A new Ebarn find; Teisco (Japan) Checkmate 17 or CM-17

[smackoj]

Searching the Ebarn nowadays is quite a bit more challenging than it was five yrs ago. Now the number of items available that I have an interest in,  (old amps and tools) has grown huge in comparison, but almost all sellers are peddlers working from home with hundreds if not thousands of items listed for sale. And that has greatly increased the prices they ask for vintage pieces. That is why I was delighted to negotiate a great price on this cool and dainty Teisco amp. Made in Japan  a while back (I haven't dated it yet) with small and meticulous hand construction. It is a really nice 'golden days' tube amp era find. It is a small amp but the builders were smart and cool enough to put a nice alnico 10" speaker in it. Couldn't be happier about it.

I have a schematic which is darn hard to find on the web, so maybe Doug would want to make a place in the Schematics Library for Teisco? Just a thought, no pressure.

[sluckey]

I have a schematic which is darn hard to find on the web, so maybe Doug would want to make a place in the Schematics Library for Teisco? Just a thought, no pressure.

Doug has a procedure for adding schematics to his library. He has two Teisco schematics in the miscellaneous section. Not really enough to warrant a Teisco folder yet. May 3 files is the magic number. 

[PRR]

Yes, file your schematic. I like these amps.

The OT is a replacement, and has 300V DC on exposed terminal where a drunk or confused player just *might* get his hand.

As it appears to be a small Champ, a Champ or Valve Jr OT might be suitable.

[smackoj]

I am pretty sure I have a Champ style OT lying around? This amp uses a 7189 output tube which I am not familiar with. I have seen them in old amps but never owned one. The one it came with tested high on my tube tester so that is a good thing.   

[TIMBO]

NICE 

[smackoj]

I wanted to post the schematic and found out that the same schematic was used by both the CM-10 and the CM-17. I don't know why they used the same schemo for the two models? Anyway, here is the schemo for both the ten and the eighteen.

[PRR]

> a 7189 output tube which I am not familiar with.

EL84/6BQ5 sold with a higher plate voltage rating.

Recent-made EL84 will work, so no long-term worries about availability.

The reverb tank appears to be piezo. Hope it never fails. A change to a standard coil-wound tank will need buffer before and after.

> why they used the same schemo for the two models?

Go to the car dealer. About half the models are "the same" as the other half (engine guts, brakes, springs) with different body-bulges and upholstery. I dunno these two amps, but I would assume different box and speaker and chrome. Budget and Extra. In the Japanese market, a 5 Watt amp may have been ample even for "medium size" venues (less need for a 2x6V6 15W DeLuxe).

[BetterOffShred]

Very Cool Amp!  I love the look, and the logo is just killer!  Do you have any sounds clips of it you'd care to share (or make then share) ?    What a great find!
-Brett

[PRR]

> CM-10 and the CM-18 ... same schemo for the two models?

http://el34world.com/charts/Schematics/files/_Miscellaneous/teisco_checkmate_18.pdf

18 has TWO output bottles. We looking at 15W-20W instead of 5W-5W.

18 has double-spring reverb with a kill switch jack.

18 has an added tone pot.

18 has trem injection at push-pull grids; 10 has lamer injection at driver cathode. 10 has no trem-kill switch jack.

18 has an AC outlet (hey, a feature is a feature). And a fuse!

That's what _I_ am seeing. It IS very possible the same "model name" got stuck on various designs. Like 1962 Chevy II/Nova (a basic small car), the 1979 Chevy Nova (a shortened large-car), and the 1985 "Nova" (a Toyota Corolla with a bowtie).

[smackoj]

Sorry gents, my bad. My earlier post SHOULD have said the CM-10 and the CM-17 schemos are the same. Not the CM-18. I somehow got the idea I had the 18 model but it is the 17. I have made the correction on the earlier post and added a "dark" picture of the CM-17 schemo. I couldn't find the option to lighten the picture with my editing program.

Re: sound clips. I will have to wait a short while so I can do a thorough inspection. I did switch it on while hooked to a current limiter and it sounded pretty darn quiet for such an old amp. I did not play a guitar through it yet. Didn't want to leave it on very long before an internal inspection. I may find replaced caps when I pull the chassis?

[PRR]

CM-17

Agree this _IS_ the "Teisco-10" drawing, with one model name stamped-out and another stamped on.

There's probably blueprints at Chevy where "Corolla" is blacked-out for "Nova".

Also note the different names may have gone to different stores. Say Fred's Music had the Low Price on the Teisco-10. Then Gary's Music made a real sweet deal for an essentially-same product. The crates for Gary might say Checkmate 17 instead of Teisco 10. Not the same product, so Fred can't complain when Gary sells a different (he-he) model at a lower price. See also the Kay/Kent/etc family of amps.

[smackoj]

Update on the Ebarn Teisco CM-17;  Pulled the chassis and took a look around. Someone with tech skills has already done a thorough update to the filter caps and most of the other caps. I put it back together and the amp sounds real nice with the vintage 10" spkr. The Tremelo sounds vintage cool but the 'Reverb' pot does nothing. I know PRR mentioned the additional parts needed to convert to spring pan. Any suggestions for this type of reverb trouble shooting? I tested the 12ax7 the reverb uses and it tests good.  thanks

[PRR]

> 'Reverb' pot does nothing.

Even when you spank the pan?

Touch the pan terminals with a meter probe. At least one should give bigger buzz, proving the electronics work.

[smackoj]

Yes sir it has a good loud hum on one of the contact points but slapping the tank does nada.  Should I conclude this tiny tank is bad?

[PRR]

> Should I conclude

I'm deep in a kitchen remodel and too tired to think about this. Ping me next week.

[terminalgs]

Yes sir it has a good loud hum on one of the contact points but slapping the tank does nada.  Should I conclude this tiny tank is bad?

with reverb pot turned all the way down, connect the two cables that go to the spring box together, now turn the reverb pot up.  do you get sound?  If so, then yes, spring box is broke.


since the "wet" signal will be out of phase with the dry signal, ... as you turn up the reverb  the sound coming from the speaker will get quiet and then go near silent (as signals are equal and phase cancels)  then as you continue to turn the reverb up, you'll start getting sound again....