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Modding a Heathkit TA-27

Started by TheSargent, May 08, 2017, 10:53:24 PM

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TheSargent

Hey all. I've got some entry level electronics experience, having built and wired a few guitars and pedals, and I'm trying to mod out this amp. As it stands the reverb unit itself is missing and the pot is disconnected leaving the regular channel to hum uncontrollably. (The line reverse channel has a bit of noise, but much more manageable). Like many others have experienced with these amps, the tremolo kinda sorta works but not in a way that makes it useful. I understand that these guys are basically hi-fi amps, so I was thinking that I could replace the power cord with a three prong, replace the caps, swap the three-way dpdt switch with a simple on-off, and remove the reverb and trem sends altogether in favor of an effects send with which I could use a distortion pedal, tremolo pedal, reverb pedal, etc. Do these mods sound feasible, or is there a better way to accomplish my goal?

http://ctgelectronics.weebly.com/uploads/3/1/6/6/3166248/ta-27_schematic.pdf

That's the schematic for reference. I'd also appreciate some guidance on where the components I'm looking for are as I'm new to reading schematics on this scale. Thanks in advance!

Enzo

I bet you can find the manual for this.  it was a kit, the manual was to build it with.  But it includes the board layouts as well as the schematics, parts lists, etc.

galaxiex

#2
Welcome Sarge!

There is a manual for that amp available here >>> http://www.vintagemanuals.com/index.html  for nominal cost.

Reverb tanks are relatively cheap, and if it was my amp I'd try to "restore" it electronically and get it all functioning again.

The tremolo optocoupler is difficult to find, but we don't know yet if yours is bad.
I have a TA-16, same amp as yours but with a non-effect channel and 2X12 speakers.
The tremolo on mine works/sounds pretty good.

I understand your desire for an effects loop but I personally don't like them.

There is a thread here >>> https://www.ssguitar.com/index.php?topic=2762.msg20129#msg20129
that describes an input buffer and is what I consider a "must" for these amps.

Cheers!

Edit; there is a reverb tank available here >>> https://www.amplifiedparts.com/products/reverb-tank-mod-4fb3a1b


If it ain't broke I'll fix it until it is.

TheSargent

Thanks a ton galaxiex! I'll take a look at that manual and see what I can do!