If your circuit has a bias balancing scheme and the fixed/cathode Biasing achieved with this e150 ohm resistors, then you have an AB568 amp…and it did not come with a BF panel. Those 150ohm resistors were introduced in the May, 1968 circuit…AB568…along with the 2000pfd snubber caps. #Bandmaster reverb tfl5005d proThat was introduced first in January, 1965 in the AA/AB165 Bassman and the AA165 Pro Reverb. Neither one of these circuits has a bias balancing scheme….if that is what you are describing. Since an AA864 predates the AA964….AA864 being drawn in August, 1964 and the AA964 being drawn the next month…September, 1964. However, such an amp is not a combination of any of those features except the GZ34. The Schematic for an ‘AA864’ Vibrolux Reverb is not readily available, it seems. On the JJ tubes there's a low blue light on the base of both tubes and it's flashing while the signal is become stronger.ĭoes the glow on the GE tube implies a bad tube? I noticed that the General Electric tube have a permanent blue glow inside that is become stronger as the signal gets stronger. Last thing, I have two pairs of 6L6GC tube, an old one of RCA and General Electric and a new JJ tubes. In this video you can see the problem with the tremolo engaged: Or there's another thing I can do to solve this problem? Increasing the 220K resistor that connecting the plate of the oscillator tube to the B+ can help to control over the tremolo? When the volume is at 8 the amp brakes, when the tremolo tuned off there's no problems at the same volume. The same kind of distortion is happens when the tremolo is on. In this video you can see the problem coming from the reverb tank: #Bandmaster reverb tfl5005d driver*I tried to replace the reverb driver with the phase inverter and the reverb recovery tube with another 12AX7 with no change, so I don't think the problem is in the reverb driver or the recovery tubes. So the reading of the input transducer seems to be a little bit lower.īefore ordering a new AB tank there's any think worth to be checked? This page says that the 64063 4U1 DC resistance should be :64063 (I:1.1 O: 172) The DC resistance I measured is 0.9R at the input and 171R at the output. The original tank is Gibbs marked 64063 4U1. I don't sure if the higher input impedance of the BB tank is making this improvement or it's a faulty AB tank. I don't have here another 4AB type of reverb tank but with a type 9BB the amp doesn't make any problems. When the reverb is disconnected from the amp the amp doesn't breaks that way even on volume of above 8. When the reverb tank is connected the amp brakes on volume of 4. Hi, I have here an AA864 Vibrolux Reverb amp which I re capped and re tubed.
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