GK 250ml amp transistor replacements

[nosaj]

I've got a GK 250ml amp ecg390 and ecg 391 are shorted

ecg390 I find NTE2316 or 2sc3927 but HFE is a lot higher
ecg391 not finding a replacement substitute.

What effects would a higher hfe regarding sound?

to218 package Si NPN 80w 10a ecg390
Si PNP 80w 10a ecg391

Thanks for any insight,
nosaj

[nosaj]

Ok Looks like originals are tip33c and tip34c So I'll look for those.

nosajgallien_kruger_250ml_250rl_212scl.pdf

schematic

[nosaj]

Ok Looks like originals are tip33c and tip34c So I'll look for those.

nosaj[ATTACH]46949[/ATTACH]

schematic

Ok I can find tip33cg on mouser but not a tip34c
nosaj

[nosaj]

Ok I can find tip33cg on mouser but not a tip34c
nosaj

i think I can use tip42 in place of tip 34

[52 Bill]

i think I can use tip42 in place of tip 34

Those come in TO-220 sizes so that won't work for the outputs.

[nosaj]

Those come in TO-220 sizes so that won't work for the outputs.

Got any suggestions?
tip36c? so237 package
Thanks,
\nosaj

[52 Bill]

Yes, TIP35C and TIP36C will work as comp. pairs.

TO-247-3 package

[nosaj]

Yes, TIP35C and TIP36C will work as comp. pairs.

TO-247-3 package

Well I only ordered one of each and smoked q27 because a tip30 was also shorted. Not wanting to make another order is this possible to do?
I have some 2sc3281 and 2sa1302 on hand.could I use these in place of q27 an q31 which ask for tip33 and tip34c

i see that they are planar which I believe is just a manufacturing process. If they will that would be great.

Thanks,
nosaj

[Enzo]

just a manufacturing process

Well, that is the thing. You don't want to mix output types. All of one or all of the other. The transistors have to act together, we need them to track. Different processes and such mean we can't tell if they will track thermally or if they will share current well.

[nosaj]

Well, that is the thing. You don't want to mix output types. All of one or all of the other. The transistors have to act together, we need them to track. Different processes and such mean we can't tell if they will track thermally or if they will share current well.

I have enough to replace q27, q13, and q17 and q31. That would cover the outputs I believe.
nosaj

[nosaj]

I have enough to replace q27, q13, and q17 and q31. That would cover the outputs I believe.
nosaj

Ok I didn't quite follow your advice. Here's what I did. Because it's a stereo amp and one channel was shorted. I replaced the shorted transistors with 2sc3281 and 2sa1302 for q27 an q31 . Which works but that channel has lower output, which leads me to ask are transistors similar to tubes in the effect that different ones can require more signal to drive them? Or am I thinking incorrectly on this?
Either way I'm thinking of getting the correct ones anyways.
Reading the service manual procedures one of the steps says to tap Brain on bench a few times to make sure nothing fails.. I'm sure they mean the circuit board but that not what they said.

Thanks,
\nosaj

[nosaj]

Ok moving on. I am out in the Sticks right now with just a multi meter. The chorus and echo do not seem to engage(work).
Looking at the schem Chorus has u17 right after the switch It looks liks tl604 is just and electronic switch. So by pressing the switch on the front pin 6 or 7 should open or close I believe. Same for the one on the echo.
Is this correct in thinking?
I went through the schematic and located test points and the only things that stood out was D9 show -13.58 and 15v TP's would show 14.70 ish
45vrail 46 and -45v -47.96 Which I thinkk would suggest replacing that cap.

Thanks,
\nosaj

[nosaj]

Ok moving on. I am out in the Sticks right now with just a multi meter. The chorus and echo do not seem to engage(work).
Looking at the schem Chorus has u17 right after the switch It looks liks tl604 is just and electronic switch. So by pressing the switch on the front pin 6 or 7 should open or close I believe. Same for the one on the echo.
Is this correct in thinking?
I went through the schematic and located test points and the only things that stood out was D9 show -13.58 and 15v TP's would show 14.70 ish
45vrail 46 and -45v -47.96 Which I thinkk would suggest replacing that cap.

Thanks,
\nosaj

I recapped the amp and replaced the q27 and q31 It comes up on the lightbulb limiter ok, bulb is real dim. When put on mains it is ok for a second then takes off and q31 shorts out.

I'm using tip35 and tip36 somewhere recently I remember Juan saying this pair might not be the best for driving speakers as they'd burn out quickly in this application. But for the Life of me I can't find it here. I'll have to check SSguitar for it.

Anyone have any tried and true output transistors for in place of tip 33 and tip 34's?

Thanks,
nosaj
Here it is.. Would this apply to my situation ?


Personally I have always been disappointed by TIP35/36 ; look great on paper (100V 25A 125W dissipation) but are sissies out in the field.
After minutely rereading their datasheets many times, I noticed (hidden in plain sight ) that their SOAR rating is appalling ... and THAT is what kills bipolar transistors when driving complex loads such as ..... um ...... speakers.
I would use TWO pairs in the 150W amp, not one as optimistically stated in schematic, I guess around 45V rails.

[52 Bill]

I would use TWO pairs in the 150W amp, not one as optimistically stated in schematic, I guess around 45V rails.

As far as I know the two power amps in these things are rated at 50 watts each.

I have used TIP35C and TIP36C as replacements for the outputs on these with no problems.

[Jazz P Bass]

Notice the key letter?

"C"