TheMadKing
New Member
Yes, see the transistor discussion above in this thread. If you replace transistors, be mindful that the transistor leads must be installed in the same configuration as the original board. Refer to the service manual and the circuit board. Test any transistors and realign them (emitter/collector/base) if the order is not the same as the schematic requires. (You can use short pieces of wire insulation to insulate the transistor leads that may need to be crossed.) Also make sure the transistor specs are equal to or very close to the service manual specifications.
I found this problem very frustrating to resolve - I ended up replacing the servo board with a used one which solved the problem immediately. I have the old board and can repair it to use as a spare if needed down the road.
Finally, poor connections at the plastic molex connection to the servo board can cause strange speed issues. It is molded onto the wire leads of the capstan motor assembly, which doesn't facilitate an easy swap of the connector. If you are careful, you can cut off the molex connector and connect the wires to the servo motor prongs with crimp connectors. Make sure you get the correct wires onto the correct prongs. Crimp them down tightly and gently weave some insulating tape between the finished prongs to prevent shorts down the road. Not the most elegant solution but it works, especially since the molex connector is nearly impossible to find.
I'm not a big fan of total recaps - however, I have done it in the past, and mostly regretted the time it took and wear and tear on old circuit boards. That being said, I found nearly all of my RT-701 caps were no longer near original specification. So in this case, it was a good thing, but use your best judgement. The preferred approach is - fix only what you know needs fixing.
I found this problem very frustrating to resolve - I ended up replacing the servo board with a used one which solved the problem immediately. I have the old board and can repair it to use as a spare if needed down the road.
Finally, poor connections at the plastic molex connection to the servo board can cause strange speed issues. It is molded onto the wire leads of the capstan motor assembly, which doesn't facilitate an easy swap of the connector. If you are careful, you can cut off the molex connector and connect the wires to the servo motor prongs with crimp connectors. Make sure you get the correct wires onto the correct prongs. Crimp them down tightly and gently weave some insulating tape between the finished prongs to prevent shorts down the road. Not the most elegant solution but it works, especially since the molex connector is nearly impossible to find.
I'm not a big fan of total recaps - however, I have done it in the past, and mostly regretted the time it took and wear and tear on old circuit boards. That being said, I found nearly all of my RT-701 caps were no longer near original specification. So in this case, it was a good thing, but use your best judgement. The preferred approach is - fix only what you know needs fixing.
