Question: to repair orig. reverb or replace it with a different design?

[smackoj]

Hello again amigos; I posted this Teisco Checkmate 17 (made in Japan) amp when I first got it a month ago. I have since been trying to get the reverb to operate with no success. According to PRR this little spring pan is run by piezos. I did check and there is power to the 'send' connection on the pan but I get no modulation at any setting (It has one knob for the reverb setting). This Teisco reverb is run by both halves of a 12AX7 as seen in the schemo. I have several high quality 6mb8 tubes in my stash and a couple small 3 spring pans, so I have the parts (provided the pans are a match?) to switch it over to a "Tubenit" one tube design but I'm not sure if that is the best way to get the reverb running?

I would like to hear from any in this group how they would proceed to get this verb running? Switch it or fix it?
 
gracias amigos
 

[sluckey]

This Teisco reverb is run by both halves of a 12AX7 as seen in the schemo.

No, only one half is used for reverb. The other half does the tremolo. Are you willing to sacrifice the tremolo to build the one tube reverb?

It's doubtful you will find a replacement for that reverb tank, so just how much are you willing to modify this amp to have reverb and tremolo?

Here's an idea if you want both and don't mind a little extra work. I probably would not do this unless I was really bored or sufficiently challenged to prove I could do it. 

OK, pull the 6X4 and use two 1n4007s for the rectifier. Put a 6AV6 in that empty socket and wire up the tremolo circuit (you don't have to rewire the filament pins). Now rewire V2 socket for the 6BM8 reverb circuit. I suggest treating this as three totally separate mods. I would do the ss rectifier first and check that everything still works. Then do the tremolo second and check that everything works. Finally do the reverb circuit.

[smackoj]

Thx SL; I like the tremolo as it is now, stock from factory. I don't want to mess with that. I toyed with the idea of building a small pcb add-on for a SS reverb circuit but I don't have the proper voltage in the amp without adding another transformer which I am hesitant to do, not much room in there. I suppose I could run it with a wall wart but I'm no fan of that idea. So I think for the time being I'll leave it alone. It sounds very good and the trem has a good sound.

thanks for your assistance.   

[PRR]

I got tried-up.

Here is what I wuz thinking. I may not be thinking clearly.

The 6BM8 transformerless demands nearly as much current (B+ and heater) as your output bottle. On a single small power-bottle amp, that may be a lot of added load.

I really believe in tube & transformer reverb drive.

Can you afford, and fit, the small reverb transformer used with 12AT7 reverb (most Fender onboard reverb)?

The wound-spring tank is less efficient than the piezo. We will need another gain stage.

I really don't want to add another tube. An op-amp chip will work; so will a JFET (I think). Added complication of a low-V supply. Of the two, I favor the JFET as more in the spirit of the all-SE amp. But an op-amp is more sure of enough gain.

This won't be Pismo Beach surf reverb (the 12AX7 isn't up to that), but ample for many musics.

[smackoj]

that looks doable PRR, thx. I'll have to get a Rev. transformer first. I don't keep any of those around. I do however, have plenty of Jfets on hand and in most applications I've done the J201 has a very good amount of gain.

thanks again.  Jack