Transistor sub help needed

[Geek]

Hi Wayne,

That's more like it - had to clean it up a little bit in Photoshop, and sharpen it up, but now I see where you are.

Did you click on the pic twice? Shouldn't have needed a Photoshop

Good pick - the NTE 127. I had forgotten that was most of the application for a PNP Ge power - in the horizontal output.

Looks like that one is out, out, out! They want $70 for the thing!!!

Probably obvious to you, but have you tried disconnecting power to the entire bad side, and measuring test points on the good side - if there is a good side? Also, when I had a bad amp in for repair, I usually plugged it into a Variac and came up slowly - without a load, and see if the power supply comes up proportionately.

Yes, I'm properly trained

That's my I didn't see the others actually, because the CM13 tested good at the time

Changing that 680 ohm to 750 was only a suggestion if you had to replace the Ge TO-3 with something in silicon - it would have to compensate the biasing for the additional 0.3v Vbe drop to 0.6v. But since you found a Ge replacement, you wouldn't have change it.

Well, got to now. I've paid less for RF MOSFETS

This one is a tough one - never had one that wiped out so many. Usually an ouput and a driver before it, at worst. Doing a great job - will try to continue with the help. We'll get it to work.

I *always* seemed to get those in the shop... I had thought my co-workers hated me and left me with them

Cheers!

 

[Geek]

Great news! She's working again!

Replaced CR6, Q13, Q15, Q17 and R46.

Here's a twist... remember I said the 1N60, CR8 and CR9 weren't on the board, but jumpered? Well, R46 and R15 weren't 680 ohms like the schematic says, they were 470 ohms! So rather than upping R46 (R15 I left alone in the good channel) to 750 ohms, I upped it to 680 ohms and that worked very wellll so well than when I replaced Q17 with a silicon 2SB554, the bias was perfect without touching R40!!!!

For future reference, CM12's can be replaced by 2SC3332 or 2SC1573. CM9 can be replaced with NTE175 or the generic 2N4233 as you suggested. CM10 with 2N3773, perfect. CM11 can use 2SB554 if the preceeding bias resistor is upped a value.

Again, thank you for all your help Wayne, you've taken a LOT of pain out of this

Cheers!

 

[wayne chou]

Congratulations!

I'm glad it's working. Would have been a shame if we couldn't get it running again. Glad to be of help. And thanks for trying out the subs - will be good to know for the next guy. Good luck.

Wayne

 

[usmdemc2]

CM Labs

Hi Wayne,
First off I'd like to say that I wish CM Labs were still around.

I read from stereophile forum that you have the 35D and the 911 hooked via biamping.

Just wondering if you still have the 35D and 911?

I have the 911 amp, but unfortunately it's in need of repair and I have no idea who to send it to. Do you do repairs?

Thanks Wayne,


Frank W.

 

[wayne chou]

Frank,

Yes, I still do have the 35D and the 911, but I have moved to NC, and have not listened to my system for some time, since it still is up in CT. But the 911 has acted up in the last year or so, mostly because the smaller electrolytics have dried up, now 40 years or so later. So my amps also need to be serviced.

But to answer your question - I have repaired other 35D's which were basket cases for friends. But, I really don't have the time or inclination to do the same again.

After all the time I have been away from the audio scene, I have decided I have a point to make. So I have a new design that I have been working on - totally class A, low distortion mono block without overall feedback, in 50 watt and 200 watt targeted versions, that one can make sound like a tube or transistor amp. I think I have the major bases covered. Let me know what other features you can think of.

I will look at your 911, providing it hasn't been modified and hacked over. But you should realize that my prime focus is on my current new design, which I am anxious to complete and bring to market. So you should not expect immediate attention.

As a previous customer, I am flattered that you have enjoyed your stay with your 911. As such, I want to extend your enjoyment as long as you can with the equipment of C/M Labs. For that reason, my rates are extremely reasonable (more for love than for money) plus parts and shipping. If you are comfortable with this arrangement or wish to ask more questions, contact me at wchou@sbcglobal.net.

Best regards,

Wayne Chou

 

[bear]

If anyone needs it, I also have done repairs on all manner of CM Labs gear...

_-_-bear