SX-1010 Transformer Dead?

tsd71

RIP Tom Petty
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Just got in a 1010 the previous owner told me the transformer was shot, when I opened the bottom all looked good except for the 6AMP fuse encased in a roll of clear plastic. It was toast and burned the inside of the plastic too, must have been hot in there. OK so I replaced with another 6AMP straight to dim bulb and super bright light, no sound from the unit at all, no transformer buzz, no electrical sound, no lights, no nothing. How do I test for a bad transformer, never had one before. I do not see any obvious failures on the power supply or the amp boards, I will check the outputs when I figure out if the transformer is bad or not.

Thanks:thmbsp:
 
Outputs are all good

Tsd71,

Post the voltages off of the power supply board, the one on the bottom side. Also look for cracks in that board as it sits very, very close to the bottom cover. From my memory the transformer is the least likely part that has failed.
 
Are any of the fuses on the fuse board AWR-053 blown? If not, it's probably the big rectifier and large cap circuit; something shorted (Bad). Are the big filter caps original? The originals are solder terminal and a pain to deal with. Only saying; and wondering about isolating it. The whole thing is wire wrapped. The amp boards could be shorted too. :scratch2:
Any regulated (+-) voltage when on the DBT?
Transformer: Low probability.

Thinking out loud. :D
 
try pulling the internal fuses then see if it powers up with a dim or bright bulb ..
if dim thats a good sign ..
if bright still pull the rectifier diodes ...the ones that are wired straight to the transformer and try again ...bright bulb then = shorted transformer ...or a trapped wire maybe ..
first though if you put your ohm meter across the primary windings to see if its short ..
also check if shorted primary to secondary
 
Pop all the fuses out except the line fuse and try with the DBT. This will eliminate everything except the transformer, large 18K PS caps, and the large PS rectifiers. (But a major short in the power amp can still pop the fuse, or in this case cause the DBT to glow brightly. Remember, a simple diode test catches about 60~70% or so of transistor failures at best.)

The main PS rectifier is on the fuse board. Two pieces, each having two diodes. One with a common anode, and one with a common cathode. I've never seen one go bad, but anything is possible.
 
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pulled all fuses and still getting very bright light. Filter caps are newer, checked all diodes on both amps all are good, all diodes on power supply are also good. Pull the two big u shaped rectifier diodes on the fuse board?
 
Pop all the fuses out except the line fuse and try with the DBT. This will eliminate everything except the transformer, large 18K PS caps, and the large PS rectifiers. (But a major short in the power amp can still pop the fuse, or in this case cause the DBT to glow brightly. Remember, a simple diode test catches about 60~70% or so of transistor failures at best.)

The main PS rectifier is on the fuse board. Two pieces, each having two diodes. One with a common anode, and one with a common cathode. I've never seen one go bad, but anything is possible.

How do you test those PS rectifiers?
 
Diode function- look at the diagram of a full wave rectifier- what you have is a full wave split in two- one U has a common anode and one U has common cathode. The metal U depending on which one it is will serve as the common point, the two other points will be the test point to either the cathode or anode.
 
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Disconnect the unfused transformer wires, the two red wires going to the awr-063 board pins 1 and 2, as well as being sure that all fuses BUT the power line fuse have been removed.

What MODEL is this? KCU? A single voltage unit?
 
Mark, disconnected pins 1 & 2, left in F1,I'm assuming F1 is the power line fuse, all other fuses removed. Powered up on dim bulb, bulb does nothing(very dim, dark), lights come on the front panel, and it sounds like the transformer is running. Yes it is a single voltage unit.
 
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Just checked both rectifiers on AWR-063 and they appear good on a diode test. Did I insert the fuse in the right location F1?
 
if f1 is the main fuse ..nothing happens without it ..
with the unit unplugged from mains first check voltage on main filter caps it has to be zero volts for this . then set your meter on ohms 200 ohms or lower then measure resistance of caps .if the reading creeps up and up then the caps are maybe fine .if they stay shorted you need to disconnect them and test again .
 
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pulled all fuses and still getting very bright light. Filter caps are newer, checked all diodes on both amps all are good, all diodes on power supply are also good. Pull the two big u shaped rectifier diodes on the fuse board?

Newer filter capacitors - wired correctly - or one back to front perhaps?
 
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It's actually just the main 3.15 amp fuse that you need installed. The one on the back of the set. The big 6 amp is in line (series) but that is not referenced. I think its for the switched outlet protection (It needs to be a good fuse as well). F1 (Rated at 2.15 amps) is located on the main fuse board and protects the AC panel lighting. The righteous print that I have is very small and I have to use my multiplier headset to even get close to seeing the print. Does any have a large high res print of the sx-1010 to purchase?
 
Zeb; Wheni did mine, I blew up each individual board schematics to full page size, and mounted them on a corkboard overlaid on top of the blown up (multiple page) "hi res" complete schematic which was fuzzy. There's enough resolution on the individual board schematics you shouldn't need the magnifier. Use the 45 mb "HI-RES" version here
 
Newer filter capacitors - wired correctly - or one back to front perhaps?

I compared the filter caps to my working 1010 and it appears they are installed properly.
I have attached a few pictures.
 

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