Teisco Spectrum 5 Reissue

[solderburn]

Pictured here are my recently acquired 1990s Teisco Spectrum 5 Reissue and Fender Princeton Reverb Reissue.

I love these, one is an oddball and the other is a standard, throw in a Surfybear toolbox build and it's a done deal.

The guitar is a gift that i just received from a very good friend, such a generous and kind guy, i'm lucky to know him, I've known him since high school days. I'm his guitar tech and i do a lot of work for him for free so he surprised me with this amazing guitar that could only be dreamt up and produced in Japan. I love everything about it, the Pearl White paint job, spring loaded selector switches (like an old dishwasher), the aluminum dials, crazy headstock that looks like it's right out of the Jetsons. The electronics match the radical look, the stereo outputs are wild, the treble side of the pick-ups are split from the Bass side of the pick-ups, so i can have them going to different amps with different effects, like reverb and tremolo drenched low strings, and fuzzed out echo on the treble side, just wild. The switches allow any combination of pick-ups, and i'm still not 100% sure what the the red and orange switches do, sounds like it's out of phase and a treble cut. PUs seem like they have a high output and cover a wide spectrum of frequencies, appropriate for a guitar named "Spectrum 5".  I could only find vague and incorrect information regarding what the switches do, i don't have a manual, and i assume they were only printed in Japanese.  I'm hoping you folks can help me run some diagnostics to see what exactly the switches do, maybe I can do some tests with a multi-meter and take some pictures under the hood/bonnet to get a better idea what specifically is going on in this guitar.

The FSR Princeton '68 Reverb Reissue is a thing of beauty, cosmetically and practically. Found it on Craigslist for a price i couldn't pass up. It's such a perfect amp. This one has a G10 Greenback speaker that makes it a little different than what is traditional, sounds like it has some more midrange, still very Fendery though.

[newey]

Nice rig! But tell us about the reverb unit, please.

As far as what the switches do, since a look under the hood will involve destringing it, probably best to perform the screwdriver "tap test" first just to be sure which coils are active in which switch positions. Then make a chart so we can zero in on the unknown ones. The tap test won't tell you about phasing, but that should be apparent from the sound.

You can use the multimeter at the output jack to check for resistances but that won't tell us about a treble cut or phasing. The technique is more useful for troubleshooting problems. We could use that info to figure out the resistances of the pickups and the pot values, but that's not what you're after here.

[col]

Hi solderburn,

The controls, as described here:

www.makenmusic.com/products/eastwood-guitars-tdr-series-spectrum-5-pro-metallic-red-teisco-tribute-model-offset-electric-guitar-new

Here are the Control Knobs: - Green = (Center/Pair) - Yellow = (Rear / Pair) - Orange = (Phase) - Red = (Phase) - Blue = (Front/Pair)

[solderburn]

Thanks newey and col!  

newey, I'm gathering the info from the tap tests this morning, drinking some coffee as this is not as simple as i wished. 

...And that Reverb unit is a kit that i housed in a Harbor Freight tool box.  The kit is was designed and sold by a fellow named Bjorn Isheden, it's essentially a copy of a Fender 6G15 reverb unit made famous by Dick Dale, but this circuit is different in that it utilizes MOSFETS instead of valves to drive the real spring tank, allowing it to be housed in a substantially smaller enclosure than Fender's original circuit. It's got an amazing drippy, sploinky tone when played with a palm mute.  It nails the sound of one of my favorite bands, The Astronauts.  The kit is no longer made since the one man operation has grown a bit and now they sell ready made pedals. Feel Free to remove this tangent into a different thread if you deem it better to have it's own spot. Thanks. Building Surfybear kits is what made me start soldering and got me on my path to do simple wiring on guitars, which led me to this fabulous community. It's awesome to grow here.

 




You might notice that some of my SurfyBear builds have an extra knob on the far left, it's a "color switch", basically a rotary switch that selects between capacitors of different values to bring out different resonant frequencies which accentuate the drip in different ways.  Fun stuff! 


col, thanks for your input.  I saw that site but there are a few issues, this model is a reissue by Teisco, not by Eastwood, and i'm not sure how accurate their version is.  I noticed the switch colors are not in the correct order on the Eastwood, specifically the yellow and orange are reversed. Another thing is, even considering that they might just have a different color switch the but the functions would be the same, I'm still not observing what they describe.  And it doesn't mention what's going on when none of the switches are engaged, intuitively it would be nothing, but when i do a tap test i hear N+B(!).  So i will continue to investigate.  Also I don't understand what Eastwood means when they say "Front/Pair" ect.  I'm confused what they mean by pair.  

[col]

"Pair", I expect, refers to each of the three pairs of paired pups: bridge, middle and bridge pups.

Edit: And, I expect (OK, guess) that even if the colors/order of the switches are changed, the actions of the set of five switches as a whole will be unchanged.

[solderburn]

Thanks, col!  I wasn't sure if that's what they meant by pair, since I'm not observing the functions that Eastwood is describing. And i also assumed that they had merely changed the color order but not the function, even still, things aren't lining up.  One thing is for sure, I'm very confused, and looking forward to figuring out what is actually going on.  I will be posting my 'data' soon. 

[col]

I just finished watching this video - they describe the function of each of the buttons. Maybe it will help you.

[col]

I came across some other videos which suggest different switching - I think they are for the '5', whereas yours (I think) is the '5 Pro'. If I am correct, the switching with '5' is: neck; neck-middle; middle; middle-bridge; and bridge (no phase options). With the '5 Pro', the first three switches control the three pups individually (or can be combined), and the last two switches are phase controls. You will note, the switch colors match your guitar. Edit: Oops - no they don't. I am more confused now.

[solderburn]

Thanks, i appreciate your help, col.  Sorry for taking up so much of your time. 

I've watched both of those vids before. there's some good info but i'm still not clear about the function of the red switch (not the stereo switch), and the videos don't mention what's going when none of the switches are engaged.

Also, i thought phase cancellation would simply cause the out of phase tone, not totally cancel the output.  I have a lot to learn.  

Indeed, confusing AF. Me too. I will post my data table soon, then later I'll get some guts shots.    And i think the "Spectrum 5 Pro" is the Eastwood version, where as i have the 1990s Teisco reissue, so mine is just a Spectrum 5, same as the first video you shared.

[col]

No, of course you are correct that out of phase will not (should not) totally cut the output. I did note that in the video at the time, but then forgot about it.

Well, good luck. I look forward to what your testing shows up.

[Yogi B]

Jul 10, 2021 14:30:58 GMT -5 col said:

No, of course you are correct that out of phase will not (should not) totally cut the output.

I agree, I think that was misspeak (or misunderstanding) and the silence when selecting the bridge & neck is due to a weird wiring issue.

Jul 10, 2021 14:21:24 GMT -5 solderburn said:

And i think the "Spectrum 5 Pro" is the Eastwood version, where as i have the 1990s Teisco reissue, so mine is just a Spectrum 5, same as the first video you shared.

I think the wiring schemes of the Eastwood & the reissue featured in the Ishibashi Music videao are (trying to be) identical though, the difference is that the Eastwood version has regular slide switches rather than radio buttons, and has the dead positions eliminated. Though it's unclear whether the pickups are combined in parallel or in series, though from the videos it sounds like parallel — which is unfortunate as I would've hoped it was series as that would be a little closer to the original wiring...

Apparently Kawai (who acquired Teisco in '67) produced at least two reissues: one with the switching scheme later since copied (and fixed) by Eastwood; and another which accurately reproduced the original '60s wiring.

The originals also had radio buttons, primarily designed such that one button would be pushed at once, but have different wiring as can be seen in the following video (from the last time the Spectrum 5 was discussed around here).

Jun 22, 2014 19:10:48 GMT -5 edvard said:

I have a friend who is wanting to do a restoration after the previous owner gutted it to his liking.

Here's a demo video that shows all the myriad switch combos, and what they do to the sound:



Does anybody have a wiring diagram, or even a decent high-resolution gutshot that I can trace the wires from? I'd also love to try doing the same wiring on a "project guitar" at some point, but I have too much else on my hands at the moment.

As you can see in this shot of the super-rare plexi version: joelasqo.com/blog/wp-content/uploads/2013/08/Henry-Kaiser-1.png
there are mini-transformers between the pickup positions. Anybody ever seen anything like that used in a guitar?

Thanks

(The transparent version that Kaiser is holding is one such reissue with the '60s wiring scheme.)

I found this article in Japanese about the reissue with '60s wiring from which I'll post the relevant section below (Google translated and slightly tweaked):

Therefore, for the sake of explanation, I will quote Kawai's promotional materials at the time of reproduction.

There are 6 PUs with numbers from 1 to 6, which is true.

• 1-3-5 from the neck on bass string side
• 2-4-6 from the neck on treble string side

I think it was, but I'm a little suspicious because there are no notes left on this point. Perhaps it was the exact opposite order ... but if you look at the combination below, I think it doesn't really matter.

Yogi B's note: The above designation is wrong (see the instruction sheet I found a few posts later). From neck to bridge, the pickups are numbered: 1-2-3 for the treble side; and 4-5-6 for the bass side

In any case, it is a model that can only be used by selecting from this combination of presets.

No.1 PU1 to 3 and PU4 to 6 are ON (low cut sound)
No.2 PU1 to 3 and PU4 to 6 are ON (out-of-phase sound)
No.3 PU3 and PU6 are ON (single coil sound)
No.4 PU1 & 3 and PU4 & 6 are ON (normal humbucker sound)
No.5 PU1 to 3 and PU4 to 6 are ON (high power humbucker sound)

This seems to correlate well with the video, I assume the "low cut sound" is making use of the transformers that can be seen through the acrylic version. However I'm unsure what exactly the "out-of-phase out sound" is, well it is all three pickups with one of them out of phase, but I couldn't say which one.

---

Edit: Hang on while I figure out a schematic for the '60s wiring, to better explain how I think the switches might interact...

[thetragichero]

channeling gumbo to derail the thread here, but what's the big fender? super six?

[solderburn]

Thanks Yogi B!  Lots of great info!  

And thetrajichero, good guess, it's a 70's Fender Quad Reverb, it's like a twin with 4 12s., immensely loud and clean.

[solderburn]

Preliminary observations, baffling. 
Multimeter reading for all switch settings in mono are 1.41 k ohms! All settings on the stereo output one are 2.82, and stereo output 2 are 2.77.  I made sure volume and tone were all the way up. 

Tap test:

Individual switch settings grouped here.
Blue =     NMB  (sounds muddy)
Green=    NB     (less muddy)
Yellow=    B      (possibly OOP, sounds more trebly than the green or blue)
Orange=   NMB  (probably OOP)
Red=       NMB   (possibly OOP, not as noticeable as orange)

Rest of settings:

Blue+ Green =  N  (thick, but not muddy)
Blue+Yellow  = no signal (output is super low, about 5%, i guess)
Blue+Orange = N  (sounds the same as blue and green)
Blue+Red      = NB  (sounds very similar to the other blue settings, but slightly thinner, not much)

Green+Yellow=    NB  (balanced, not twangy as i would expect)
Green +Orange= NMB  (OOP)
Green+Red=       NMB  (very similar to green alone, but slightly clearer)

Yellow+Orange= B  (similar to yellow alone, but slightly thicker)
Yellow+Red=      NB (thicker than yellow+orange)

Orange+Red = NM (definitely OOP)

Red=           NMB  (sort of a strat quack, but not pronounced)

Blue+Green+Yellow+Orange= (loud output, thick sound, but not muffled)

Blue+Orange (sounds the same as red+green)

No switches pushed down= MB (sounds the same as just yellow)

Interesting findings. I'm still confused though. 

Also these magnets are really physically strong, seem to have a lot more pull than any other guitar i own. 

Obviusly there are more combinations that i didn't go through, so much going on, i can see why there's not more info.  So far the best info compiled is that the thread that Yogi B posted. 

Thanks all for your help and time! I will have a guts shot later.  

[Yogi B]

EDIT: This was cross posted with solderburn's reply above and therefore is not based upon those readings, something at least somewhat different must be going on.

FURTHER EDIT: with the benefit of additional hindsight, the below is quite wrong so I've spoiler-ed it!

SPOILER: Click to show

Jul 10, 2021 15:03:16 GMT -5 Yogi B said:

I assume the "low cut sound" is making use of the transformers that can be seen through the acrylic version.

After making a first attempt to draw this up, I've now changed my mind.

(And now I know the reason behind why the wiring phase switch(es) is a potentially problematic issue.)

If the orange switch changes the phase of one of the pickups how many switching poles would it need? Normally two per coil, so to independently switch the phase of both coils (which in stereo mode will be going to different outputs) you'd need a four pole switch.

As far as I know, radio button switches were only ever DPDTs, so how was this done in the '60s wiring? I think that's what the transformers are for!

In the below schematic I've assumed the phase switching applies to the bridge pickup as it was easier to draw, (whichever it is, it's one of the two pickups that is selected by the green switch, as per the video that edvard shared):

[Yogi B]

Jul 10, 2021 16:27:09 GMT -5 solderburn said:

Multimeter reading for all switch settings in mono are 1.41 k ohms! All settings on the stereo output one are 2.82, and stereo output 2 are 2.77.

Well that answers the question in my schematic as to whether the two channels are combined in series or parallel. It's parallel!

Though it is odd how all positions give 1.41 kilohms. Maybe I'm still wrong about what those transformers used for, and in fact they're used to isolate the stereo outputs?

I made sure volume and tone were all the way up.

I thought they were two volume controls (one for each of the outputs), no?

---

I'll see if I can adjust my schematic to better fit your test results.

[solderburn]

Yogi B, you are a genius. Thanks for all of that!  So cool of you! 

The dials re volume and tone, for sure, even though they both say volume of the ring with the numbers, i suppose it doesn't reallt matter for the japanese market.  I assumed the same thing until i plugged it in. 

[solderburn]

Can someone please tell me what are the squares above the neck and middle treble PU?  They almost look like mini transformers, the first time I've seen somethig like that in a guitar. 

[thetragichero]

those 'squares' are transformers

[Yogi B]

Jul 10, 2021 16:57:20 GMT -5 solderburn said:

The dials re volume and tone, for sure, even though they both say volume of the ring with the numbers ... I assumed the same thing until i plugged it in

Apparently it's both 1V 1T and 2V. I've found an instruction sheet from a now defunct ebay listing (and, as I later found out, this reverb listing):

As far as what Google translate can make out, the section in the bottom left (and continued on the top right) claims roughly the following:

1. In monoaural
   PU1 to 6 is sent to 1V 1T output from jack 1. The knob on the head side is volume, the knob on the end side is tone. (Although the plate on the neck side is written as VOLUME, it is not an error.)
2. In stereo
   PU1 to 3 as selected by the 5-unit switch uses the knob on the end side as 1V and is output from jack 2, PU4 to 6 uses the head side knob as 1V and is output from jack 1, and there is no tone. In other words the treble side is V2 & J2, and the bass side is V1 and J1

Also of note is section 1 subsection 2 which describes the function of the switches. The functions are the same as were repeated in the Japanese article I translated earlier, however the introduction includes something along the lines of the following:

Please avoid pressing two buttons at the same time. We cannot guarantee operation.

---

solderburn, your photo's look great! I'll see what I can trace...

[solderburn]

Thanks thetrajichero.  If you don't mind answering my stupid novice questions... What kind of transformer is it? Electromagnetic?  What is the typical function in a guitar circuit? 

[solderburn]

Yogi B, that's some exceptional detective work/research.  I'm excited to be getting such an accurate understanding of this odd design. 

[Yogi B]

solderburn, I think I'm getting there with understanding the switching, but could you confirm something? (To make sure I'm not being daft.)

In stereo mode, in most positions where only a single switch is pushed (blue, green, yellow, or orange) I think you should get the bass strings from jack 1, and the treble strings from jack 2. (As it states on the instruction sheet.)

However, it looks like with only the red switch pushed things would be correct for the neck and middle pickups, but for the bridge pickup they'd swap: you'd get treble strings from jack 1 & bass strings from jack 2. So overall you'd get a mix of all strings from both jacks, is this correct?

In other words: for both of the output jacks when in stereo mode, please could you do the tap test for the 6 individual pickups with only the red switch is pushed?

(Also, I now know my schematic from above is quite far from the mark, not just series wiring, but actually a clever mix of series & parallel. I also had the transformers entirely wrong, as evidenced by the fact they don't have a centre tap.)

[solderburn]

Jul 10, 2021 21:37:00 GMT -5 Yogi B said:

In stereo mode, in most positions where only a single switch is pushed (blue, green, yellow, or orange) I think you should get the bass strings from jack 1, and the treble strings from jack 2. (As it states on the instruction sheet.)

However, it looks like with only the red switch pushed things would be correct for the neck and middle pickups, but for the bridge pickup they'd swap: you'd get treble strings from jack 1 & bass strings from jack 2. So overall you'd get a mix of all strings from both jacks, is this correct?

 Yogi B, you are spot-on with your assumption.  I just did a tap test in stereo, lo and behold, you are certainly correct!

[Yogi B]

Jul 10, 2021 22:08:20 GMT -5 solderburn said:

Jul 10, 2021 21:37:00 GMT -5 Yogi B said:

In stereo mode, in most positions where only a single switch is pushed (blue, green, yellow, or orange) I think you should get the bass strings from jack 1, and the treble strings from jack 2. (As it states on the instruction sheet.)

However, it looks like with only the red switch pushed things would be correct for the neck and middle pickups, but for the bridge pickup they'd swap: you'd get treble strings from jack 1 & bass strings from jack 2. So overall you'd get a mix of all strings from both jacks, is this correct?

Yogi B, you are spot-on with your assumption.  I just did a tap test in stereo, lo and behold, you are certainly correct!

So, now for the million dollar question: is that intentional, or is it a wiring error?

I can't see any reason why it should be wired that way, but I could be missing something. We'll wait and see if anyone else has any ideas.

---

Alright, so here's the schematic I have:

With only one switch pushed, for each 'channel' this gives:

Single Switch Pushed	Pickup Selection
BLUE	B × M × N
GREEN	B + N
YELLOW	B
ORANGE	B + ~M + N
RED	B × R × (N + ~M)

Where: "R" is one of the 510 ohm resistors; and each selected pickup belongs to that 'channel', with the exception of the bridge pickup when the red switch is pushed (as noted above).

The combined settings will have to wait until tomorrow, I think they mostly agree with the selections you noted earlier, however with a only quick overlook there may be a couple of discrepancies.

[solderburn]

Yogi B, your understanding of these things is outstanding, thanks so much for taking the time to unravel the mystery of those switches!  I knew it was more complicated than what the videos where saying.  It's also interesting to see that the original manual "warns" against selecting more than one switch. haha

[col]

So, for what are the isolation transformers used? Is it to prevent the the two sets of pickups from loading each other and reducing bass frequencies?

Edit: Oh. And the two 510Ω resistors - their purpose?

Edit 2: Oh, I see, I think. The transformers allow the stereo option to function.

Edit 3: re: Edit 2 - maybe I was right the first time. The two 'channels' are fully separated anyway. Perhaps I should just wait for someone who knows what they are talking about.

[Yogi B]

Jul 11, 2021 4:25:21 GMT -5 col said:

So, for what are the isolation transformers used? Is it to prevent the the two sets of pickups from loading each other and reducing bass frequencies?

In one aspect, the exact opposite — which was my original thought before I started talking myself out of it, by thinking about how the phase switching would work.

Oh. And the two 510Ω resistors - their purpose?

In conjunction with the transformers they increase the cutoff frequency of a highpass (low cut) filter, which is formed from having an inductor (half of each transformer) to ground.

Without the resistor, the cutoff frequency ought to be lower than the fundamental frequency of the low E (so as to have little to no effect on the signal), but ought to be significantly higher when the resistors are present.

This also leads us to a realisation about the pickups, they must be low impedance; otherwise 510Ω would do very little to shift the cutoff frequency.

And so the second purpose of the transformers is revealed: to convert the low impedance signal from the pickups into a higher impedance signal, closer to that of a normal guitar (though still comparatively quite low).

[newey]

Jul 11, 2021 0:06:35 GMT -5 Yogi B said:

With only one switch pushed, for each 'channel' this gives:

Single Switch Pushed	Pickup Selection
BLUE	B × M × N
GREEN	B + N
YELLOW	B
ORANGE	B + ~M + N
RED	B × R × (N + ~M)

Where: "R" is one of the 510 ohm resistors; and each selected pickup belongs to that 'channel', with the exception of the bridge pickup when the red switch is pushed (as noted above).

How is this consistent with Solderburn's resistance readings? (I was already mystified by his readings anyway, but this further confuses me.) How can all the mono switch settings be the same if pickups are combined versus selected alone?

[col]

Jul 11, 2021 8:41:15 GMT -5 newey said:

Jul 11, 2021 0:06:35 GMT -5 Yogi B said:

With only one switch pushed, for each 'channel' this gives:

Single Switch Pushed	Pickup Selection
BLUE	B × M × N
GREEN	B + N
YELLOW	B
ORANGE	B + ~M + N
RED	B × R × (N + ~M)

Where: "R" is one of the 510 ohm resistors; and each selected pickup belongs to that 'channel', with the exception of the bridge pickup when the red switch is pushed (as noted above).

How is this consistent with Solderburn's resistance readings? (I was already mystified by his readings anyway, but this further confuses me.) How can all the mono switch settings be the same if pickups are combined versus selected alone?

Ah. I believe this is because Solderburn was measuring the resistance value of the inductors, not the pups themselves. It is not possible to measure the resistance of the pups from the jack socket.