How to replace Polystyrene/Styrene capacitors?

[Karl vd Berg]

Hi good folks from DiyAudio!

This is Karl van den Berg again. I have a nice Akai AM-U03 amp I got for free from a kind and beautiful young lady (can be better? No!) and it's has some pre-amp section REALLY bad. I see some of these (Polystyrene/Styrene) totally "black" in the Loudness and Subsonic filters boards and in fact these sections are not working. I'd like to know how can I replace them with new ones without damaging them during soldering process.

Or... if I can replace them with another type like film cap, mica, polyester, etc...

Normally they "last forever" in board if everything is OK, but when something happens, it can be tough for few people replacing them. Not sure if I'm able to be fast even with flux, so if it's possible to get same results with another capacitor types, would be really great!

Thanks ya all! 🙂

 

[DF96]

Has someone been trying to solder them with a blowtorch?

To avoid damaging polystyrene caps during soldering, just use normal competent electronic soldering techniques. Hot iron, good quality leaded solder with flux cores, don't touch the cap itself with the iron - just the leads.

 

[overtheairbroadcast]

What DF96 said. If you are worried and if you have enough space, then use a little more leg and raise them slightly off the board.

 

[jacco vermeulen]

I'd replace them by NPO/COG ceramics.

A : because the type of styrols in the Akai are junk.
B : makes zero difference, and much cheaper. Buy ten 5% SMD's : 50 cents.

(vlag op 'n modderschuit)

 

[Elvee]

Or... if I can replace them with another type like film cap, mica, polyester, etc...

Plain foil polypropylene's are the second best option, with mica and COG 3rd and 4th (or 4th and 3rd depending on the actual model).

 

[jcx]

Mica aren't in the running if you believe DA relates to audio quality - better gardes of Mylar measure better

NP0/C0G overlap polypropylene in Pease DA plots


modern lead free soder in the hands of newbies is even more potentially dangerous to polystyrene caps - while working fast helps, clamping the lead wire close to the cap body with something to sink conducted soldering heat before it melts the plastic may be needed

 

[Karl vd Berg]

Thanks, folks! Much appreciated!

 

[davidsrsb]

Polystyrene capacitors were one of the few components easily damaged by a competent solderer with 60/40 solder if the iron was the wrong size or the pcb/leads a bit tarnished. With lead free I would be very worried

 

[Karl vd Berg]

Polystyrene capacitors were one of the few components easily damaged by a competent solderer with 60/40 solder if the iron was the wrong size or the pcb/leads a bit tarnished. With lead free I would be very worried

Yeah, I know. That's why I'd like to avoid/replace them with something else.

I have good tools (iron soldering station, 60/40 solder, flux, etc) and although these caps have very low tolerance and stability, etc, they are a pain in the way.

 

[djmiddelkoop]

Karl, I don't want to spoil your adventure with the Akai AM-U03, but believe me, this bad sounding amp can't be bettered by changing whatever capacitor you can find in there.
As Jacco already mentioned, won't make a change at all.
it fits as a flag on a broomstick (flag op een modderschuit )

 

[Karl vd Berg]

Karl, I don't want to spoil your adventure with the Akai AM-U03, but believe me, this bad sounding amp can't be bettered by changing whatever capacitor you can find in there.
As Jacco already mentioned, won't make a change at all.
it fits as a flag on a broomstick (flag op een modderschuit )

Thanks, man! 🙂

The amp seemed to have a decent sound before these components went kapot.

But anyway, I'll just stick something from my stock in place of these vervelend styrenes and sell it away...

Cheers!