i need help with teleton ga 202

T

toppergraph

Chris
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Hello all,
i`m new to this i need some help with a teleton ga 202 the output stage is shot and i am having trouble trying to get replacement power transistors c1060(all four) if i remember a darlington arrangment.i`m sure a modern general purpouse off the shelf power transistor would do case To220.

i was a fully trained tv then later audio/video engineer but left the trade in the mid 80`s for computers so rusty on the old discrete stuff.
this little project as has re kindle good memorys of building are own disco equipment light shows and all using bi-pak amps and visits to totenham court rd in the late 70`/early 80`s.

any advice/help appreciated.

best regards
 
Didn't think I had this but just found it:


TeletonGA-202lowres.jpg
 
GREAT Thank you robert,

if i remember would it be wise to change all four transistors in each o/p stage as its directly coupled?

i am sure TIP 41c will do the job for asc1061 the others look very familier
anyway going off to find parts and will keep you posted .Whats the best way to let you know how i get on.

once again thank everyone for your efforts.
 
T DAAh,
managed to obtain the origianl 2sc1601`s @ 50p each from my old boss at
ROXI Audio coventry.He has had them for years.when i showed him the circuit that Rob kindley supplied his eyes lit up and said "i remember them a very good amp for the time, don`t forget to replace the whole driver stage as well its DC coupled remember" YES my old knowledge is returning.The rest of transistors are off the shelf from Maplin for pennies.
one thing that was puzzleing me; why both channels were blown.So i asked the question to my mate whoose unit it was; reply "Well i connected both speakers to the one that worked".
Ive booked a day to attempt the repair next week at his flat(i don`t have old din connecters and want to ensure his speakers arn`t Fried first).

It will either be HOO-RhAA or never mind its your round and get the missus one too.

I will be back and let you Know the outcome

having fun with electronics again thanks all topper.
 
pete693 said:
Please check this out before installing but I think you can substitute a TIP 41C for the 1060.
Pete.
Click to expand...

Thanks i`m sure you are right the data sheets say yes but i could not buy local
since then i had abit of LUCK(THIS thread is turning into a book).

THANKS again topper.
 
The amp has a capacitor coupled output so while you have it dismantled it might be wise to replace the output caps. These have improved massively in 30+ years. 64v 2200uf or even 3300uf should now fit the board.
C8 on the above schematic.
 
output caps

yes already thought of this, i can get them from maplin although there axial types i can still do a neat job. as you say i have to remove them anyway to get at the o/p transisters.i shall complete the repair this week so keep fingers crossed.
will keep you posted.

thanks again for advice Topper.
 
bad news guys,
changed all drivers and o/p tr`s o/p, coupling caps applied h/sink compound to all tr`s removed flux from pcb(still have some real solder).

switched on: increased volume:distorted both channels:left hand channel very low(suspect origianl faulty channel):just about to cheack bias voltage then FIZZZZZ smoke left hand pnp(q4) fried.

i`m not going to investigate any further. although i enjoyed the challange i do not have the test gear or workspace anymore and it was very dificult to get the correct bits.

ho hum i tried and there`s only 2 off 2sc 1061`s left on the shelf.(in cov).

thanks again rob and pete for your efforts.

reluctantly giving up(only on this one) Topper
 

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