettes --- a 350 HP small block vs a 435 HP tri-power big block
start them off the line at the bottom of a san francisco monster hill

the small block will surely hang in the zero to sixty tests-
but the big block takes over after 60 and way beyond that

so ...............the tosh sounds beautiful //wonderful and all that
up to a semi- loud point --
but the fabulous m90 is still the undisputed KING of the one piece power-house grails

so then all you lucky m90 owners --
and we sure do have PLENTY -- :'-(
can relax and hug your biggies
it IS #1

 

[blah blah]

what a great project. has to go down as one of boomboxery's most classic success story of teamwork and technical mastery.