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Hi-Fi Technics SL-1200 MK2 repair.

 
Boingy
(@boingy)
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Posts: 137

Hello all,
After many years of inactivity, I dusted off my 1200's that I used to use when DJing out on the road.
I was wondering if the group would be interested in hearing about the repairs and modifications?
Technical data is not an issue as I still have the original paper manual 🙂
What say ye?
All the best,
Tony

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Topic starter Posted : 17/03/2021 1:47 am
PYE625, Lloyd, Nuvistor and 4 people liked
crustytv
(@crustytv)
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@boingy

Go for it Tony, it'll be a pleasant change for folk👍 

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Posted : 17/03/2021 8:46 am
Cathovisor
(@cathovisor)
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Yep, I'd certainly be interested to hear about it! 

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Posted : 17/03/2021 1:28 pm
Marconi_MPT4
(@marconi_mpt4)
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I certainly would also be interested as these were rare visitors to the workshop.

Rich

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Posted : 17/03/2021 2:54 pm
PYE625
(@pye625)
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Agreed.... it would be an interesting read.

I use an SL1800 deck.....

IMG 5866 50

 

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Posted : 17/03/2021 10:38 pm
Doz
 Doz
(@doz)
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@boingy Funnily enough, I've just repaired the most seized up VTA adjustment I've ever seen on one of these for a friend. Easy deck to work on...

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Posted : 18/03/2021 11:23 am
Boingy
(@boingy)
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Posts: 137

Hello all,
Looks like I'd better get started 🙂
So after probably 20 years stored away in various facilities and garages, I opened one of my flight cases and there was a bit of green mouldy dust, which was taken care of with a vacuum cleaner, some diluted bleach and a rag to dry off.
The most common problems I used to find were the stylus lamp blowing, the pitch control getting erratic, the phono leads failing and the mains transformers buzzing.
Now I changed my phono leads yonks ago for something far more robust, so they're OK.
Time has taken it's toll on the transformer, however which now audibly buzzes and is especially noticable when the stylus is placed on a still record.
The special lamp is blown.... Quelle surprise!
Oh, and the pitch control centre detent contacts are erratically losing connection, so frequency lock comes and goes. The pitch control slider has a centre detent with shorting contacts that tells the control IC to only listen to it's own fixed quartz controlled oscillator, instead of the variable RC oscillator. One of the bugbears for many DJ's was that the speed would quartz lock a little before (and after) the centre detent was reached. This hysterisis would mean that beatmatching would be impossible in some cases, unless the other deck's pitch control was moved also. This I found out many times for myself on gigs!
Nowadays there are versions of the pitch control where the contacts are much more tightly aligned to the detent. Indeed, later versions of the SL-1200 had specific "Reset" switches to quartz lock to 33 or 45 RPM and pitch sliders with no detents.
The bearings could do with a bit cleaning and lubrication as well.

So the list on this 1st deck goes something like this :-
Build external power supply.
Fit new lamp.
Fit new pitch control and set up centre frequency and pitch gain to get +-8% pitch swing..... Harder than the manual says, by the way!
Clean and relubricate bearings.
Fit original platter mats and upgrade cartridges.

BTW my decks were retrofitted with "Beatkeeper" interfaces that plugged into a box that gave a digital readout of two decks' pitch settings/BPM values. The system was a forerunner of what is commonplace now on mixing CD, HDD and software players.
I wish I could remember what the system was called..... It was absolutely brilliant at setting up decks consistently!

Anyway, I'll get to work...... @Doz, I'll have to see how the VTA will work out on this deck. It hasn't been changed for maybe 25 years!

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Topic starter Posted : 19/03/2021 1:12 am
Alex728 liked
Boingy
(@boingy)
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@pye625 I haven't seen one of those for ages.... Hope it gets plenty of use 🙂

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Topic starter Posted : 19/03/2021 1:15 am