Bandmaster Powerhouse Tape Rythm Machine - UK Vintage Radio Repair and Restoration Discussion Forum

theredhouseinn · 19th Sep 2020, 1:37 pm

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.

buggies · 19th Sep 2020, 6:24 pm

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?

19th Sep 2020, 1:37 pm	#1
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	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
buggies Heptode Join Date: Jan 2009 Location: West Lothian, UK. Posts: 761	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? __________________ George