Repairing a Soundcraft Delta Theatre..

[DanSteely]

After many years of suppressed lust I finally purchased a Delta and am now starting to go though the various faults on this 20 year old desk.

 

I wonder if anyone can recommend Rapid (or other supplier) equivalents for these:

 

Transistor: B737 SRG (According to the circuit diagram the transistor is a 25B737)

 

IC: 072B JRC 4013B (According to the circuit diagram the IC is a TL072)

 

BTW:

 

Many thanks in advance..

[mervaka]

Is the datasheet for those parts, or the schematic for the Delta available? Without either of those, I doubt you'll have much luck in working out what you need.

[timsabre]

TL072 is still commonly available

eg http://uk.farnell.com/1103005

 

according to google NTE290A is equivalent to a B737

http://uk.farnell.com/4524767

 

[DanSteely]

Just the job.. Many thanks

[Brian]

...the transistor is a 25B737)

That ought to read '2SB737'

[alistermorton]

TL072 is still commonly available

eg http://uk.farnell.com/1103005

 

according to google NTE290A is equivalent to a B737

http://uk.farnell.com/4524767

 

 

Quite a bit of discussion at here"]http://www.groupdiy....ic=38523.0 too, coincidentally regarding fixing a delta.

[laolu]

Dan,

You seem to have a circuit diagram - right? - and know what you're looking for.

If you have trouble finding the 2SB737 and/or TL072, let me know. Maybe I can get them for you in a local shop, that sells all kinds of exotic semiconductors.

 

Norbert

[boatman]

There is a low noise PNP transistor which is the exact equivalent of the 2SB737; the 2SV888 (datasheet here) made by Cool Audio especially for Audiophiles. Unfortunately, it only seems to be available ex-works in China but they appear to offer small quantities (at only $0.20 each!) by mail-order on their website here.

 

As the 2SB737 was originally designed for moving coil RIAA preamps, it expects a source impedance of less than 10 ohms. For a 600 ohm mic input you could use either BC557 or 2N4403 and still have a minimal noise floor. Be aware that the pinout of both BC557 & 2N4403 are different from 2SB737 & 2SV888 so will need to be rotated in the PCB.

 

Do not be tempted to replace the TL072 with the widely available TL082 as the latter's noise figure is much higher.

 

Edit to add: Just noticed that Cool Audio won't process orders less than $2000! Bu$$er.

[DanSteely]

The Farnell handling charge is very expensive... Can anyone suggest a different (cheaper) supplier? (I've tried searching for the Farnell recommendations at Rapid but have come up with nothing...

[gyro_gearloose]

The Farnell handling charge is very expensive

I was about to ask if Farnell still offered free next day delivery, like they did the last time I ordered from them many moons ago. Then I remembered that their website lists stock held in other countries and that they charge to get it shipped over to the UK. To be honest, if Farnell don't have what you need in this country the chances are that no one else will either, and getting things shipped over will cost you no matter where you buy them from.

[Bazz339]

Could you get them from RS Components ? They have depots all over the country, you may need to register or have an account but can buy over the counter.

 

CPC is part of the Farnell group, they had a charge of £5 or so for orders under £45 (I haven't checked recently) I don't know whether Farnell are the same. I don't think that is unreasonable, maybe you could buy through CPC if needed even if it is not listed? Might be worth talking to them. CPC stock 1000s of other items more consumer orientated so if I don't need it in a hurry I usually add it to a basket on line and wait until I am past the minimum order.

[boatman]

Currently carriage is free on ALL online orders with CPC regardless of value. I don't know how long this will continue.

[timsabre]

Farnell do free delivery on any value order if you have a credit/trade account with them and order on the website, but charge handling/carriage for credit card orders.

You can't buy Farnell stock through CPC although they do stock some of the same things (CPC's semiconductor range is small).

[DanSteely]

Hi Boatman,

 

The BC557 transistor is available from CPC & Rapid. Unit price is low and similar from both but CPC will charge £5.95 handling charge + FOC delivery, Rapid will charge £3.95 delivery + NO handling charge.. Rapid wins..

 

Their slight variation is here: http://www.rapidonline.com/Electronic-Components/Bc557b-Transistor-Pnp-To-92-50v-81-0474

 

Will this once do?

 

Many thanks.

 

 

 

 

[boatman]

Yes that one will do, but as I said earlier, delivery on all online orders placed with CPC is free at the moment and they have the BC557 at only 5p + VAT! Link. They also have TL072 in DIP or SOIC.