Tape Project Forum
Tape Machines => Reel to Reel Tape Machines => Topic started by: phr0gpil0t on May 22, 2009, 09:29:59 PM
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I just recently purchased a Technics RS-1700 knowing it needed work. Well I opened it up and found all of the fuses blown. I replaced al the fuses and then turned it up with a variac. But first, my theory...
My theory is that the previous owner bought the unit in Europe (it still has the European plug) and brought it back to the U.S. It was set for 220 and then he plug it into the wall. Well, I bet it didn't work too well at first. So he left it plugged into the wall, turned it around and changed the setting in the back from 220 to 110. Well, when he did this, the primary field in the transformer was turned off leaving the secondary field of the AC transformer to dissipate into the machine (like the coil in a car's ignition system). But what did he blow?
I need a schematic and few ideas from the forum. I have been reading portions of the forum for awhile but I have not had a need to post til now. Anyways, the two white wires coming from 1.25 amp fuses will continue to blow. I turned up with a Variac and the fuses blow at 30% of 120 VAC. So at roughly 36VAC on the primary side the two 1.25 amp fuses blow.
Does anybody know how badly damaged this unit is? Does anybody have schematic or a source for a schematic?
Again thanks for the help.
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Does anybody know how badly damaged this unit is?
You mean, anyone besides the guy who blew it up?
All the fuses being blown could be the result of a lightning strike to the building it was last operating in. Sounds like it could be shorted transformer windings, shorted caps, shorted rectifiers, or shorted transistors. Best bet is probably to just start checking all the stuff on the power supply board.
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Thanks for chiming in Doc. I've never worked on a Technics that was that seriously damaged but the power supply does come to mind. I don't know of any schematics/service manuals available online but if you plan on really getting into this, you should get yourself both volumes of the service manual. Having the parts list would come in handy I would think. Not only that, but you'll need to check all the adjustments and levels once you're able to get it to power up.
I think, if I were in your position, I'd check the transformer first. If that's bad, aside from having a custom replacement wound (which could be some serious $$$) it could be fatal.
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I just recently purchased a Technics RS-1700 knowing it needed work. Well I opened it up and found all of the fuses blown. I replaced al the fuses and then turned it up with a variac. But first, my theory...
My theory is that the previous owner bought the unit in Europe (it still has the European plug) and brought it back to the U.S. It was set for 220 and then he plug it into the wall. Well, I bet it didn't work too well at first. So he left it plugged into the wall, turned it around and changed the setting in the back from 220 to 110. Well, when he did this, the primary field in the transformer was turned off leaving the secondary field of the AC transformer to dissipate into the machine (like the coil in a car's ignition system). But what did he blow?
I need a schematic and few ideas from the forum. I have been reading portions of the forum for awhile but I have not had a need to post til now. Anyways, the two white wires coming from 1.25 amp fuses will continue to blow. I turned up with a Variac and the fuses blow at 30% of 120 VAC. So at roughly 36VAC on the primary side the two 1.25 amp fuses blow.
Does anybody know how badly damaged this unit is? Does anybody have schematic or a source for a schematic?
Again thanks for the help.
If none of the other fuses blow, and you increase the voltage to normal, does any part of the deck work? That is, are the 1.25A fuses the only fuses or are there more on the secondary? Or are those fuses on the transformer primary side?
It must be different than my RS-1500US schematic.
That shows a single, 2A fuse on the transformer primary, no voltage selector and then the transport has a 4A fuse and the electronics power supply has a 1A fuse. But these are after the main diodes and filter capacitors and the AC/DC switch, then the rest of the supply and associated circuitry. Isolate and test.
PM or email me regarding schematic for 1500US. I no longer have my deck.