Mod your Beresford 7520

[StanleyB]

Hmm, when I asked a few days ago if all of the replacement opamps would benefit from the cap, Stan said yes. Could you please clear this up Stan?

I suggest that you refrain from doing any sort of repairs or mods if you are not familiar with the requirements regarding opamp power supply decoupling.
For reference, see the manufacturer's datasheet of the component you intend to use, and also read up about it ' The Art Of Electronics' by Horowitz and Hill.


Stan

[Covenant]

Pssst Leo-can you help here?

[apmusson]

He has done the whole thing for me. Ordered the THS4032CD opamps, supplied the caps and SOIC to DIL boards and soldered it together. Total cost inc p&p = £19.70.

Will let you know how it works out when I get it.

Ade

The guy who is soldering my THS4032CD to the 'SOIC to DIL' boards wants to know whether I need round or square pins (see email below)

"We can supply them with round or square pins.
Round is smaller & allows them to be plugged into a turned pin IC socket but
on some plugboards the round pins sre too small to be reliable on the
plugboard & need to be plugged into a turned pin IC socket which in turn is
plugged into the breadboard. Square pins are ideal for plugging into a
breadboard but are too big for a turned pin IC socket. They can be forced
into a leaf spring IC socket but it's not an elegant solution.

Which do you want. Square(0.9mm diagonal) or round (0.5mm diameter)?"

Can anyone advise which I need? I assume its the round pins?

Thanks

Ade

[sponge]

Which do you want. Square(0.9mm diagonal) or round (0.5mm diameter)?"

Can anyone advise which I need? I assume its the round pins?

Thanks

Ade

OK, the pins on the BrownDog adapter I have used are 0.5mm round. Hope this is what you need.

Ken

[apmusson]

OK, the pins on the BrownDog adapter I have used are 0.5mm round. Hope this is what you need.

Ken

Thanks Ken. Thats just what I needed to know.

[leo]

Pssst Leo-can you help here?

I'm afraid I can't offer any solid answers because I don't own the TC-7510 or 20 so don't know how any of these replacement op-amps react in this particular unit, all I can do is offer advice on things maybe worth trying
For all op-amps I try in any of my own gear I check for instability/oscillations,temp issues or any nasties, read the spec sheet to make sure its at least got half a chance to work in the particular application

Some of the faster higher bandwidth types like video rated op-amps usually require much more care and tend to be less suited as a drop in replacement, sometimes they will work fine yet sometimes require additional work, it may sound ok for a while but that does not guarantee its not suffering from some HF oscillation
Some op-amps are also not suited to be used at unity gain

LM4562 is a device rated for Hi-Fi audio and its unity gain stable, of course care should still be applied but you have more chance of getting stable results with this one than some of the other higher spec types

Without droning on too much more
I think the metal can LM4562 should be ok ,the onboard bypass ceramic should be adequate and should not need an additional one, looking at the pic apart from the socket the cap looks close to the pins(unless theres some weird long track) , ideally (If it was me) if the thing measures ok and I was sure this op-amp is the one I want to keep not wanting to try others I'd go as far as removing the DIL socket and soldering the op-amp direct to the pcb.

[Covenant]

Thanks Leo,
Assuming an op-amp did cause HF oscillation would removal and replacement with a more basic one solve the problem or is it possible to do permanent damage?

[HighFidelityGuy]

Thanks guys, I'll leave the caps off for now and see what happens.
I've formed and trimmed the legs of my 49720's to make them as short as possible and I'll fit them tonight. I'm going to borrow an antistatic wrist strap and mat from work just to be on the safe side.

The wife's working late tonight so I get lot's of uninterrupted listening time. Perfect timing.

[leo]

Thanks Leo,
Assuming an op-amp did cause HF oscillation would removal and replacement with a more basic one solve the problem or is it possible to do permanent damage?

Depends, mainly the damage would be to the op-amp internally, if an op-amp starts to suffer from bad oscillation it will over heat, continued use whilst over heating can make the op-amp go noisy, sound distorted or hissy.


Problems to the circuit outside of the op-amp can be things like burnt resistors, damaged regulators etc, if the op-amp oscillates it can put much more strain on the supply, causes the whole thing to ring like buggery
Some cases the thing feeding the op-amp or being fed from the op-amp may get damaged, things should be better protected though if input and output coupling caps are used

[trailer]

I've been running 4562's and 49720's for a week each, with no cap, constantly with no issues.