how can i drive a complimentary symmetry output stage

[SVI2004A]

ok heres the go...

i have an output IC of which i have the internal schematic (see pic)

and i would like to know how to drive this...
inputs are pin 1+5 theese sit at +/- 1.8V respectively

i have seen one application which had pin 5 connected to -V at via (2x 3.9K resistors in series) which was in series w/ a 68ohm 1/4W fusible

i have taken voltages from application in a set

pin 1 +1.8V (in)
pin 2 +50V (+vce)
pin 3 0V (spkr out)
pin 4 -50V (-vce)
pin 5 -1.8V (in)
pin 6 connected to pin 3 via 560 ohm resistor (protection ref)
pin 7 Level shift (trigger for prot circuit)
pin 8 GND

i am unfamiliar with drive circuitry but know the output stage is a fairly common config (- have seen same layout in discreete amps)

any help would be good as i have some of theese ICs spare and would love to make amps with them

- Baily

[fab]

This is very hard to provide a "perfect" drive circuit for your output IC because the characteristics of the transistors inside that IC are not known. Having said that, you can start with this circuit (Leach amp since a lot of peoples on this forum seem to like it) as example. I have indicated in red the part of the circuit that is covered by your IC and I have marked with numbers where to connect to your IC. Again, some values (compensation RC network may need adjustment). You will need a square wave 10 kHz generator and an oscilloscope for that.

[SVI2004A]

ok i am going to try the leach amp front end on one of my power ICs

can anyone tell me if this Voltage amp seems like a good idea
www.electronics-lab.com/downloads/datasheets/stk/STK350-020.pdf

it looks to be an easy compatible option (i hope)

i believe this will work - anyone here think it won't ? - why?

plz gimme ideas ppl

- Baily

[SVI2004A]

fab > This is very hard to provide a "perfect" drive circuit for your output IC because the characteristics of the transistors inside that IC are not known.

well, this isnt *exactly true*

quite a few are SMD

the PRE Drive Q3 & Q4 are Raw block
the Output stage Q5 & Q6 are Raw block
the Bias Diode QD1, the (i guess transistor shorted to make diode)
Bias Transistor Q7
Stabistor pack DP1
Overload det Transistor Q8
Overload Diode pack (2 diodes in 1 3 pin pack) DP2 ARE KNOWN VALUES... just i dont know the values of SMD devices

However, i shall list (and hope to the higher being that someone can solve the codes?)

a few different device codes that were used over the production will be listed

Q1 - DG and/or DL
Q2 - CG
Q3 & 4 RAW BLOCK (pre drive)
Q5 & 6 RAW BLOCK (Output)
Q7 - AN
Q8 - CG, I·S, 2F·S
DP1 - M.C
DP2 - M.O
QD1 M.F

anyone know where to decypher SMD codes? this would help heaps!

i look forward to hearing from you

- Baily

[Quattor]

I have seen Grundig FineArts A9000 integrated amplifier using STK3102IV as the driver, while the output was descrete - like in your IC - triple darlington. As far as I know STK3102IV is obsolete and it's direct successor is STK350-XXX. Since you're OK with IC output then you'll sure be OK with this thing driving it. Oh, by the way, that Grundig amp - it was quite nice piece of equipment so don't worry :-)...

Regards,
Nick

[sam9]

Does the IC have a name? if so does it have a data sheet that offers suggestions?

[SVI2004A]

The IC on the Schematic is a SVI2004A
but also the STK2058IV is the same
also STK2028 2038 2048 (either flat or IV series)
the MK2 type of the STK has 22 pins and is completely diff in lay out

god knows *how long ive been trying to get a datasheet for any of the abovementioned ICs*

the SVI i have reverse engineered

[fab]

The STK-350-020 will surely work to drive your IC. However, you "may" have to tweak the RC compensation network (between pins 3,4 and 6 and also the 150 pf at collector-base of the discrete transistors) because the application in the data sheet is based on the specific selected discrete transistors. Maybe I was misleading, but it is more efficient to adjust the few components values than trying to determine the whole effect of combining the STK-350 with your IC. In fact, it may just work as-is without any tweaking, just try and see. In addition, the gain is 101 in the application (which is a little bit higher than most power amp on the market).

[sam9]

"god knows *how long ive been trying to get a datasheet for any of the abovementioned ICs*"

I googled anf see your point.There was one place that offered to SELL you a datasheet for 30 Euros!!

[SVI2004A]

id like to see the link to that

id buy it if infact is the proper datasheet!

hard to track due to SVI being a Technics custom IC

but STK 20*8IV series would be just as good
else STK 20*8 series