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#1
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Toshiba sa-500 receiver
I was recommended to go here by rusty . I am new to vintage audio,
and recently got a toshiba sa-500. It has a pretty bad balance issue. I have to turn the knob to 3 on the right for it to be balanced. Any solutions? |
#2
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Toshiba sa-500 receiver
On Tue, 8 Jul 2008 20:34:35 -0700 (PDT), carfreak
wrote: I was recommended to go here by rusty . I am new to vintage audio, and recently got a toshiba sa-500. It has a pretty bad balance issue. I have to turn the knob to 3 on the right for it to be balanced. Any solutions? snip First, swap the speaker leads and see if the trouble follows the speaker. You may have a loudspeaker issue, not an electrical issue. If the trouble doesn't follow the speaker, you could have a number of different problems, a likely one being a toasted output transistor, which would make the channel in question about 6 dB less loud than the good one. You don't say if the affected channel has a distortion problem or not, which could alos be an indicator. These weren't very good units, so don't go spending a lot of money fixing it. Toshiba's audio products were, around that time, discount store stuff at best. Their cassette decks were some of the worst I've ever seen at any price. |
#3
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Toshiba sa-500 receiver
On Jul 9, 1:22 pm, DeserTBoB wrote:
On Tue, 8 Jul 2008 20:34:35 -0700 (PDT), carfreak wrote: I was recommended to go here by rusty . I am new to vintage audio, and recently got a toshiba sa-500. It has a pretty bad balance issue. I have to turn the knob to 3 on the right for it to be balanced. Any solutions? snip First, swap the speaker leads and see if the trouble follows the speaker. You may have a loudspeaker issue, not an electrical issue. If the trouble doesn't follow the speaker, you could have a number of different problems, a likely one being a toasted output transistor, which would make the channel in question about 6 dB less loud than the good one. You don't say if the affected channel has a distortion problem or not, which could alos be an indicator. These weren't very good units, so don't go spending a lot of money fixing it. Toshiba's audio products were, around that time, discount store stuff at best. Their cassette decks were some of the worst I've ever seen at any price. we did switch the speaker leads. that was the first thing we did. the speaker was not the issue. the receiver has a lot of sentimental value to my friend it belonged to his grandparents. how hard is it to switch out the output transistor? Rusty |
#4
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Toshiba sa-500 receiver
On Wed, 9 Jul 2008 14:20:57 -0700 (PDT), Rusty
wrote: we did switch the speaker leads. that was the first thing we did. the speaker was not the issue. the receiver has a lot of sentimental value to my friend it belonged to his grandparents. how hard is it to switch out the output transistor? snip OK, this unit (I believe) has a speaker selection switch. Try running from the "B" speaker terminals and see if the problem still stays the same. Replacing a standard TO3-case output transistor is quick work, but first you have to know how to find the bad one. Tools would be a soldering iron, thermal grease and normal screwdrivers, side cutters, et al. I really don't have the JEDEC number of the original outputs on those handy, but suffice it to say that, if failed, the bad transistor won't be shorted, since the amplifier is still operating. I'd look for oxidized connections on the output transistor heat sink. Also, be aware that Japanese electronics from this era were well known for developing cracked solder on their wave-soldiered PC boards, but I don't think that's the issue here. |
#5
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Toshiba sa-500 receiver
On Jul 9, 5:14*pm, DeserTBoB wrote:
On Wed, 9 Jul 2008 14:20:57 -0700 (PDT), Rusty wrote: we did switch the speaker leads. that was the first thing we did. the speaker was not the issue. the receiver has a lot of sentimental value to my friend it belonged to his grandparents. how hard is it to switch out the output transistor? snip OK, this unit (I believe) has a speaker selection switch. *Try running from the "B" speaker terminals and see if the problem still stays the same. Replacing a standard TO3-case output transistor is quick work, but first you have to know how to find the bad one. *Tools would be a soldering iron, thermal grease and normal screwdrivers, side cutters, et al. *I really don't have the JEDEC number of the original outputs on those handy, but suffice it to say that, if failed, the bad transistor won't be shorted, since the amplifier is still operating. I'd look for oxidized connections on the output transistor heat sink. Also, be aware that Japanese electronics from this era were well known for developing cracked solder on their wave-soldiered PC boards, but I don't think that's the issue here. My receiver hasn't been used in probably over a decade, so oxidation is very possible. I will check it out, thanks for the advice. If I do find oxidation, how should I clean it? |
#6
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Toshiba sa-500 receiver
On Wed, 9 Jul 2008 21:52:35 -0700 (PDT), carfreak
wrote: My receiver hasn't been used in probably over a decade, so oxidation is very possible. I will check it out, thanks for the advice. If I do find oxidation, how should I clean it? snip On wafer switches, the best first aid is simply exercising them. For noisy switches and pots, a switch contact cleaning spray, notably those from Caig Laboratories (Caig Pro Gold is a favorite of mine), is best, but don't overdo it. Washing potentiometers and switches too much will wash out all the "pot grease" and the oxidation will return shortly, along with erratic performance. Also of concern, if the unit has been sitting around unenergized, is the condition of any electrolytic capacitors in the unit. Usually, this will manifest itself in "crackling and popping" noises, if the power supply electrolytics are bad. Most of the older Japanese receivers of this ilk used Nichicon axial electrolytics in for stage decoupling, and they do tend to go bad. Job 1 right now, though, is tracking down why one channel is performing badly. Good luck with that. |
#7
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Toshiba sa-500 receiver
My receiver hasn't been used in probably over a decade, so oxidation
is very possible. *I will check it out, thanks for the advice. *If I do find oxidation, how should I clean it?- Hide quoted text - - Show quoted text - carfreak check your email, I sent you one |
#8
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Toshiba sa-500 receiver
carfreak wrote:
I was recommended to go here by rusty . I am new to vintage audio, and recently got a toshiba sa-500. It has a pretty bad balance issue. I have to turn the knob to 3 on the right for it to be balanced. Any solutions? it sounds like that there is a problem in the signal path like a resistor that has opened up or a dried out electrolytic capacitor. i don't think it is a output stage problem. here is the best place to go to get help with your vintage Toshiba. http://audiokarma.org/forums/forumdisplay.php?f=13 -- |
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