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Author Topic: Tech 21 - Trademark 60 Problems!! Any Help Here?  (Read 12399 times)

Rusty Chops

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #15 on: May 09, 2014, 12:04:04 AM »
I've used a ton of Tech 21 stuff over the years.

A common fix on the Trademark 60 is to patch around the channel switcher with a 1/4" cord in the effects loop (out the pre - into the power). You don't even need to select with a footswitch.

See if that restores the sound.

I've seen this happen on TM 60's with a lot of time and humid environment exposure.

DrGonz78

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #16 on: May 09, 2014, 06:24:57 AM »
Yeah I would have tried the patching of the effects loop just to rule it out. Since this fault is occurring in a timed fashioned then maybe it is related to the thermal cutout issue. However, Roly asked many many questions that were never answered. I mean was the heat sink getting hot? Not much troubleshooting going on in this case.
“A person who never made a mistake never tried anything new.” -Albert Einstein

bogner100b

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #17 on: May 21, 2014, 03:45:13 PM »
Hi Guys - So I replaced the output chip ( LM3876T), fired it up........played for 5 minutes...and same thing POWER DROP out.   :-[

joecool85

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #18 on: May 22, 2014, 06:58:54 AM »
You should really go through the thread and test the things folks have asked you to. Once you provide answers to those questions, we will be able to help.
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Roly

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #19 on: May 22, 2014, 07:52:27 AM »
Chik-chik BOOM!

... bugger ... missed.



I'm not having a good day.  An old friend turned up with his 'puter, can't access anything, wants to unload his large collection of photographs.  Now he's a really nice guy, great drummer, good blues harp player, but he's a total techno-illiterate.

Fire it up and this old clunker is asking for Windows authorisation.  WTF?

Turns out the 14yo son of his new girlfriend has been having a go, after all aren't all teen dweebs Masters of Computer Science?

I've been telling him for some years now to disable the password protection.  He doesn't need it and the potential downside...

Give it a badly needed clean and switch to a known good bootable HDD of mine, and everything is fine, so the basic hardware seems okay.

Alright, out with his HDD and into one of my machines as a slave.  It's so full you couldn't get a prawn cracker on there, but all goes well until I try and access his data folders and ... it's all compressed and encrypted!  If I had warned him once I have warned him a dozen times over several years, but no, here we now stand at last, knee deep in the ordure.

It appears that the only way in is to put his HDD back and try and get his machine to boot.  Replace dead CMOS battery and reassemble.  It wants an Internet connection to do the validation, but seems to be at such a primitive stage of booting that it won't recognise any of the connections I offer; looks like it will only work with his old ADSL connection (which got left at his previous house blah blah), and which, of course, I don't have.

Waste another hour trying to get some sense from Microsoft's phone robot, or talk to an actual person, then the working day ends and that door closes.

He tries ringing the 14yo to see if we can get some sort of handle on what he may have done to get into this situation but gets the girlfriend who tells him, loud enough for me to hear, that he should "take it to a real technician".

A working lifetime on a wide range of electronics and unbogging hundreds of computers flashes before my eyes and I'm filled with a homicidal rage, which I somehow manage to contain because she is not actually to hand for a spot of strangulation.  He is in this situation because he a) failed to follow my repeated advice, and b) let a 14yo play with the machine containing his valuable collection of photographs.

{and lightning bolts have nothing on hormonal teens when it comes to turning a functioning computer into smoking rubble.  One red-faced mom called me to the family computer which now had highly gynecological wallpaper locked in and was literally trying to call Nigeria long-distance.}

After four hours I intended to use sorting a problem on one of my own computers, having to accept that this is one of the 1% of jobs I can't fix due to the "monkey grip" or keys-locked-in-the-car nature of the problem, I get grievously insulted after providing a couple of hundred dollars worth of skill at the drop of a hat for nothing.   :trouble


I think I'll just have a little lie down now, maybe watch some garbage TV...   :duh



Quote from: DrGonz78
Not much troubleshooting going on in this case.

Fixed.
If you say theory and practice don't agree you haven't applied enough theory.

nashvillebill

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #20 on: May 22, 2014, 07:58:20 AM »
You should really go through the thread and test the things folks have asked you to. Once you provide answers to those questions, we will be able to help.

We cannot overemphasize this enough.  If your car doesn't start one morning, do you automatically replace the engine?  Of course not...you would (hopefully) go through some diagnostic steps--does the starter motor turn over, is there gas in the tank, etc.

Same way with amps.  Sometimes we open up the amp and the problem is obvious, but often it isn't.  If the problem isn't obvious, we typically start going through various troubleshooting steps--we don't just start replacing parts.  We measure voltages, trace the signal through the amp, sometimes we observe the signal on a scope.  The goal is to determine where the problem lies, then replace only the defective part(s).  It's the most efficient, most cost-effective way.

Merely replacing parts can sometimes create even more problems.  I've got a friend who sells used stereo equipment and from time to time he brings stuff over to me to repair.  Often, he's tried to fix it himself...but his repair skills consist merely of unsoldering parts and replacing them, he has little technical knowledge and no troubleshooting skills.  Usually, I've found that he has replaced perfectly good parts.  He's also inadvertently soldered transistors in wrong, lifted PCB traces, and had cold solder joints.  In other words, by attempting to fix an amp with blind-luck parts change-outs, he's caused more problems than he's solved.

QReuCk

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #21 on: May 23, 2014, 07:20:39 AM »
As an owner of a Tech21 Trademark myself, I can confirm what Roly suspects from the design: they get really hot after a good usage. Never had a problem with mine (which actually is a 120 and is monted vertically with a little more vents in it).

anyway, most important thing to do is to LOCATE where the problem lies. Basic trouble shouting for an amp which has such a complete set of connexions on the back panel would be this:
1° try connecting the preamp out (either effect send or Sansamp out) to another power amp/combo amp/whatever amplified thing. Ear if the preamp is good.
2° try feeding the poweramp with any preamp you can find (effect send or preamp out of another guitar amp or even a mp3 player into the effect return of your amp) see if power amp is good
3° try bridging effect send to effect return with a 1/4 cable see if the effect loop switching and connexions are good. Make this try with and without footswitch plugged in.
4° Also try with and without reverb activated.
5° If you have access to an external speaker, also try with one.

Time being a factor, especially on an amp which by design heats a bit more than most others, we can safely thing temperature is a factor. Well temperature is a factor for purposelybuilt thermal cut out, but it is also a factor with bad connexions (connectors OR bad solder joints). You know things tend to move/change dimensions a bit when temperature increases don't you? It isn't that big a stretch to assume a bad connexion may have turned into an unintended thermal cut out. And is the amp farts instead of just going silent, then I would thing an unintended thermal cut out is more likely than a purposely built one. Just saying...

Roly

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #22 on: May 23, 2014, 09:53:54 AM »
An early thought was that in this particular setup there is something like an extra cab which is resulting in too low a load impedance and thus excessive amp heating, triggering the internal chip protection, but the question never got an answer. 

I'll now return to my bench where I'm trying to fix my Crystal Ball. 
If you say theory and practice don't agree you haven't applied enough theory.

bogner100b

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #23 on: June 24, 2014, 12:25:37 AM »
Been away for a bit but to try and answer a few questions.

1) There is no other cabinet involved with this amp which would lead us to assume that we are dropping the impedance.

2) The amp is still functional it just as noted in other posts fartsquirts out.

3) Turn back on in 10 second and we're good for while then she farts again.

My question is whether or not the PT is shorted out?

Is there a cap that needs replacing?



Roly

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #24 on: June 24, 2014, 05:47:51 AM »
Quote from: bogner100b
My question is whether or not the PT is shorted out?

The very few facts hat we have been given to go on are not consistent with that diagnosis.  No.

Quote from: bogner100b
Is there a cap that needs replacing?

Please see this post.
If you say theory and practice don't agree you haven't applied enough theory.

DrGonz78

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #25 on: June 24, 2014, 07:37:11 AM »
Was this heat related? I am not sure if you answered the question if the heat sink was getting hot? When you first changed the chip you said the amp did play for about 5 minutes. Now it is back to 10 seconds and farts out, turn off then on, 10 seconds farts out again.

This is not going to be easy to fix without a schematic and we will never get one for this amp. Best idea is try to understand the datasheet for that chip and how they use them in circuits. Without testing voltages we definitely can not conclude it's anything related to the PT. Does this amp have power amp in or preamp out jacks? Have you established this testing method in relation to this post?>>>

I've used a ton of Tech 21 stuff over the years.

A common fix on the Trademark 60 is to patch around the channel switcher with a 1/4" cord in the effects loop (out the pre - into the power). You don't even need to select with a footswitch.

See if that restores the sound.

I've seen this happen on TM 60's with a lot of time and humid environment exposure.
“A person who never made a mistake never tried anything new.” -Albert Einstein

J M Fahey

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #26 on: June 29, 2014, 01:46:23 PM »
Been away for a bit but to try and answer a few questions.

1) There is no other cabinet involved with this amp which would lead us to assume that we are dropping the impedance.

2) The amp is still functional it just as noted in other posts fartsquirts out.

3) Turn back on in 10 second and we're good for while then she farts again.

My question is whether or not the PT is shorted out?
No.
Quote
Is there a cap that needs replacing?
How should we know?
None of your data points to that.

Roly

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Re: Tech 21 - Trademark 60 Problems!! Any Help Here?
« Reply #27 on: July 01, 2014, 10:49:59 AM »
 ::)


If you say theory and practice don't agree you haven't applied enough theory.