:lmao:   :dbtu:

BTW...I happened to touch base with a fellow at Yorkville Sound (the company that makes Traynor amps) and he told me their current replacement for the 2SC2233 is a MJE15032.

So...even the amp maker themselves don't replace the output transistors with original parts!

Thanks Enzo.  I really appreciate all the help that you and the others have given me on this.  I am going to spend a little more time really testing the amp today and then I'll find out if the owner has his heart set on 2SC2233 replacements or is happy to stick with this pair of TIP41C transistors instead.

Once all is good, I guess I can turn my attention to another Traynor with issues...a BLOC100K that I *THINK/HOPE* just needs the pots cleaned...

Well...I was waiting to see if I could source some replacement 2SC2233 transistors before going any further but I still have some digging to do there so I figured I would try a pair of TIP41C that Enzo recommended in the meantime.

I'm happy to report that the amp now plays much cleaner and much louder through the speaker...even after several minutes!

There were a few buzzes and rattles so I can't confirm that everything is "perfect" yet but I'm 99.9% sure that's because the chassis is still separate from the cab and everything (including a bunch of the hardware) was sitting on a pretty shaky table top!

I guess my big questions now are:

• should I be looking for other parts of the circuit that may have caused the transistor(s) to fail or can that just happen on their own?
  
• are the spec. differences between the TIP41C and 2SC2233 transistors cause for any concern in the functionality (and stability) of this circuit?
  
• will the spec. differences between the two transistors have any SIGNIFICANT impact on the SOUND of the amp (to be honest, I've never heard this amp as it's SUPPOSED to sound so I can't say if the current tone is better/worse/the same as it originally was)?
  

In other words, can I assume the problem was JUST a faulty output transistor (or two) and consider it "fixed" with the TIP41C swap or should I dig deeper for problems while also continuing to ultimately source the original 2SC2233 replacements?

Thanks Enzo.

Sounds like my best bet is still pulling the 2SC2233s...to either test or simply replace.  I do have access to an oscilloscope so I'm curious to know if anyone thinks I should check anything with that BEFORE desoldering the transistors?

My apologies...I SWEAR the datasheet I had showed the collector on Pin1 but it looks like the 2SC2233 goes: 1-Base, 2-Collector, 3-Emitter.

   

Given that, my measured voltages are:

Q7
B=0.528
C=28.88
E=0.011

Q8
B=-28.3
C=0.011
E=-29.06

Reasonable?  Helpful?

- brad -

My apologies...I still haven't pulled the output transistors from the circuit so that I could test them properly; however, after watching a solid state amp repair by D-Labs on YouTube, I decided to do a quick collector voltage measurement on the two 2SC2233 trannies just like he did.  The one with the more stable resistance measurements (Q7) measures 0.528V while the one with the wandering resistance measurements (Q8) measures -28.3V...I assume they should be a little closer to the same value

I tried measuring resistance across the Base/Collector/Emitter of the two 2SC2233 output transistors without removing them from the board and Q7 behaved fairly well but the meter never really seemed to settle on Q8 and, aside from the 150 ohms across the base and emitter (pin 1 & pin 3), the values were something like 300 mega-ohm.

I guess I should really pull them from the circuit and test them properly...but, as Enzo pointed out, it seems hard to believe they were damaged, then roared to life after I re-flowed all the solder pads, and then spontaneously died again...but maybe that points to the issue...

The speaker tested OK a few days ago but your response made me think I should test it again.  I connected another amp to the TBM-25's speaker and it sounded fine.

I also connected the TBM-25 to two separate speaker cabs and it sounded just as bad as it does connected to its own speaker.

Finally, I soldered new speaker wire to the TBM-25's circuit board and ran that to the speaker and it still sounded bad.

Looks like the problem still lies within the amp somewhere...

- brad -

Interesting...so the headphone output sounds clear because there's enough current for that particular load?

I did some quick measurements:

R125 should measure 10 ohms and it does...with no signs of burns or broken traces

R122 and R123 are the 0.5 ohm 5 watt resistors and they measure 0.5 ohm

R120 should measure 22 ohms and it measures 21.9 ohms

R119 and R121 should measure 150 ohms and they measure 148.6 (R119) and 150 (R121)

Quote from: Enzo on August 20, 2020, 02:09:00 PM
You soldered some stuff and it came to life then failed again.  Sounds like you have a bad connection or cracked copper trace somewhere.  Not so much a bad part.  Transistors don't generally die and heal themselves.

I suppose that's very true!  The fact that I fixed the output...even if just for a moment...certainly gives me hope that I'm making progress.  The downside is that a bad connection or cracked trace might take a while to find...especially since the solder pads seem so fragile on this board!

Quote from: Enzo on August 20, 2020, 02:09:00 PM
Perfectly normal for the two 330 ohm resistors to get hot.  Hopefully there is about 7.5v across each of the two diodes.

I measure a 20.2VDC drop across the positive 330 watt resistor and 20.1VDC across the negative.  Then I have -8.2VDC on one side of one diode and +8.00 on the other diode (-0.00 on the other side of both).

Quote from: Enzo on August 20, 2020, 02:09:00 PM
With speaker connected, how does the line out sound?  Run that to some other amp.  Does the line out sound change when speaker is connected or removed.

Line Out is muddy and distorted with the speaker plugged in and just as clean as the headphone when I disconnect the speaker

Quote from: phatt on August 20, 2020, 08:46:13 AM
Q does the speaker switch off when you insert the headphones?
Phil.

Yes...the speaker is silent when headphones are plugged into the jack.  The other day I removed the jack entirely, soldered a jumper to make the output connection to the speaker leads, and it was still muddy, distorted, and low volume so the switching jack doesn't appear to be the problem.

With the jack in place, the speaker output is so poor and yet the exact same output running into headphones is so loud and clear.

FYI, the output at the "Line Out" jack sounds just like the speaker...muddy, distorted, and low volume.

Hi everyone,

First, thanks for allowing me to join you here.  I have done a lot of fx pedal building and recently completed the conversion of a Filmosound tube-based projector amp but a friend just asked me to look into his SS Traynor amp and it's the first time I have worked with one.

The basic issue is reduced output with a muddy tone and plenty of distortion through the speaker but loud clean output through the headphone jack.  I have verified that the speaker works fine by playing my Traynor YCV40 through it and, thanks to some suggestions on a SS Facebook page, I have also confirmed that the headphone switch/jack is working and that the DC offset is about 6mV.

Last night I found several pads on the PCB that were damaged or broken so I fixed and/or jumpered those and reflowed the solder on EVERY connection.  Low and behold, the speaker output was great for about 5 minutes of testing and then it abruptly switched back to the low mud and distortion.

One of the Facebook members suggested a test of the output transistors and I noticed that the 2 watt 330 ohm resistors and their adjacent diodes get very hot VERY fast and have actually discoloured/burned the PCB around them.  In addition, a light tap on those resistors with a wooden stick also caused a bit of the surface to flake off.

Now, I noticed another member was having heat issues with his TBM-25 and that was another reason why I requested to join this group since I figured he must have gotten those sorted out with your help.

I can attach a copy of the Traynor schematic for this amp once I figure out how to upload a PDF and I am hoping that you might be able to help point me towards a solution to this problem.  In the meantime, I *HOPE* the schematic is still available from the forum post here:

https://www.ssguitar.com/index.php?topic=4354.msg34812#msg34812

I look forward to your replies and thank you in advance!


- brad -