Bandmaster Reverb vibrato

[jc_giggs]

I found a 74 bandmaster reverb that didn't had the vibrato roach cut out. I scored two "roaches" from a friend but I have found that the vibrato works until I turn the speed down to about 4 and then it stops. it also stops when I run the speed at 10. It works and adjusts fine on settings from 5-8. Also, when I turn up the intensity, then overall volume goes down. I have tried both roaches and have gotten the same results with both. Thanks

[mac1amps]

When those vibrato (actually they're technically tremolo, not vibrato) networks die out at slower speeds it usually means the cathode by-pass cap is bad in the oscillator ckt. Dies out at the higher speed settings? Boy, in all my thousands of Fenders I've serviced over the years, I don't recall running into that scenario. In theory it COULD be something with the "speed" pot, but in the real world I really doubt if that's the problem.
With respect to the volume drop at higher "intensity" settings, that usually means that the photocell inside the neon/photocell module ("roach" as you call it) is at fault.

[52 Bill]

...the vibrato works until I turn the speed down to about 4 and then it stops. it also stops when I run the speed at 10.

As mac noted, check the pot and the bypass cap, but also check the tube.

Also, when I turn up the intensity, then overall volume goes down. I have tried both roaches and have gotten the same results with both.

If this happens when the vibrato is turned off, the photo cell is bad and needs to be replaced. If you mean it happens when the vibrato is running, this is normal as this is part of the effect.

[jc_giggs]

The volume decreases when the trem circuit is activated and volume is further decreased as the intensity is turned up. There is no decrease when them trem circuit is not activated.

[jc_giggs]

the volume is decreased by the intensity only when the trem circuit is on

[jc_giggs]

Tell me more about the diode by-pass cap and its location. How can I test to see if it is functioning properly?

[52 Bill]

Tell me more about the diode by-pass cap and its location. How can I test to see if it is functioning properly?

Get yourself a schematic for your amp. Even if you don't understand it, it will make communications here easier.

If you look into the end of the roach with the vibrato pedal turned on, can you see the neon light bulb light up? Look from the back side of the amp chassis.

Does the light flash on and off? Does it change flashing speed when you rotate the speed control?

[jc_giggs]

I have checked the neon buld and yes it is working properly by lighting up when the foot switch is clicked and the led also pulsates at varying speeds. I do have a schematic and a chassis layout. I am able to slightly understand the chassis layout but not the schematic. The prints that I have are for a AA1069. I however am uncertain if this is what my amp is. The faceplate says TFL5005D. On the back, beside the UL listing it reads: Fender Musical Instruments; Fellerton California. it also has a stamped number on the far right beside the reverb input that is A 45076. Do I have the correct schematics?