A classic mistake? Attempting to fix up a Sharp GF-9191 

Chain linking several not very good ’boxes, all with dodgy batteries, to make a mighty racket on the move was the true sound of the very early eighties.

True

100% agree. As a kid I had a Sony Beta VCR that had audio dubbing & video editing features and the back was plenty of I/O connectors. Those were fun times!

That's why I designed and built my own stereo with 8 inputs and 4 outputs. (Although, I forgot to put a headphone socket in there and it's too much trouble to unplug everything and install one. LOL)

​@@AseGarciaYeah, they were. When I was a kid I made videos of like NES gameplay with an audio mixer and dubbed in music and narration and stuff lol.

The exasperated sigh when he first tipped it was a mood.

I read that in Blackadder's voice

When the screws fell out, I heard DankPods voice in my head saying, "Someone's been in 'ere!"

Cars, electronics, packages in the mail containing glass... three things where I've said the same thing.

Exactly my thoughts. He used to say "I don't do repairs, just some minor touchups" but look at him now! Really awesome to see

Agreed! If that were me that tape deck would have never gone back together 😂

Mend it Matt

@@DjZelous ... but without Mark's awesome workshop and decades of experience!

Hi great repair ,I’ve got to tackle mine yet ,just working on a hitachi,the sharp gf 9191 was the boombox used in the clash rock the casbah,they only made it in silver and grey but in the video it’s red so it must have been custom painted,cheers Ade

You can buy the belts and wheels because they're fairly standard parts. That's a great thing!

@@AnnaVannieuwenhuyse That's not quite the reason. These parts are available now because there's demand for them from the retro audio community, so some enthusiasts and the Chinese are producing these pinch rollers, idler tires and belts and gears. Most of these *were* standard parts, but they are not used anymore in todays electronics. Today, good quality flat belts in high quantities are only produced for turntables, and I can't think of anything else mass produced consumer electronics that uses belts, apart from the tray mechanism of CD/DVD/BD players. The belts, idler tires and gears in these high quality repair kits are being manufactured in low quantities in Slovakia, Hungary, Poland, maybe Germany and I guess probably also in the US. And you can also get the cheap but questionable quality ones from China. I think pinch rollers are only being made in China, some of them are of good quality, these European parts sellers source them from reliable Chinese producers and usually test them one by one prior to selling them. Chinese belts are not recommended, I tried multiple sources and usually 1 out of 10 produces bearable wow&flutter.

@@mrnmrn1 small belts are still used in devices made today, so they are in demand because they are being used. And if it exists, why not use it?

Way ahead of amstrad junk

@@AnnaVannieuwenhuyse Yes, that's what I said. Tray mechanism of CD/DVD/BD players. I can't come up with anything else that uses belts nowadays.

Good gosh, it is! Been happily watching not even paying attention that it’s been near an hour.

Something else to make people feel old. Free as a bird by The Beatles was released in 1995, now 28 years ago. In 1995 The Beatles had been split up for 25 years....

Almost to the day to boot!

That’s cheered me up no end!

I think a lot of the assembly was automated A lot of that automation is lost technology now

@@qlue7881 … nope. Apart from the circuit board printing, these units were entirely assembled by hand.

This boombox is actually quite simple internally compared to many others, and there was never any automation in the assembly of boomboxes

@@adammcmichael4799 They’re all relatively simple internally, even the top end models. The first time I saw a JVC RCM 90 opened up, I was very surprised by how basic its innards were.

I assume when you would be working the line for 12 hours a day it would become much simpler than it looks

never throw out old toothbrushes!

I got myself an old Oral B Pulsonic Slim toothbrush, the battery needs replacing, well I use it for cleaning small things, it's not a miracle tool though.

Also used interdental brushes would've been great for cleaning that gunked up capstan hole.

@@YS_Production Yes, using all those sticks seemed a bit of a waste to me.

Also paint brushes for more gentle cleaning.

I had the GF8585 around the same time, great sound qulity

Very uncommon but indeed useful to have a phono properly plugged in 😊

What I'd like to know is if there was a Sharp portable phonograph designed specifically for this boombox

An am station switched to FM for one program?

​@@taxirob2248lol probably not. But i don't know what that would have looked like. A record player doesn't really care what you plug it into.

Mend it Mark is another great RU-vidr! 👍

Not taking away anything TM does, but Mend it Mark has an excellent technical back ground in electronics and engineering.

It that the same person as Mark that works with RMC?

Mend it Mark would have it in perfect working order, before he put it back together. 😛

Props to you for working on this kind of equipment. It looks absolutely bonkers.

"Here's one I started earlier." And, of course, "Sticky-backed plastic."

"WD-40 was originally invented in 1953 by a chemist at the Rocket Chemical Company as a rust-prevention solvent for Atlas missile outer skins." Oh. So there _are_ benefits to military research!

@@caddelworth And the 40 is because it was the fortieth version of the water dispersant they tried that was eventually successful.

Both good suggestions, based on experience no less! I use D40 for de-stickering a lot because it softens the adhesive, and almost never affects the base plastic or paint. As far as tape rollers, I avoid D40 or any other rubber rejuvenator. Lots of sources for this. The rubber may be happy, but anything oil or petroleum based is bad for the tape itself. Softens the binder and the iron/cobalt particles peel right off.

I still have that same exact machine, sporting that weird brownish tan, which I bought round christmas '84 (if memory serves). I gave it a bit of an overhaul a few years ago, basically new belts and a new micro-switch for the cassette mechanism, so it's in good working condition again. Back in the day, I used to take it to our practice space to record our band rehearsals. And guess what? On my way home, I pretty much did the same thing you mentioned above: crank that mofu up to the max... and confront the unsuspecting public with our latest strokes of sheer musical genius. Looks like that machine was made to annoy pensioners... 😂

@@kiwibass Yeah, 19yrs old & strolling out with tunes blasting at max volume, great memories. Only downside was batteries 💸😂. I had the grey back/silver front version, looked really good & was by far and away the best machine I owned in respect to sound quality, better than the more expensive multi speaker machines I owned prior to it. I must have just fallen onto a nice example 👍

Agreed - or use Sugru instead of the shrink tubing, which has the advantage of filling in any small gaps. But definitely re-use the parts that have broken off!

Personally would have glued the posts back together when possible and secured them with suitable size zip ties, they can take a lot of strain.

I was very impressed that the Sugru repair worked at all!, … the original plastic looks like it was most likely a Polystyrene … which does degrade over time. Personally, I suspect someone had previously opened the thing up to try and fix the tape … quickly given up and then not been careful enough when refitting the screws … you have to remember the original holes were simply blank pilot holes and the screws are self-tapping … it’s very easy to cross thread them when replacing them. In addition, the strength of the plastic will have aged such that the threads will easily strip and the posts will burst apart (as seen!) if over tightened. Getting a good adhesive bond to this degraded polystyrene is difficult … surfaces need to be really clean (need to thoroughly degrease with IPA), lightly abrade to roughen up any smooth surfaces … another IPA wash and choose a good epoxy based system to mould the new posts. I wouldn’t recommend using the broken bits as they will still turn to dust when you try screwing into them … the threads will simply strip out. I think the best option would be to create simple moulds to reproduce the largest diameter of post possible (10mm ??) centred on each stump, then pot the mould to build a solid post of epoxy (5 minute Araldite should be ok if you’re impatient) … let the epoxy cure, then drill out new pilot holes and grind down the tops of each post to the correct height. Bit of a palaver .. but more robust. An alternative to standard epoxy adhesive would be something like Plastic Padding … which is an epoxy adhesive with a filler compound mixed in (gives it the grey colour) … but I’m not sure how good it would be at bonding to the Polystyrene .. 🤔

Thanks for the tip!

Was thinking the same thing, I used to occasionally use a 2 part rawl plug putty and would put the screw in when the putty was soft to create a thread then take it out as the putty firmed up a little, then re-attach with whatever I was trying to fix to the wall once the putty was fully hard.

Agreed. I would also have used liquid poly to re-attach the "rattling parts" before doing the Sugru build-up. FYI: I used Sugru some years ago to "mod" the cover plate for an iron (as in: for ironing clothes!) so that it didn't fall off. Several years on … it's still going strong and showing no signs of wear, going soft, or any other problems. 😉

@@brianthomson6012 . Rawlplastic is no longer available, at least, I couldn't find it online...I believe it used to contain asbestos.

Even better still, an old head from an electric toothbrush!

Lol "decommissioned". I love reading the comments section of this channel.

...or your current one. Just be sure to get the food particles out of it first. 😬

Good Call!!! JB Weld makes a tough marine grade epoxy putty...tough as nails but stinks to high heaven!!! 😂

Excellent advice. That putty is extremely hard and tough.

This is the thing, epoxy putty has a great mix of rigidity and resilience, and can still be threaded by typical self-tapping screws used in these devices. I've had great results with similar machines and even laptop hinge mounts which have much worse stress.

I standardized on C60, and just left out the tracks I loved the least.

Yep. many's the 'five-pin DIN to two phono' cable I soldered up back in the day.

@@Tim091 Maube you could clear up an ancient question for me: I had an ITT stereo radio and a Japanese cassette deck when I was a kid around 1979. The radio had a DIN socket, the deck had phonos; connecting them for recording produced lower recording levels than optimum. Would that be some kind of impedance mismatch between the two?

I use Sharpie markers. A mark next to each hole and on the screw. Learned that trick doing recall circuit boards in Honda stereo/ nav headunits years ago. So many screws in those things, almost none of them the same.

I would have to confirm by watching the video again, but I think I remember seeing a pop-up note in the lower right corner that he said he lubricated everything he just didn't show himself lubricating the moving parts. It was already a very long video for his typical length videos. Anyway perhaps when you have time you can watch it again and look for said pop-up in the right lower corner 😊.

regarding the wobbly play back I could see what looked like liquified rubber gunk all over wheels in the mechanism that were nowhere near any belt paths. That stuff will be what's causing the issues I'll wager

I see something.

@17:26 too.

17:28 It almost like there was a rubber belt of some sort.

yeah same with me but i have walkman.

Yeah, I got a copy of the boombox I had as a teenager in the early nineties after his last boombox video hit me in the feels. I lucked out and for £70 got a fully-working, immaculate one on eBay and a near-perfect matching remote control for it for £25. I was a bit disappointed it didn't have anything that needed fixing or even cleaning.

The problem is probably that the new belts are not manufactured to tight tolerances.

Im using lego- pneumatic tubes for this, works well (-:

Yes, it's the rubber tubing that is the weak link. It's out of round. Just need to find something from another device that uses high precision rubber.

I'm still repairing cassette decks professionally and I agree with your sentiments about Sharp cassette mechanisms with the rubber drive inside the capstan assembly. I've had to deal with a number of the home stereo cassette decks in the past year and every one of them required the rubber drive to be replaced. There's a seller on evilBay who has the correct rubber tube that is the correct length and machined to proper tolerances along with a replacement tyre for the idler wheel.

Agreed and I think this is where his problem is, leaving it playing for a few hours will settle the tires and pinch roller also that tire on the capstan may be binding. All in all a good effort they usually need a second fettle.

You know, I've always wondered why Mat _doesn't_ use a "dim bub" tester when he plugs some new piece of weirdness into the mains socket for the first time. They're easy enough to make (well, OK, you DO need an incandescent bulb!), and they can and do prevent expensive ElectroBOOMs.

Comfort watch

Hey come on now, you're destroying the stereotype of older people being technologically clueless.

Damn, I just bought some. Guess I need to get some Deoxit as well.

@@owenvogelgesang7314 industrial supply houses should have a cheaper contact cleaner, I got some from Grainger here in the states. Deoxit is made, marketed and priced for hobbyist$.

@@owenvogelgesang7314 Sometimes it's ok but others it will rot things

@@taxirob2248 Problem is you don't need a lot of it, so price has to be high

@@owenvogelgesang7314 It's OK for generic board cleaning and for degreasing plastic and rubber parts. The can states that it's safe on plastic and rubber, which is not true for brake cleaner and some other flux removers for example. BUT it seems like it even damages potentiometers, it dissolves the carbon track if you wipe it too much with it.

A play on ZZ Tops track 😆

I was going to suggest the same. Epoxy putty, and using the original screws (with a smear of vaseline on the threads) to form around.

Once it's set, Sugru is *much* tougher than you'd imagine.

Probably wouldn’t be your surgeon at that point.

use adblock and have 0 ads . if you want to support a youtuber you can use their program, they all have something

Here in Scotland, I definitely get ads. during and after Techmoan videos.

It is very quick to cure also!

I was thinking the same thing. Since all the broken parts were still inside rolling around, it would be fairly simple to match the chunks to the posts they came from and superglue them back together. Also wish he had plugged a turntable into those front jacks.

"Wide stereo" switches typically use "mid-side" processing to achieve this. Or, they "subtract" a little of each channel's output from the opposite channel. Later types would incorporate a slight delay between channels to (allegedly) enhance the effect. Personally, I've always *hated* the "wide" sound. Reminds me too much of those awful "electronically processed stereo" LPs which converted perfectly decent mono recordings into an echo-y, out of phase, unlistenable mess of a stereo image.

@caddelworth Thanks for the info, much appreciated.

a drop of fine machine oil on some moving parts on the mechanism would do some good too. I expect any grease they used would have dried out by now.

@@Andy-fd5fg Yes! I have a little bottle of watch oil that everything i work on gets a treatment of.

@@Andy-fd5fg Just be careful about the oil you use. As others here have said, some light oils (like 3-in-1) contain compounds which can "soften" some of the plastics.

THANK YOU. I can sleep now.

@@VK2XPT That’s why I marked it. It was bothering me and I was going to ask for help when it clicked for me.

Rod the knob

Ohhhh that's sweet, I was about to ask in the comments 😂❤❤ Thank youuu

Interesting!

Sounds right. Production run was 1978 to 1979.

also don't skimp on contact cleaner!

It comes down to the seller - you can tell them to send it a certain way and throw money at them, but if they choose to do otherwise they will. Been burnt many times because they see it as an opportunity to make more money.

459 at the moment 1200 likes tho

Unoriginal comment club

I presume by "hotel cards" you mean "key cards?" If so, expired bank cards or CCs also work well. That said, I did like seeing Mat use two small teaspoons for that!

@@caddelworth Yes, I meant hotel key cards. Thank you for that. For some reason, hotel key cards are thinner than CC, bank cards or even the plastic spudgers that look like guitar picks.

@@unknownpatata Interwating: the hotel keycards I've seen and used lately would all be I'd say comparable to CC thickness. This is in the UK and the Netherlands, so YMMV!