Ready to shoot my Series 2 Model 200

[laatsch55]

Also Chas, I held up on sending the 2SD555's for this. You'd be better off going with the MJ 21196's for this project.

 

[ChopperCharles]

I don't want to spend money on a whole new set of outputs for this thing until I verify it actually works. If it works, then I'll think about upgrading the sound.

Charles.

 

[laatsch55]

Dids you answer Joe's post?

 

[ChopperCharles]

I did not replace Z1. I'm waiting on one now, hoping that will fix it.

I don't see a question asked by anyone named Joe.

Q1 MPS-a93
Q2 2N3415
Q3 2N3440
Q4 MJE15050G
Q7 BC337
Q8 BC 327
Q9 MJE15031G

 

[laatsch55]

My bad......Joe=Gepetto, Gepetto=Joe....

 

[Gepetto]

I did not replace Z1. I'm waiting on one now, hoping that will fix it.

I don't see a question asked by anyone named Joe.

Q1 MPS-a93
Q2 2N3415
Q3 2N3440
Q4 MJE15050G
Q7 BC337
Q8 BC 327
Q9 MJE15031G

Do you mean MJE15030 for Q4?

You should be using MJE15034/MJE15035 or MJE15032/MJE15033 for Q4 and Q9 respectively. You are living on the edge with MJE15030/MJE15031 in these two locations in the PL200.

What are you using in the Q5/6 and Q10/11 positions?

You can bring up the amp and check everything out with all 4 main output devices removed. You cannot drive speakers with the outputs removed but you can check out everything else in a safe mode manner.

 

[ChopperCharles]

Yes, that should be 30, not 50. Those were the parts supplied in the qua-co rebuild kit, which was put together specifically for this amp.

q5/6 and q10/11 are the original 2sd555 and 2sb600 drivers. I have one complete good set , so I can test one channel at a time.

Charles.

 

[Gepetto]

Yes, that should be 30, not 50. Those were the parts supplied in the qua-co rebuild kit, which was put together specifically for this amp.

q5/6 and q10/11 are the original 2sd555 and 2sb600 drivers. I have one complete good set , so I can test one channel at a time.

Charles.

that is bad advice they gave you

 

[Gepetto]

Yes, that should be 30, not 50. Those were the parts supplied in the qua-co rebuild kit, which was put together specifically for this amp.

q5/6 and q10/11 are the original 2sd555 and 2sb600 drivers. I have one complete good set , so I can test one channel at a time.

Charles.

Hi Charles

As Lee has advised, the MJ21195/MJ21196 transistors are far superior to the original 555/600 complements in every aspect.

 

[ChopperCharles]

Hi Charles

As Lee has advised, the MJ21195/MJ21196 transistors are far superior to the original 555/600 complements in every aspect.

I don't care, I don't want to spend a lot of money on this hunk of junk until it is working. And even then, I already have a 200 amplifier, this will be a backup.

Charles.

 

[Northwinds]

I don't care, I don't want to spend a lot of money on this hunk of junk until it is working. And even then, I already have a 200 amplifier, this will be a backup.

Charles.

If you do what Joe advised, you won't even need the other amp as the amp your working on will outperform your good one. How long until your working one goes bad? Your comment confuses me, you want to get the amp working before making it better??? So your going to buy parts twice and tear it apart twice?

 

[laatsch55]

Well Charles. Seems to me Joe said the amp could be tested without installing the outputs. So you don't need to put those at risk. But if , as you say, you don't care then don't expect us to....for we all have other things we can be devoting our time to.
The 2SD555/2SB600 combos have been out of production for over 20 years. I do have a pretty good stock of them. I also feel as the primary output pairs for a number of classic amps that using them as sacrificial lambs is not in their best interest either. I was keeping them around for folks who wanted their stuff fixed with factory originals. Some say they can hear the difference. Who knows, but if a guy wants the NEC devices in his Spec 2 instead of the On-Semi devices then it's nice to have a few . If your motivation for wanting the NEC'S was my offer to send them for free then I'll send some 21196's instead.
It does make me wonder about your commitment to fixing this amp if 12.00 worth of outputs is a make or break decision for you....
We have a history, here at Phoenix, for bending over backwards for folks who need help. However, ones attitude has everything to do with that help being continued. You are not entitled to help just being here, nor our undivided attention by posting. A somewhat convivial approach goes a long way around here ...We do not require slavish ass kissing....but a thank you once in a while is appreciated...

 

[wattsabundant]

If both modules were sent to me, I'll have some time I could fix them. JUst heatsink board and parts Idont need the power supply or parts

 

[ChopperCharles]

Well, I want to thank everyone that helped. I finally got the left channel working. The problem was Q8. It was causing excessive current to be drawn, which blew out Q2.

That channel is working now, and now that I have one working channel, I should be able to get the other working, since I have something to compare it to.

As for the 2SD555's... I'm not sure how you equate replacing them as costing only $12. The way I understand it, I can't just replace the two 2SD555s, I also have to replace the 2SB600s. And I can't just replace them in one channel, I have to replace them in both. Which is going to be more than $12. What's more, the market is glutted with counterfeit semiconductors. So I was hoping to get two known good replacements from a reputable source, and not have to worry about buying 8 new transistors and maybe getting stiffed with fake chinese parts. What's more, I also understand there are serious oscillation issues with some of these replacement semiconductors, and I want to avoid that completely, because I don't have any way to test for or correct oscillations.

Anyhow, I just put a bid on some 2SD555s on eBay. Hopefully I'll be able to snag them for a reasonable price, take the two I need, and then resell the rest.

Again, thanks for all the help so far. I've got some parts to order now, but I'll post back when I get the right channel working as well.

Charles.

 

[laatsch55]

Charles, the 200 won't oscillate with the 95's/96's....PM your address again and I'll send ya some..

 

[laatsch55]

Also on the 555/600's there are 3 3 different gain levels. These are reflected in the Q,R, and S suffix on the part numbers. If you can, be sure and get the same suffix for both the 555's/600's....

 

[ChopperCharles]

So if I have one good, perfectly working channel, and one bad channel, what differences should I be looking for to narrow down the bad component(s) on the other board? Right channel is giving similar issues, negative rail on output, with our without power transistors installed. However, the difference here is a dim bulb tester lights briefly and then goes dark. Before I finally fixed the left channel, the left channel caused the tester to to burn brightly.

Charles.

 

[laatsch55]

Have you tested the Bias tranny on that channel too?

 

[Gepetto]

So if I have one good, perfectly working channel, and one bad channel, what differences should I be looking for to narrow down the bad component(s) on the other board? Right channel is giving similar issues, negative rail on output, with our without power transistors installed. However, the difference here is a dim bulb tester lights briefly and then goes dark. Before I finally fixed the left channel, the left channel caused the tester to to burn brightly.

Charles.

Likely means you have a shorted Q5 or Q7 on the control board if it does it without the output stages installed. Or a shorted flyback diode on the backwall.

 

[ChopperCharles]

I'm getting different resistance values on several diodes and transistors, but nothing that shows shorted. I replaced Q1 just to be sure. Will look into it more deeply soon.

It'd be nice if there was a real test procedure... remove everything, and go through step by step checking voltages and or resistances. Fix one stage, move on to the next, make sure that one works, and continue, until the problem is found.

A man can dream... Sigh.

Charles.