Tube Works Tube Driver TD-752

[ericrudd]

Hi everyone....

I have a TD-752. Works and sounds great. I do have a minor issue now, however. A few months ago, I noticed that the foot switch cable had become frayed, which prevented the channel selector switch from working properly. I cut the problem length of wire off the foot switch, then resoldered the leads to the pair of switches. One is to select channel, the other is to turn on the reverb. Months later, I tried to use the reverb, but it doesn't work. I'm not sure if the problem is related to my soldering job, or if something in the verb actually failed. When I push on the switch, and bang on the reverb...I hear it. When I click the switch, the reverb stops. But no sound from my guitar is getting TO the verb. I have limited electronics background, but I took my mulitmeter and checked continuity from the mother board to the reverb. There are two leads that run to and from the verb. All four runs seem good.

It looks like the reverb on/off is running on the tip of the foot switch TRS, while the channel selector runs on the ring and sleeve?

Is there anything else I can test to get my reverb running again? I don't want to electrocute myself either! I've tried to upload a photo of my foot switch wiring, but the forum upload doesn't seem to work for me.

Best, Eric

[g1]

If you can make the reverb 'crash' turn off and on with the footswitch, your cable wiring is not the problem.

[ericrudd]

If you can make the reverb 'crash' turn off and on with the footswitch, your cable wiring is not the problem.

Woohoo! Did something right. And makes sense.

I assume that the signal to the reverb is always "on"...you're just turning on the return with the switch. (just guessing here) I just don't know what else to check.

Eric

[ericrudd]

Woohoo! I'm glad I did something right.

Not sure what to test next.

[ericrudd]

I may have actually found my problem when I did my testing earlier. It looks like from this page, than I should be able to test continuity through the unit itself. I tried this earlier, when I tested the wiring. Wasn't sure at the time what results I should expect. But from this article...


https://mesaboogie.zendesk.com/hc/en...b-Tank-is-bad-

...it looks like I should have continuity from positive point of the input RCA jack to the output RCA jack, and the same with the negative (shield). I don't believe I did, when I tried this yesterday. I'll retest this evening and see what I get. Might be a bad tank.

[glebert]

Does this have a separate reverb tank or is it integrated into the chassis? I think my 742 was integrated (got rid of it quite a while ago).

[ericrudd]

Separate tank.

[g1]

...it looks like I should have continuity from positive point of the input RCA jack to the output RCA jack, and the same with the negative (shield). I don't believe I did, when I tried this yesterday. I'll retest this evening and see what I get. Might be a bad tank.

Not continuity between the two jacks. Continuity between hot and ground of the input jack on the tank itself (we know the output end is ok).
Measure resistance across the input jack of the tank (tip to ground) and post your reading.

[ericrudd]

Good morning, Mr. G1.

I measured last night across the input tip and ground (both the ground on the jack itself and the chassis of the tank). I got no reading at all. I did the same across the output (which I did after watching a DIY video on tank testing) and got 198Ω.

Now, I'm assuming I was using my meter correctly. I had it set to 200Ω. I didn't think I wanted to set it to the higher values available....2k, etc.

Thank you for all your help. Sincerely.

[The Dude]

If you got no reading across the tank input, either the transducer is open, or (more likely) there's a broken wire going to the RCA connector. Look inside the tank and you'll see two wires going to the connector on the inside. Make sure one of them is not broken. Sometimes the wires will look soldered, but a slight tug will show a break.

[g1]

Agree with The Dude. You have likely verified that the tank is bad, and it may be repairable if it is a broken wire inside.
However, if you were on the 200 ohm range, on the off chance it measures a little over 200, try the 2K range on your meter.

[glebert]

If you got no reading across the tank input, either the transducer is open, or (more likely) there's a broken wire going to the RCA connector. Look inside the tank and you'll see two wires going to the connector on the inside. Make sure one of them is not broken. Sometimes the wires will look soldered, but a slight tug will show a break.

I have also had tanks that would measure OK in one orientation and then open up when rotated. I will usually reflow the solder if there is any chance it is a bad joint.