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Quick and Dirty Restoration - Technics RS-M6 Mk2

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greenhorn

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Picked up this deck from a local dealer for 1.5K. Not in too great shape. Needed some effort to push buttons, there was hum, and the controls were worn out.

Today had some free time, so decided to take it apart, paint all the keys with silver paint, and replace the main electrolytics - including one across the motor which probably some local tech must have added.

This deck was decidedly a pain in the nether regions to dismantle - unlike most cassette decks which have the chassis at the bottom, the PCB bolted on it, and a lid on top, this was one weird integrated body, with the PCB , Transport and display bolted onto its bottom and front respectively, and the whole thing needed to be dismantled for any replacements.

Some before and after shots.

the grease in the transport along with the dust had totally solidified. had to be removed with thinner (IPA didnt work) and reapplied grease. There was a hum when play was engaged, and while playing. Replacing the caps seem to have made a world of good to the sound.

Spray painted the switches with bosny silver spray paint. Doesn't look stock, but better than the beat up look it had.

This cap seems to have been added by a local tech. compare the sizes of the older 16V 470uF and new 25V 470uF cap. Both are keltron.

For now, this is going to be my daily driver cassette deck :)







 

gopib

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Good job. I admire your courage to dive into this. I can imagine how grimy it must have been. Gives me the courage to get into a grimy piece I have with me. :clapping:
 

greenhorn

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if you are going to open up the transport, be careful with the sliding head assembly. they are usually mounted on ball bearings, and they can get lost. to keep an eye out for them.
If you dont have a manual, take pictures before you dismantle anything so that you can use them as a reference for putting it back together, and have a system to remember what screws go back where

Good luck!
 

linuxguru

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Nice work - I always wanted one of the late-'70s Technics decks with the VU meters. I finally picked up one of the last North American Technics dual-cassette decks in the early 2000s - and never played it even once. I'll need to check all the rubber rollers, belts, etc. before powering it up eventually.
 

greenhorn

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This one is utterly unremarkable. the transport has more in common with my dad's panasonic cassette player than my decks. The flywheel is smaller, and the motor/flywheel does not start until play is pressed, so the audio starts with the transient caused by the flywheel coming up to speed. But right now that's the reason I use it more, because I can leave it on at night or morning without worrying about any wear and tear - my other decks, the motor driving the pinch roller and flywheel is running full time.
 

jawedsoft

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aaah...must be some co-incidence !...while out on lunch today..I chanced upon a deck very similar to this being sold at the road side.....I don't remember the model..but it looked just like this...

the kabadiwala quoted Rs. 350 first...and then I fiddled around with the buttons and did not say anything...he has given the final offer for Rs. 200.

I am assuming that most of the things are not working in it..I still am going to get it when I return from office today..let me try my luck...who knows?

Jawed
 

greenhorn

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Today I swapped almost all the big electrolytics. Yes the originals were elna and the replacements were keltron, but they seem to have fixed the hum. Three remaining as I hadn't bought a 100u 25V and 47u caps.

Also I noticed that the motor winding seems to have been rewired. Initially, it seems the motor was wired to rotate full time, and the muting switch was connected to the muting supply. Right now the muting switch is connected in series with the motor and the motor supply, and the muting switch terminals on the amp PCB are shorted using a piece of wire.

If i wire it correctly, It should fix the weird transient start it has right now, and the background hiss when a tape is not playing - since muting is disabled, the tape preamp works full time.

But then the motor would be running full time - I like the fact that the motor gets turned off when not in use - so I can leave this deck on all the time without worrying about wear and tear.

Decisions decisions.


Will swapping the smaller electrolytics help SQ?
 

sarith

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Will swapping the smaller electrolytics help SQ?
I think it's better to leave them intact if they aren't showing signs of wear (bulge etc). Elna is better than our Keltron electrolytic caps. I managed to collect few unused Rubycon, Nichicon and Elna(used, from Sony/Blaupunkt car cd unit) caps. But if you get your hands on Elna standard caps, swap them. I have heard that after years of use caps tends to get kind of 'saturated'.
 

Vinod.R

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It is a unique deck. Sansui D-77R. Perfect working condition. I am based in Thrissur. Price I have not decided. Where are you from?
 

spanchal

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Hello
I have similar technics M6 mk2 deck unused for long time. Today i have cleaned internal dust with paint brush and tape mechanism , cleaned PCB tape deck worked fine, But LEFT channel is sounding louder then RIGHT channel sometimes sounded like cracking noise. kindly help
 

greenhorn

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There is a pot that sets channel gain. Have they been cleaned? Also record switch
 

spanchal

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Today I cleaned and adjusted channel gain pots after following things happened
1. after playing cassette for 10 to 12 min sound comes and goes between 2/3 times for 2 seconds and then follows continuous playback but there is difference in left and right channel sound, sometimes left channel sounding bit louder then right channel for +/-2db and vice versa
2 .after switching on deck humming sound appears
 

greenhorn

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I have the humming sound too - I did a full recap of the deck and still have a minor persistent hum. Still haven't been able to figure out why
1097076_708001169215538_2144916544_o.jpg
Have you cleaned the record switch too ? It's the black horizontal switch in the middle of the board - Hope you are using correct contact cleaner and not WD40.
If its not the Switch, then you may have bad transistors - the preamp in mine had 2SC1312 (though service manual had other devices) which are known to cause this - if you can confirm this (and only if you do) you will need to replace them with KSC1845FTA
 
Last edited:

Hiten

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Today I cleaned and adjusted channel gain pots after following things happened
1. after playing cassette for 10 to 12 min sound comes and goes between 2/3 times for 2 seconds and then follows continuous playback but there is difference in left and right channel sound, sometimes left channel sounding bit louder then right channel for +/-2db and vice versa
2 .after switching on deck humming sound appears
Your Balance or Volume potentiometer may be intermittent. Or may need cleaning. Humming can be caused by lots of thing. Basic first check is Shileded core of the wire coming from Playback head is ok or not. And if it is passing through some power supply cable or transformers etc.
Do update if problem is solved.
Regards.
 
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