Acquired a Technics 1200 MK2 that won't turn on. I took the platter and plastic cover off to take a look. Right away noticed there was what I assume to be magic juice residue in the well that that the power transformer sits in. No external evidence of liquid spill or anything of the like.
I plugged in to see if I could do some basic testing as far as I might understand. I measured where the power cable leads plug in and got 120V AC, then again the two red wires that run into the transformer case. Again got 120V AC. Then measured the two yellow wires that plug into the mainboard, got 0V AC. Would this indicate a dead transformer?
Just want to be somewhat sure before I go ahead with an order for a replacement transformer assembly, which comes with power cord, power input board, and transformer..
I plugged in to see if I could do some basic testing as far as I might understand. I measured where the power cable leads plug in and got 120V AC, then again the two red wires that run into the transformer case. Again got 120V AC. Then measured the two yellow wires that plug into the mainboard, got 0V AC. Would this indicate a dead transformer?
Just want to be somewhat sure before I go ahead with an order for a replacement transformer assembly, which comes with power cord, power input board, and transformer..
Just tried this. No change, still getting 0V AC across the two yellow wires disconnected from PCB. Verified 120V across the red wire terminals going into transformer. Verified that flipping the power switch on makes that live, switch off and those go to 0 as well. So don't think it's a bad switch.
There is no fuse in the USA 120V version. Connect 30VAC to the output of the transformer to see if no other parts of the circuit are damaged.
Preferably with a variac.
But disconnect the yellow wires first in case the secundary is shorted.
Hugo
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Tried this. Getting a reading of 4ohms across the two yellow wires.
I should mention I'm not getting exactly 0V AC across these. When the unit is switched on it's at 0 then slowly builds to something like 0.014V.
Unfortunately don't have a variac. Thought it odd there were no fuses on the power input board.
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Try to measure the primary with Ohmmeter (across red wires). If theres no mains fuse there might be thermal fuse inside transformer that burned out, giving open circuit.
Very small voltage across yellow wires might be stray-capacitance coupling between windings. Or just some AC hum picked by multimeter leads.
Very small voltage across yellow wires might be stray-capacitance coupling between windings. Or just some AC hum picked by multimeter leads.
Multimeter shows OL reading across the two wires. I had unwound them from the power input pcb.
Ok, thanks for confirming. Doesn't seem terribly complicated to swap.
Any tips on which of the two below might be the better option? They both cost about the same. One includes a new power input board, the other is just a transformer.
https://www.ebay.com/itm/256174177665?hash=item3ba52bbd81:g:lvoAAOSwu2dgNkn1
https://eav.com.au/shop/eav-sl12240-240v-power-transformer-technics-sl1200/
That seems to be about the going rate. Do you know where I might be able to source one?
https://uk.rs-online.com/web/p/toro...hId=299603e1-df04-42dc-af91-9dd4c3e65aad&gb=s
£25 from RS.
Look at the photo on the fleabay listing.
You will need to wire it and fix it, then you will have a working machine.
£25 from RS.
Look at the photo on the fleabay listing.
You will need to wire it and fix it, then you will have a working machine.
Have quite a bit of discomfort with wiring transformers!! Let me see if I can find anything else and if not might look at going down this way.
Thanks Hugo! Was trying to make that out from the dead transformer but some wiring and glue over some of the letters.
Hi Everyone,
Got a used matching transformer/ac cord/power-switch assembly. Would like to say it was for the sake of "keeping it stock", was some of that, and some anxiety with wiring another transformer. As is, this was a fairly straightforward drop in. Got 30V AC coming out of it. Hums a small bit, will take it. Turntable turned on fine. Put it all back together, put in my system. Got sound out of the left channel, nothing out of the right. It had aftermarket phono wires installed when I picked it up. They are a bit thick for this purpose, connectors not very good. Will test continuity soon to isolate where signal is breaking down, but thinking to swap the wires in any case.
Cheers to all who helped me along!
pic above shows secondaries not yet wound up around posts, I didn't forget that bit before putting it back together
.
Got a used matching transformer/ac cord/power-switch assembly. Would like to say it was for the sake of "keeping it stock", was some of that, and some anxiety with wiring another transformer. As is, this was a fairly straightforward drop in. Got 30V AC coming out of it. Hums a small bit, will take it. Turntable turned on fine. Put it all back together, put in my system. Got sound out of the left channel, nothing out of the right. It had aftermarket phono wires installed when I picked it up. They are a bit thick for this purpose, connectors not very good. Will test continuity soon to isolate where signal is breaking down, but thinking to swap the wires in any case.
Cheers to all who helped me along!
pic above shows secondaries not yet wound up around posts, I didn't forget that bit before putting it back together
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One common problem is dirt on the contacts in the headshell socket. If they are not 'too-far-gone' I gently clean them with a glass pencil.
I haven't encountered one single aftermarket phono wire being better than the originals. That's not to say they don't exist. And many times it turned out the owner did a real sloppy job. People tend to think that thicker is better.
The best original wires were IMO the very old ones for they had the lowest capacitance.
If the RCA plugs need changing, I use Rean NYS373 or Neutrik NF2C-B/2.
Hugo
Hi Hugo,
Thanks for the tip on the glass pens, going to pick one of those up!
Kabusa seems to recommend a specific Mogami wire for wire replacement. Thinking I will use that. In this case it looks like this unit was serviced at a now defunct stereo shop, where they used Adcom RCA cables for the job. The same as the set in this listing.
I'm not sure if I will keep this table. I picked it up for a good price because it did not power on. It's a black MK2 model. I would like to get a matching one, but those in US market are expensive. I might sell this and use funds to buy two of Japanese 1200 MK3 models, either use a step up transformer or do internal transformer swaps in them. Was not difficult to install a new transformer.
I have used those NF2C's before, they're nice if you don't plan on disconnecting the equipment anytime soon. Very tight fit!
Make your own wires using coaxial cable.
Many fancy wires are over priced junk, some in India have open shielding connections!.
A 50 VA transformer would have been enough, about $5 here for a single primary / 2 secondary winding type, custom made, may be higher now as copper prices have gone up.
And for the sake of mental peace, change all the electrolytic caps in the supply, as the unit seems more than 10 years old.
Many fancy wires are over priced junk, some in India have open shielding connections!.
A 50 VA transformer would have been enough, about $5 here for a single primary / 2 secondary winding type, custom made, may be higher now as copper prices have gone up.
And for the sake of mental peace, change all the electrolytic caps in the supply, as the unit seems more than 10 years old.
Will do some reading on this, not sure how necessary it is. Don't want to go looking for trouble.
Technics 1200 parts have gone up quite a bit!