Rescue a TS-5

[elpops]

Hi,

I am fairly new to FX building and new to this board. I have modified some FX in the past, and built the Fulltone A/B box, and I have built and modified a few tube amplifiers in the past. My current diversion is to try to save a TS-5 Soundtank Tube Screamer that has a bad switch and either a bad output jack or some other source of buzziness.

I see a few electrolytic caps on the board that I bet need to be replaced, and could be the cause of the buzz. I have also read the article on tube screamers on the web, and I plan to do the 808 mods and upgrade all the tantalum and electrolytic caps to polyester film.

My question is, do you think there's a good chance that replacing those parts and dropping the FX board into a new enclosure with true bypass switching and off-board input and output jacks will fix my hum, or is there some obvious source of buzzing that I, as a noob, am missing?

Thanks in advance for your advice. I am thinking of building this into an enclosure with a rangemaster clone, with separate switches and LEDs, etc., but I want to get this thing sounding right first.

[Luijo]

First off, make sure it's not your power supply that's causing the buzzing. Try powering it up with a battery if you don't have a clean PS at hand.
The Ibanez "5" series pedals are notorious for unreliable switches and jacks. So a rehousing is an excellent idea since those pedals are quite good sound wise.
Keep in mind that if you're TBing this pedals that there are a couple of buffers that won't be needed and removing them will make your whole signal chain cleaner. Same can be said about the FET switching, you'll have to remove it from the line.
I bet after you get a lot of this circuitry out of the way your pedal will be much cleaner and quieter sounding.
What I'm not so sure is if the Rangemaster would be a nice companion to the TS as the latter suffers from weak low end and the former would only aggravate that. But who knows, maybe that's the kind of sound you're after!

[elpops]

Keep in mind that if you're TBing this pedals that there are a couple of buffers that won't be needed and removing them will make your whole signal chain cleaner. Same can be said about the FET switching, you'll have to remove it from the line.

That's encouraging news--I knew about the FET switching from the other article I read, and I plan to remove Q1 and Q2 from the board, and bridge the Q2 D and S, but thanks for reiterating. Which buffers can I remove? And can I remove the switch altogether by bridging the contacts on the board somehow?

[elpops]

Actually it looks like if I remove the FET switching it will cut out half of the circuit, including the switch and LED, and a bunch of transistors (which might be what you were talking about). So, that seems good. I just need to tweak some other values and hook it up to a good switch, I guess. But, stop me if that's wrong.

[Luijo]

You're almost there!
Can you post a link to the TS5 schem? There are a few on the net but would love to see the one you have at hand to check its accuracy. Is the one you have 100% correct with your pedal?
You'd be amazed at how simple the actual sound processing part of a TS circuit is. Most of the stuff you see on the board is just switching and buffering stuff!
Keep in mind you'll be needing a 3PDT switch for TB purposes. One third of the switch will be used for turning the LED on and off since the FET switching won't be doing it for you anymore.

[elpops]

On this schematic, basically everything on the bottom of the schematic, between the 'SW' marks, would be cut out of the circuit by tweaking the two 2SK30A transistors, right?

I have been reviewing a fullclone schematic and I see some parts substitutions I'd like to consider. One in particular that interests me is what appears to be the clipping diodes. The 808 spec has two 1N914s, but the fulldrive spec has one 1N4148, and a 1N4001 and 1N34A in series. Do you think this is important to replicating the fulldrive tone, and could I leave it as is and still get good (if different) results? Should the other transistors (2SC1815) be changed (to 2N5088) to match also?

I agree that once you remove the switching components the 808 circuit is pretty simple looking. I can't figure out why they didn't just use a true bypass switch in the first place. Seems it would have cost less to manufacture?

[elpops]

On re-reading the instructions from the geofex.com tube screamer page, from which this schematic was lifted, it seems maybe the switching FET on the left can be ignored, but the one on the right has to be pulled and jumpered?

[Luijo]

I see you don't have the original schem for the TS-5. You're working with the 808 schem which is not exactly the same.
They didn't use TBP back then because 3PDT switches were either unavailable or too expensive. Besides, FET switches offer noiseless operation and buffer your signal.
The different diodes of the fullclone version are there to achieve asymetrical clipping, supposed to enhance even harmonics and dynamics. Only drawback is that it lowers the max dirt available a little. Makes it cleaner sounding at the most extreme setting.
Changing the transistors won't make a world of difference and maybe you'll like it that way, doesn't hurt to try.
The actual TS-5 schem would really make things easier. Should be somewhere on the net.

[Sweetfinger]

TS-5, New paint job, old car...

FWIW I popped a "5" open many years ago and seem to recall that the TS-5 is almost a dead on duplicate of the TS-9, just in a crappy plastic housing. The board and layout are different, but the circuit is the same. It was at the height of Tubescreamer mania, and it behooved me to know exactly the differences between original 9's, reissues, 808's, 5's, and 10's. I was surprised that the 5 was the old circuit.

[msclford]

Here is the TS5 schematic available on the web. Not too helpful, but it's here.

[Luijo]

Thanks msclford!
It is indeed a repackaged TS 9, as far as I can tell. And just as Sweetfinger said, it's just the poor housing and switching making the difference.
So, you just have to remove Q1 and Q2. Then jumper the pads where the drain and source connections of Q2 used to be and the switching circuitry is removed.
I don't see no reason why not leave the buffer stages stages alone, but someone might have another opinion. I seem to recall it is the TS 10 that has a third buffer stage which can be safely removed.