Thanks for all the advice thus far, folks!  Here's a couple recordings of the amp.  The first one is the amp with no production effects.  I do turn on an OCD to give the amp more treble, as it is a little "dull" on its own.  The recording is rather long, so skip around to hear various tones.  I get to the overdriven tones near the end:

https://soundcloud.com/brianstewart-1/heathkit-ta-16-dry

Here's a recording with some reverb/compression/somethingelse that I put on with my DAW, just for fun:
https://soundcloud.com/brianstewart-1/heathkit-ta-16-with-effects

QuoteNow what was the remaining problem?

Well, there was dc on the output, so replaced that coupling cap, which solved that problem:


The main filter cap had a bulge in the end, so I replaced that as well.  I used what Radio Shack had on hand, which was (2) 2200ufd, 50v caps that I wired in parallel.  The original was 4000ufd, 50v:


That pic also shows the new bridge recto and the new 3 prong cord.

Now, the only things left are the tremolo and reverb.  I measured the voltages on all the remaining transistors, and they are good, so my guess is that the opto-coupler is bad in the trem. circuit.  Internet sleuthing revealed a good replacement, which I will order soon.   

There is no reverb tank, and I really don't want to spend the money on one yet, so we'll see what comes of that.  I also need to figure out the correct tank to get.  I have to match the input and output impedance of the circuit, correct?  Need advice here.

I also will be building a head cabinet for this at some point, as I have nothing else to put it in.

DC voltages on the output transistors:

Q9: Base: 19.15
      Emitter: 19.3
      Collector: 0 (connected to ground)

Q10: Base: 19.83
        Emitter: 19.3
        Collector: 33.8 (This is my "B+" voltage (rail voltage?))

So, my main "B+" voltage is about 4 volts less than the schematic, but my base and emitter voltages are about 1 volt higher than what is listed on the schematic.  However, the voltage drops across the base/emitter junctions are just about spot on with the schematic.

If this was a tube amp, I'd say these parts are functioning as they should!

Oh, the amp is also still plugged into the limiting bulb, so I suppose that is affecting the B+ voltage.  Is the correct term "rail voltage" here?  There is no negative rail, so...

QuoteI'm worried about those output transistors. My data says the 2N2148 is Germanium rated at 12.5W. It won't look good on most DVM diode test functions. I have no idea on the TA2577. There isn't much drive current available to Q10 so it needs high beta.

I tested both transistors using a basic "transistor test" using the ohms function on my DMM...maybe there is a better way to test these.  Also, I seem to remember learning something about "leaky" transistors, meaning that they sort of work, but "leak" current where they're not supposed to?  Could these transistors be "leaky", but still function somewhat?  I mean, I know they function, as I played my guitar through the amp and actually got some decent tones out of it...

QuotePity this thread was called new member and a question which means absolutely nothing.

Sorry about the title faux pas.  Some forums expect a formal introduction from new members before questions get answered.  I didn't see any kind of rule or introduction page, so I just went with what I thought would be the most effective.  I also searched this forum before I joined, and found several references to the TA-16 in a number of different threads, so I assume that this thread will pop up if someone searches the right terms.

If there is a moderator that could edit the title for better search-ability, that would be fine with me.

Thanks to all that are participating in this thread.

I'm off to measure voltages...

Both output transistors test bad using the ohm setting on my DMM.  One seems to test "worse" than the other, but that's kind of speculation on my part.  The PNP transistor fails all tests:  Emitter to base, base to collector, Emitter to collector, reversing the leads...I get conduction with all these tests.  The NPN transistor passed the emitter to base and base to collector test, but not the emitter/collector test.

Guess I need to hunt down some new transistors...

^Thanks.  I was pretty sure there shouldn't be much, if any DC on the speaker, but this is not something that I deal with when repairing tube amps! 

Yes, the amp distorts fairly quickly...maybe around 5 or less on the volume knob.  The distortion is a decent "crunch", though, so I' wasn't sure if this was normal or not.

The amp is fairly noisy, too...I'm sure it needs some new caps and maybe some of the old carbon comp resistors should be replaced.

I will test the output transistors today...

Well, I replaced all the rectifier diodes with a single bridge rectifier "chip"; got rid of the circuit breakers (one was bad) and added a mains fuse and installed a 3 prong power cord.  Plugged it into the leak light, which did not light up, and checked my voltages.  All were just a few volts off thanks to the leak light. 

I also measured for DC voltage across the speaker leads and had around 5 vdc, but that steadily dropped down to less than 3 volts, so I decided to plug a guitar in...and the amp worked! The normal channel works fine and the reverb channel won't work unless you jumper the footswitch jack.  I could not get the tremolo to work, and there is no reverb tank, but I did get a dry guitar signal with the jumpered jack.  I don't have a footswitch, or a "stereo" plug that the footswitch uses, so I'm totally sure that the tremolo doesn't really work, or if it is just that I don't have the proper plug.  More to tinker with I guess.

Once I get the reverb channel working, I think I will add a speaker jack & build a head cabinet for this thing, as the original cab was basically disintegrated when I received it...and I finished the process getting the chassis out :trouble.

I'll post some pics and sound clips if anyone is interested.  Thanks for your help!

Oh, I forgot to ask, is there an easy/quick way to determine the correct fuse to use in this amp?  Right now I just have a 3A fast blo fuse in there, but I know that is probably too large to do any good.

Two of the diodes in the rectifier were shorted, so I need to rebuild that before I go on.

I do have a bulb limiter and use it religiously.   I also have the schematic for the amp in question.

I will post results as soon as I have them...

There are no fuses, just circuit breakers...and they are not popping.  I can't be certain that they are functioning correctly however.  This amp is in pretty rough shape.

Whoops, typed too fast.  I disconnected the SECONDARY wires from the amp!!  So, I'm basically just measuring what the PT is doing.  120vac on the primary & 29vac on the secondary.

That makes more sense, right?!  Sorry... xP

I got to thinking a little bit and decided to disconnect the primary wires of the PT from the amp and measure that way.  Doing this, I get 29vac.  The highest DC voltage that the amp uses is 39 volts, so I guess my PT is probably good and I have a shorted component in the power supply?

Also, this amp has circuit breakers instead of fuses, and they seem to be a little suspect.  I'm thinking of jumpering across them, one at a time, to see if that helps.  Sound too dangerous?

Thanks again!!

Hello SSGA folks, new member here.

My name is Brian and I am a luthier/guitar tech/amp repair tech.  I went through a 2 year "electronic music technology" course about 20 years ago here in Red Wing, MN.  I also took a guitar repair course and have been a luthier building folk harps for Stoney End Harps for the past 17 years.  Recently I've decided to quit the harp business and focus on guitar/amp repair.

My main focus has been on tube amps, but I'd like to get better at repairing solid state devices, as there are not too many folks around my region that do that.  Needles to say, I'm a little rusty on my solid state theory, although I have all my notes/text books from school and had good teachers, so I'm hoping to get quickly back in the saddle so to speak.  Also, I've always been into tube amps, so I have decent trouble-shooting skills/equipment and know how to solder quite well.  I have fixed several pieces of solid state gear over the past several months as well, and have some power amps coming in this week.

Anyway, yesterday I picked up a couple old, not working guitar amps just to mess around with.  The one I will ask a question about here is a Heathkit TA-16, and it mainly concerns getting some new parts.  So...

1.  The power transformer seems to be bad.  The 120vac is getting onto the primary, but I only have 3.4vac across the secondary.  I know I can't get a direct replacement for this PT...or at least that would not be cost effective at all, so is it possible to find a suitable substitute?  How would I go about finding this?

2.  As you probably know, these amps came as kits for the customer to complete.  This one is put together pretty well, but the bridge rectifier circuit is pretty messy.  I think I'd like to replace it with a chip, if possible.  What do you think of that idea?  Would I be better off just buying the correct diodes and rewiring that way?  What chip or diodes would you recommend?

Once I get power on the board, we'll see where I can go from there.

I have accounts with Mouser, MCM and Parts Express, fyi.

I've really enjoyed browsing through the forum and I look forward to being a contributing/learning member.

-BrianS