audio-talk

Tbh I haven't the space for anything physically bigger, thats why the big Sony I had isn't in there. The MF X ray I had would have fit, and the inca design katana would have been marginal. It does do something nice though, its musical

If I could get hold of another x ray I would, and I'd like one of those sony cdp x3000es players. Those were the top loaders with the perspex disc cover and were about 12" square. A Cyrus would fit, but there aren't many others that would fit without a big rethink on where everything is.......
The shonky old Philips will do very nicely though, I even quite like its 80's tastic looks

Ordered a pair of the op amps nick recommended which should arrive shortly.
Any reason I should bother with a pair of sockets? The originals are not in sockets, just soldered straight to the board.
Im not planning on playing with different op amps.

Oh and I bought another player, a cd371. Midi sized again, it doesn't have the flap in front of the transport drawer, just a solid drawer.
It was only 25 quid so i took a punt on it. Plan is to modify the heck out of that one once ive put the standard mods to the test in the 160, to take it further with stuff like the caps on the tda1541, maybe a separate reg for the saa whateveritiscantremembernow chip, maybe a new clock.

Also, is a solder wick a better bet for desoldering parts from a pcb than a solder sucker? It was a bit of a pig to get some of the caps out, p'raps some of our repair tech trained guys can elaborate on beat practice for this kind of thing. Cant imagine it'd be all that easy to desolder one of the large IC's with a sucker tbh

I try always to use sockets in case I bu55er up a chip by overheating it with soldering iron.

Good point mike
I'll get some

The way I normally remove a DIL package is by sacrificing the chip, clip all the leads with snippers, so you can take each out as a single wire. The other way that works well is to use a elastic band around the end of some long nosed pliers to hold then shut, clamp the pliers on the chip with the board upside down and the pliers hanging down. Then use a hot air gun to heat all the pads at once until the chip is pulled out. You can do the same from the front, but can risk other components IMHO.

https://hackaday.com/2016/01/12/desolde ... ike-a-pro/

I wanted to ask this possibly numpty question and please don't flame me for it ------

Those op-amps are very wide bandwidth *apparently.* Might their use not cause oscillation in the circuit because of this? Even traditional audio op-amps go out to MHz I understand.

I wish to gain knowledge - forgive me for asking (Nick). I have another question about types of signal coupling caps but have been too scared to ask as on other forums, I've been made to feel an utter twonk for my ignorance and paucity of knowledge

Ask away Dave, there are probably a few that will learn from the reply.

I feel like an utter twonk most of the time dave
I just dont care though
When i first started looking at this, alot of the info said to use a small ( pf) cap to prevent this, however it appears in alot of cases to be a preventative measure rather than anyone actually confirming it is a problem and curing it.
I know practically nothing about op amps, hence taking nicks recommended op amps as read. He knows about these things. Im sure that if it does break into oscillation I'll know, (probably) and then be able to cure it.

There is always a possibility that changing op amps may cause instability, adding a couple of small caps will probably cure this, but its a good reason to use sockets.

Its also possible you wont notice instability without a scope.

I have found those LME's are generally forgiving.

Nick wrote: ↑Tue Sep 26, 2017 10:40 am There is always a possibility that changing op amps may cause instability, adding a couple of small caps will probably cure this, but its a good reason to use sockets.

Its also possible you wont notice instability without a scope.

I have found those LME's are generally forgiving.

Sockets come with their own risks - inter-pin parasitic capacitance & inductance, whilst small (can't find figures at the moment), can affect the top-end of the audio spectrum especially if coupled with a large value feedback resistor (makes an LPF).

Just something to consider...

jack wrote: ↑Tue Sep 26, 2017 12:39 pm

Nick wrote: ↑Tue Sep 26, 2017 10:40 am There is always a possibility that changing op amps may cause instability, adding a couple of small caps will probably cure this, but its a good reason to use sockets.

Its also possible you wont notice instability without a scope.

I have found those LME's are generally forgiving.

Sockets come with their own risks - inter-pin parasitic capacitance & inductance, whilst small (can't find figures at the moment), can affect the top-end of the audio spectrum especially if coupled with a large value feedback resistor (makes an LPF).

Just something to consider...

Yep, but in that sort of situation, changing the op amp itself will probably cause a larger effect.

When I mentioned risk of cooking the chip with soldering iron, I meant more in terms of soldering the new one in, not taking the old one out.

Ahahaha.... But if i solder a socket in, I wont cook the chip trying to solder that in!

Ant wrote: ↑Mon Sep 25, 2017 10:06 pm Also, is a solder wick a better bet for desoldering parts from a pcb than a solder sucker? It was a bit of a pig to get some of the caps out, p'raps some of our repair tech trained guys can elaborate on beat practice for this kind of thing. Cant imagine it'd be all that easy to desolder one of the large IC's with a sucker tbh

What I've found is...

IMO braid/wick is an alternative to use if the desolder pump isn't removing enough solder and the joint is still manky. I've worked with Technicians that can't stand it, and others that have worked wonders with it, there's a knack to using it correctly.

One of the dangers of using braid is that it can lift the track of the PCB if you've left the iron on it for too long, but if you haven't held it on for long enough... then the solder wont flow into the braid. Its a knack. Maybe practise on an old PCB 1st before tackling the CD player?

Sometimes feeding new fresh solder into a stubborn joint/pin then desoldering again works wonders IME.

If you do buy braid, keep it in an air tight bag, it's way more efficient when its fresh and not oxidised.

Also, if you want to remove a many-legged component that you don't need anymore, sacrifice it, cut its legs off (and thats coming from a veggie!), remove its body then you can just work on removing each pin cleanly by using a thin tip on the iron and using a thin non-heat conductive pointy thing to form a pincer type motion to remove the pin from the PCB from the component side of the PCB .

Thats what works for me.

Dave the bass wrote: ↑Wed Sep 27, 2017 8:49 am

Ant wrote: ↑Mon Sep 25, 2017 10:06 pm Also, is a solder wick a better bet for desoldering parts from a pcb than a solder sucker? It was a bit of a pig to get some of the caps out, p'raps some of our repair tech trained guys can elaborate on beat practice for this kind of thing. Cant imagine it'd be all that easy to desolder one of the large IC's with a sucker tbh

What I've found is...

...all the above, plus...

...the type of wick is very important - a lot of solder wick is just crap.

I only use Chemtronics Soder-Wick - available from loads of places.

It's not cheap but, IMHO, by far the best out there. It wicks comprehensively, reliably and cleanly .

Cleanup/Wipe the desoldered pad with a cotton bud dipped in IPA (IsoPropylAlcohol, not beer).