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JVC M90 Tape deck brakes don't disengage, fwd/rwd/play all don't work


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#31 Rimmer36

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Posted 15 March 2018 - 06:25 PM

Ok straglus, thanks to you're very helpful post this might be the issue, as that slider seems to be sticking but not bent, you can lube this slider at the back of the deck. iv lubed it and im waiting for it to dry (not wd40 haha....if this works i will flipping marry you haha, fingers crossed :thumbsup:



 

what's the best way to clean off the the wd40 Norm???
 


Well, I would probably use zero residue electronics cleaner. WD40 is not a lubricant, it is a solvent and any lubrication properties will be short lived. Because it is a solvent, it is harsh and will dissolve belts, paint, and who knows what kind of damage over time to plastic & rubber, etc. If this was something more durable, I would clean it off with brake cleaner, but in this case, I’d use electronic cleaner or disassemble & clean thoroughly with soapy detergent & paint brush. In good sunny weather, the whole thing including circuit boards can be dried outside rather quickly.

 

thanks Norm you rock as ever...do you have a link to what i need my friend, i'll get some bought pronto



#32 stragulus

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Posted 15 March 2018 - 06:51 PM

Ok straglus, thanks to you're very helpful post this might be the issue, as that slider seems to be sticking but not bent, you can lube this slider at the back of the deck. iv lubed it and im waiting for it to dry (not wd40 haha....if this works i will flipping marry you haha, fingers crossed :thumbsup:


Sorry, already married, and polyamory is frowned upon in the US. Well, it's NY, nobody here would bat an eyelash tbh, but let's not go there ;) Hope it works! What lube do you use?

My deck's only fault right now is recording. I'm 99% sure this is due tot the recording pots/switches being dirty, just like every other switch/pot on this box was extremely dirty. Ex-smoker's box.. fixed all the other ones by desoldering them and given them a good vinegar bath soak, which worked *really* well. Contact spray never ever has worked well for me for more than a few weeks/months at most (using DeOxit D5).

I bought my box for really cheap, but otoh it's been on my bench for almost 3 months now (on and off, amateur hobbyist). It's that I love to fix these boxes even more than I like just owning them, but if ever you wonder why boxes in good condition are so expensive, it's the insane amount of labor that goes into them. And I haven't even recapped it or fixed all the cosmetic issues! It boggles the mind.

#33 Rimmer36

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Posted 15 March 2018 - 07:19 PM

na don't want to marry anyone to good being single and i bat for the girls haha least i did before old age haha...my victor was total scrap tbh it took me and my engineer 3 years bud and thats without a recap...but she has been working fine for the last year until now...machine oil sewing oil is good imho but you need to check with others first because there is probably much better...that bar that was sticking there was actually a head wire jammed against it, id never noticed that bar until you're post as im partially blind...but i will test her in about an hour and report back....the thing is we have put so much work into this one but at what point do you stop ehh...as you may have noticed mine was up for trade briefly  but i just can't lol



#34 Superduper

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Posted 15 March 2018 - 07:49 PM

https://www.amazon.c...r/dp/B005T8PW7O

#35 Rimmer36

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Posted 15 March 2018 - 07:54 PM

:thumbsup:  :bow:



#36 stragulus

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Posted 15 March 2018 - 07:57 PM

na don't want to marry anyone to good being single and i bat for the girls haha least i did before old age haha...my victor was total scrap tbh it took me and my engineer 3 years bud and thats without a recap...but she has been working fine for the last year until now...machine oil sewing oil is good imho but you need to check with others first because there is probably much better...that bar that was sticking there was actually a head wire jammed against it, id never noticed that bar until you're post as im partially blind...but i will test her in about an hour and report back....the thing is we have put so much work into this one but at what point do you stop ehh...as you may have noticed mine was up for trade briefly  but i just can't lol

I have a good feeling that fixed it. Glad to share the knowledge I gained here!

Meanwhile my switches/pots are soaking in a nice vinegar bath. Hopefully this will resolve my recording inputs.

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#37 Rimmer36

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Posted 15 March 2018 - 08:47 PM

It's working but we will see for how long lol.....100% it's the bar though. so im not worried now, thanks everyone, you guys rock :thumbsup:  :clap:



#38 Rimmer36

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Posted 15 March 2018 - 09:17 PM

:thumbsup:

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#39 stragulus

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Posted 15 March 2018 - 09:30 PM

machine oil sewing oil is good imho but you need to check with others first because there is probably much better...


I think here you'd use a thicker grease, e.g. superlube. Fast moving metal-on-metal seems to require a light oil such as sewing machine oil. Then there's fast moving metal against plastic which usually requires a thinner (lithium) grease, such as capstan axle end rotating in its socket. At least that's what I picked up from working on reel-to-reel decks.

#40 Rimmer36

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Posted 15 March 2018 - 09:47 PM

least i put us on the right track in the first place strangulus lol two happy campers, the victor is playing now :thumbsup:  thanks to you're post, i wouldn't have noticed but you marked it in red which i could see :lol:



#41 Superduper

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Posted 15 March 2018 - 10:37 PM

I hate to always sound so negative but everything I've learned is that acids & electronics do not mix.  So I think some care needs to be exercised here, especially when entire switches and assemblies are dunked.  Those switches are fairly well sealed when assembled (especially the record bar) and while acid may eventually eat off oxidation (depending upon how long it is soaked), it also will be extremely difficult to remove all of the acid internally unless disassembled.  So eventually, corrosion may create more problems than it solves in the short term if not all of the acid is removed.

 

It's true that oxidation on many switches cleaned with deoxit will eventually return, but that's because only the contact points were cleaned during a spray and agitation process.  The rest of the internal surfaces that remained oxidized will eventually spread again to and affect the contact points.  So the solution is to disassemble the switches and mechanically remove all of the oxidation before treating and applying with some contact preservative, such as deoxit D100, and this should provide a lasting repair.  However, this requires disassembly to do, and there is a real risk of damaging the fragile internal sliding leaf contacts in the bar shaped switches as that bar is really hard to reassemble and line up all the leafs without bending or mangling.

 

Unfortunately, I personally would not feel comfortable that I'd be able to remove all the vinegar from inside a soaked switch unless I disassembled it.  However, if disassembly is on the agenda, then there's no reason to use acid to begin with.  One last thing...  many contacts are plated.  Would an acid soak remove or damage some of the plating?  Even if you can re-soak in water for an extended period of time, since there is no flushing action internally, it just seems to me that the acid that permeated internally might be diluted at best, and diluted acid isn't as damaging as a stronger acid, but it's there and has all the time in the world.  Now, to be fair, I don't personally know, since I've no experience using vinegar, and certainly no long term experience.  As such, I'm no expert on the effect of long term consequences of using vinegar bath as a switch cleaning method.  I'm just thinking out loud.

 

One last note, from memory, the M90 does not have a record bar like most boomboxes.  I'm pretty sure the R/P switches is done electronically.



#42 stragulus

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Posted 16 March 2018 - 05:40 PM

I did take one switch apart 2 months ago, and I'm never doing that again. I'm lucky that it went back fully working. And this was a short switch, those longer ones.... brrr. These switches were *so* dirty though. I had to do something. Maybe an ultrasonic cleaner would be better? Have you managed to fix all super filthy switches with just DeOxit?

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#43 caution

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Posted 16 March 2018 - 06:05 PM

Head magnifiers make all the difference trying to work small parts.



#44 stragulus

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Posted 17 March 2018 - 01:25 PM

When I disassembled one switch, I struggled putting it back together. You have to put all the small leaf contacts back in place exactly where they need to be, or the top won't fit on and you cannot apply any pressure just in case any of them are not placed exactly right. Such a delicate process..

I've reassembled everything, works as new. I'll spray a bit of D100 in them to give them a little lubrication. Can't say anything about the longevity, other than that the switches I treated 2 months ago are still working like new as of today.

#45 Superduper

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Posted 17 March 2018 - 02:18 PM

When I disassembled one switch, I struggled putting it back together. You have to put all the small leaf contacts back in place exactly where they need to be, or the top won't fit on and you cannot apply any pressure just in case any of them are not placed exactly right. Such a delicate process..

 

Exactly, this is why I am so hesitatant to recommend disassembling the long switches.  They are so very fragile, and the longer the switch (record bar?), the more difficult and exacting the process.  On long switches, every single leaf has to be in the perfect position before reassembly or it simply won't go together, or if it does, you will likely damage the leafs.  On something like a record/playback switch where its presence is essential in order to prevent a "bricked" set, it's risky business indeed.  On the other hand, almost every such switch I disassembled had enough oxidation where the stationary posts are all black color when they should be silver.  By injecting deoxit and mechanical agitation of the switch, you will scrub off the oxidation but only on the small fine contact points.  The rest of the surfaces are still oxidized and black and it doesn't take long for it to eventually spread back to the cleaned surfaces again. 



#46 Radiola

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Posted 18 March 2018 - 01:50 PM

I love the JVC M-90 boombox. I think it is the biggest one in the world. It was sold in the middle of 80's when I was a child. I did'nt bought it, because I had'nt money of DM 998.-. 



#47 Rimmer36

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Posted 16 February 2019 - 08:14 PM

glad to confirm my victor is still going strong :thumbsup:



#48 stragulus

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Posted 14 July 2019 - 06:33 PM

glad to confirm my victor is still going strong :thumbsup:

Woot! My M90 is also still boomin'! 



#49 Rimmer36

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Posted 16 August 2019 - 09:49 PM

 

glad to confirm my victor is still going strong :thumbsup:

Woot! My M90 is also still boomin'! 

 

excellent brother :w00t:  :thumbsup: