Hi guys!
So I’d like to surprise my mom and fix her old stereo which she no longer uses, due to it being making all sort of crackling noises, and no longer having a very large LPs collection. It was a nice one and she’s fond of it. It’s an old Scott 440A, and it has hooked both an LP player and a radio. It did have a tape player recorder, but I think that eventually got broken and thrown out. My solution would need two steps:
-I need to clean the amp potentiometers, specially the volume one, makes really loud cracks when moved. I have no idea how to do this! Is there any guide or youtube video showing how to do it?
-I’d like to buy a bluetooth DAC/CD player combo, so she can turn the AUX input and use it to play either CDs or music from the phone or the laptop in the bluetooth mode. She does have a cheap CD player connected to it, and I hooked also a cheap bluetooth DAC to the CD player external input, but the whole thing is a mess. She needs to remember to go aux, then choose the external input in the CD, then turn on the crappy USB bluetooth dongle thingy. I’d like a better looking single unit that does both BT and CD if needed. Is there such thing? Any recommendations?
Thanks a lot!
On a high level, you can get a cleaner like Deoxit D5 in a spray bottle. Most pots have a slit in them so you can spray into them, then turn the pot through its range a bunch of times. It’s worth a try as a start. Obviously do it while the unit is unplugged.
If you want to consider a more aggressive rebuild, like a capacitor replacement, maybe find a cheap old amplifier at the thrift shop to use as practice for desoldering/resoldering.
You might be able to connect the BT to one input on the amp, like the tape input, and the CD to another.
Thanks, i think I’ll get deoxit definitely, I’ve seen it recommended everywhere.
Regarding the dac…there is only one left. Phono and radio are taken. So only aux was left… That’s why I’m trying to go for something covering both. If not possible, could you recommend a good BT DAC?
Does it make crackling noise while turning the volume potentiometer?
Yup it does. Very sharp and usually much louder than the actual playback volume.
Just replace the potentiometer, they get rusty. I had the same problem restoring my grandmas old amp.
Is there a guide to do this? That’s what I’m trying to figure out, what steps I’d need to do to clean it or even replace it.
In addition to the caps and pots, have you checked the condition of the power cord? Depending on age/storage condition it might need replacing if it has become cracked or stiff.
I think it was a C13 generic socket in the rear, so any cable could connect. Really, the only thing giving trouble seemed to be the volume.
It’s going to be more work than you think. An old stereo like that is also going to need new capacitors. (Worn capacitors can also cause many issues.) So, you’ll need soldering skill.
First, you’ll want to look up the service manual. That’ll tell you about the various parts and components inside.
Cleaning potentiometers isn’t hard. But if one or more of them is deteriorating from wear - not just dirty - they’ll need to be replaced, and that also requires soldering.
An old stereo like that is also going to need new capacitors.
This. As capacitors dielectic fluids deteriorate over time.
With Shematics in hand, open up that stereo system. With a thin plastic/dry wooden stick (thickness of straw), gently knock on all caps while stereo is playing. You will find the culprit cap(s).
It is recommended that you replace all electrolytic capacitors, but more time and energy. Throw it on “future projects” basket.
Caution:
⚠️ Risk of electric shock ⚠️
****** BE CAREFUL *******
- wear shoes (utility boots, eg. CAT boots)
- wear gloves (a dry-cloth glove at least on hand that will hold the stick)
- put the stereo unit on a table where you can stand while you test it. Make sure there’s nothing behind you, in case you need to abruptly fall down. 'Cause accidents happen.
- bonus: have plastic lamina paper cover areas where grid power gets stepped down to prevent accidental touch. 'cause, for most well-made devices, grid power is handled on a separate PCB board. You will clearly see it (huge capacitors and a big fat transformer)
Thanks! I guess I can try to clean them first. The amp does turn on, and as long as I’m not changing the volume, it does play back correctly. If things continue to deteriorate, I’ll consider a fix.
There’s a lot here. I agree it’s not just as simple as cleaning a pot. A service tech is really the best way to get this done correctly. That’s not a cheap fix either depending on all the issues. You can at least find out what it would take to get it to working order though.
