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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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19th Sep 2020, 1:37 pm | #1 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
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Bandmaster Powerhouse Tape Rythm Machine
Bmi Powerhouse - tape rythm machine - 8 track stereo cassette.
It's been got at. The track has been cut around the motor control circuit, a voltage reduction transistor and Zenner on a bit of strip board has been added to reduce the voltage to the motor, and modify the range of the tempo control. The two pre-sets are marked 220 ohms each, one reads 1.2k and the other reads 3.5k. I removed the mod, repaired the track, fitted new pre-sets and the tempo control now varies the motor speed over a wide range. The motor connections are white and pink in a screen. The screen has come off the pcb due to very bad soldering and is floating free. The screen is not connected to the case of the motor, if I connect the screen to earth, then the motor runns at full speed and the tempo control has no effect. I need to know where on the pcb the screen should be soldered. Someone has made a right bodge of this but I am getting it back together. If anyone has an official copy of the cct diag I could do with a copy, I have drawn out the cct on paper and it seems to make sense so far. John. |
19th Sep 2020, 6:24 pm | #2 |
Heptode
Join Date: Jan 2009
Location: West Lothian, UK.
Posts: 761
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Re: Bandmaster Powerhouse Tape Rythm Machine
I know zilch about the machine - but if the screen is not connected at either end but you get a problem when you connect it to something - then I would check that there is not a short from screen to one of the inner wires.
Especially if bad soldering may have melted some insulation?
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George |