SA-500A worth saving?
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39cross
Well-Known Member
The SA-500A is a capacitor coupled amp of an older design, puts out about 11 wpc. It's nice but not particularly valuable. Me, I think they are kind of cool. It would be fun to restore as a project, don't expect the ultimate in sound, but do expect it to be a competent early 70's Pioneer design. You have to judge it by it's era, and these were not cheaply built despite being low-powered by later standards..
One way to learn more about these pieces we buy/trade/repair/sell/etc is to learn on something like this. Value is low, but figuring out how to recap and repair and trace down a problem, is a cheap learning experience.
You might fix it, you might not, but you aren't investing a boatload of dollars either, so value is what you get out of it!!
You might fix it, you might not, but you aren't investing a boatload of dollars either, so value is what you get out of it!!
Rob DeFries
Active Member
Maybe I can pump some new life to this question. I think this is amp is getting more and more sought after. Where I could buy them for 10-20 Euro's a couple of years ago, now the fetch up to €100 and more.
Just because the gold coloured knobs plates dropped off, people lost the speaker plugs and such, a complete one is hard to find, almost impossible if you want all 4 the speaker plugs.
If the amp has had a total recap and maybe some new transistors in the phono (head) amp or control amp, it can sound really nice and detailed. As said, it's simple, easy to fix and teamed with the TX-500A it sure is a good looker and a good point of conversation.
I predict this one is a sleeper. It'll be harder to pick one up, scarse will make desired.
I think all the x00's from the early 70's are the ones to keep an eye on.
Even as a repair trainer, it'll give you more ideas and know how about electronics.
And yes, a 10,000uF/50V fits perfect in the 3300u holder. Swap the rectifying diodes for something like 4007's or fast recovering ones. It's a rewarding job to upgrade this little darling!
The control board hasn't been touched yet.
Yes. Sanyo 2.2uF..... alarm. Leaking. Reading on the meter was good! But it didn't work. 4.3 volts on pin 4 (yellow wire). Hiss and crackling from the transistors too!
Just because the gold coloured knobs plates dropped off, people lost the speaker plugs and such, a complete one is hard to find, almost impossible if you want all 4 the speaker plugs.
If the amp has had a total recap and maybe some new transistors in the phono (head) amp or control amp, it can sound really nice and detailed. As said, it's simple, easy to fix and teamed with the TX-500A it sure is a good looker and a good point of conversation.
I predict this one is a sleeper. It'll be harder to pick one up, scarse will make desired.
I think all the x00's from the early 70's are the ones to keep an eye on.
Even as a repair trainer, it'll give you more ideas and know how about electronics.
And yes, a 10,000uF/50V fits perfect in the 3300u holder. Swap the rectifying diodes for something like 4007's or fast recovering ones. It's a rewarding job to upgrade this little darling!
The control board hasn't been touched yet.
Yes. Sanyo 2.2uF..... alarm. Leaking. Reading on the meter was good! But it didn't work. 4.3 volts on pin 4 (yellow wire). Hiss and crackling from the transistors too!
Rob DeFries
Active Member
QSilver
Super Member
I had also got one in for restoration a while after making this post. Mine luckily came with all the metal fronts on the knobs - just needed gluing back on. After cleaning and a re-cap etc it does sound really really good. Nice and small and good sound. I replaced the pilot light with an LED too as the bulb holder disintegrated. I upgraded the filter cap a little but not as high as 10,000. I think I picked mine up for around £30.... its sitting on my shelf at the moment.
Good sound and nice smooth controls.
Good sound and nice smooth controls.
Rob DeFries
Active Member
The last one (this one) I bought was € 45.
Complete with all the knobs and 2 speaker plugs.
This was my first try with a big cap. I used 4700 uF before, which I could fit under the chassis, leaving the 3300 in place.
I do think the 10,000uF is a bit over the top. Pricewise it's not much more expensive then the 4700.
Complete with all the knobs and 2 speaker plugs.
This was my first try with a big cap. I used 4700 uF before, which I could fit under the chassis, leaving the 3300 in place.
I do think the 10,000uF is a bit over the top. Pricewise it's not much more expensive then the 4700.
Rob DeFries
Active Member
Maybe I do it on one that I want to keep. I have one without the special plugs and only one complete knob. That would be a good one to upgrade the **** out of it.
I sell them, once in a while, so I'd rather have it original. With big black plugs.
I sell them, once in a while, so I'd rather have it original. With big black plugs.
It's an old thread but for a friend I an giving the SA-500A a bit attention.
I replaced some caps in the power circuit replaced the diodes.
It was suffering severe humming which is less now but still you can hear it. Is this a common issue of the amp?
Or which caps should I replace to get it more quiet. Caps still measuring 'new'.
Thanks in advance.
I replaced some caps in the power circuit replaced the diodes.
It was suffering severe humming which is less now but still you can hear it. Is this a common issue of the amp?
Or which caps should I replace to get it more quiet. Caps still measuring 'new'.
Thanks in advance.
QSilver
Super Member
Hum in amplifiers is usually caused by the rectified AC ripple getting into the audio path. The first thing to check before replacing capacitors etc are ground connections to and from the chassis. A single bad ground can cause hum.
Next would be a failed voltage regulator of sorts that is no longer regulating and so allowing the AC ripple to get through and impressing that sound onto the amplifier.
1. Check all the ground connections.
2. Get the schematic and check the power supply voltages both DC and AC - an AC reading on a DC signal will indicate excessive ripple and a possible regulator failure.
Also, I see you're going through a lot of old SA-500A threads asking questions about your hum problem. Best bet is to create a brand new thread for your problem - there's some great troubleshooters around here that are bound to chime in and help. Way better than digging up an old thread!
Next would be a failed voltage regulator of sorts that is no longer regulating and so allowing the AC ripple to get through and impressing that sound onto the amplifier.
1. Check all the ground connections.
2. Get the schematic and check the power supply voltages both DC and AC - an AC reading on a DC signal will indicate excessive ripple and a possible regulator failure.
Also, I see you're going through a lot of old SA-500A threads asking questions about your hum problem. Best bet is to create a brand new thread for your problem - there's some great troubleshooters around here that are bound to chime in and help. Way better than digging up an old thread!
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