Silver sa-5030
- Thread starter Alfonsol
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asoundhound
Definitely Low-fi
just the model number with no brand name makes it nearly impossible to give you any input, but at 10 bucks, you don't have a lot to lose.
the brand is silver. here is a pic.
this brand was quite common in the early 80's here im chile, but i never listened to one. i remember they have a good reputation .
in this links there are a few specs
http://www.hifigoteborg.se/Silver sa-5030 spec.htm
Surfing the internet i discovered it was made by Shin Shirasuna Electric Corp. a japanese company that also made some stuff for harman-kardon
this brand was quite common in the early 80's here im chile, but i never listened to one. i remember they have a good reputation .
in this links there are a few specs
http://www.hifigoteborg.se/Silver sa-5030 spec.htm
Surfing the internet i discovered it was made by Shin Shirasuna Electric Corp. a japanese company that also made some stuff for harman-kardon
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asoundhound
Definitely Low-fi
looks like a very respectable unit. i would say 10 bucks is a steal.
Today arrived the amplifier, soon i will post some pics.
it's very dirty inside and outside. the fuses are good and no traces of heat.
don't powered up yet
by simple inspection i discovered some cold solder joints.
now i'm cleaning it.
it seems like the output transistors of one channel have been changed
it have a large toroidal transformer inside.
the inputs are din, but someone added an rca input.
it have connectors for 2 pair of speakers. 4 8 or 16 ohms.
the seller says no sound, but the led powers up.
any precautions when i try to power it up?
it's very dirty inside and outside. the fuses are good and no traces of heat.
don't powered up yet
by simple inspection i discovered some cold solder joints.
now i'm cleaning it.
it seems like the output transistors of one channel have been changed
it have a large toroidal transformer inside.
the inputs are din, but someone added an rca input.
it have connectors for 2 pair of speakers. 4 8 or 16 ohms.
the seller says no sound, but the led powers up.
any precautions when i try to power it up?
After cleaning it a bit, i discovered lots of cold solder joints. the board is a mess, somemone changed almost all the components in one channel, but didn't know how to solder properly.
there are no signs of heat, nothing burned. also there are no sign of bulging or leaking caps. i didn't try to power it up yet. saturday i will repair the cold solder joints, and i wil try to power it up.
there are no signs of heat, nothing burned. also there are no sign of bulging or leaking caps. i didn't try to power it up yet. saturday i will repair the cold solder joints, and i wil try to power it up.
i made a quick cleaning and repaired some cold solder joints. i tried to power it up and... nothing happens.
with my dmm i checked continuity in the power cord, the transformer, fuse and power switch. i discovered a cold solder in the rectifier.
the transformer measures 8 ohms in the primary and 1.4 ohms in the secondary. i don't know if this readings are fine or not, and my multimeter is not very accurate in this range.
with my dmm i checked continuity in the power cord, the transformer, fuse and power switch. i discovered a cold solder in the rectifier.
the transformer measures 8 ohms in the primary and 1.4 ohms in the secondary. i don't know if this readings are fine or not, and my multimeter is not very accurate in this range.
asoundhound
Definitely Low-fi
i think i'd try to restore the repaired channel. whoever tinkered probably didn't know what they were doing. the bad soldering is a giveaway. if the un-molested channel is good, try to copy it.
asoundhound
Definitely Low-fi
good luck!
i dissasembled all the boards, and cleaned all. i discovered a really bad solder in the negative rail of the power supply. i resoldered it, assembled the unit, and turned it on.
no smoke, nothing hot, the fuses are ok and the power led is on.
i didn't tried yet to connect speakers, when i have time i will measure dc offset.
no smoke, nothing hot, the fuses are ok and the power led is on.
i didn't tried yet to connect speakers, when i have time i will measure dc offset.
i measured dc offset.
when i first turn it on it reads 0 on both channels ( it doesn't have a relay, but a n overload proteccion circuit) after 6 seconds the voltage starts to jump, 30 mv, 0v, 40 mv, 0v 500 mv, 0v..... after 15 seconds it stabilizes in 30 mv left channel, and 540 mv right channel. after a while sometimes the left chanel sometimes drops to 0, and the starts to jump again, and then stabilizes.
how bad are these readings?
what i should do now?
when i first turn it on it reads 0 on both channels ( it doesn't have a relay, but a n overload proteccion circuit) after 6 seconds the voltage starts to jump, 30 mv, 0v, 40 mv, 0v 500 mv, 0v..... after 15 seconds it stabilizes in 30 mv left channel, and 540 mv right channel. after a while sometimes the left chanel sometimes drops to 0, and the starts to jump again, and then stabilizes.
how bad are these readings?
what i should do now?
thefragger
Certified Crazy.
If you move the amp while the DMM is hooked up does the DC offset change?
Try testing continuity in the transistors. I can't remember off the top of my head how, but the information's on the site somewhere.
BEST of luck! I love fixing old gear, it's like solving a puzzle!
Philip.
...
Try testing continuity in the transistors. I can't remember off the top of my head how, but the information's on the site somewhere.
BEST of luck! I love fixing old gear, it's like solving a puzzle!
Philip.
...
lookiin for bad solders i discovered a missing resistor in the channel that have a offset of 540 mv. the missing resistor is the r445.
also when i was looking for bad solders accidentaly i shorted two leads of the q 423 and i got a big spark(the ones that are not connected to r445). if i measure resistance between these points i got negative reistance. the unit was unplugge, so i think the main filter caps discharged from the +rail trough the resistor 441 and the base of q425 to the -rail. i hope not dameged anything.
also when i was looking for bad solders accidentaly i shorted two leads of the q 423 and i got a big spark(the ones that are not connected to r445). if i measure resistance between these points i got negative reistance. the unit was unplugge, so i think the main filter caps discharged from the +rail trough the resistor 441 and the base of q425 to the -rail. i hope not dameged anything.
