09-13-2009, 05:05 PM
On to the Chassis:
Very crowded. Lots of nodes with three or more connections. Many hard to reach parts. Lots of plastic coated wires to replace.
One very nice thing about this radio is the wiring diagram that's included with the schematic. I decided to start on the audio output since it was the most clustered. Spent a few hours going over all of the nodes so I could select a sequence to minimize the number of parts that were desoldered at any one time. For me I found it best to replace all of the capacitors, resistor and wires at a node without removing the old parts from the other end so there was less chance of connecting the new part to the wrong node. I also spent some time looking at the wiring diagram to find the location on the schematic to help verify that I'm using the correct replacement part.
All of the capacitors and any of the resistors off spec more than 10% were replaced. I'm not sure if that was necessary or not.
I left the three electrolytic cans on the chassis so I could use them to support the chassis while I was working underneath.
One thing I didn't care for with the design is chassis ground. Rather than attaching a terminal strip a tab was punched out to make the connection. Lots of heat and flux needed. That may not have bee a problem for the people making the radio but it is for me. I like my new parts untoasted. To get around that problem most of my ground connections were made to a quarter inch of the old capacitor or resistor lead that I would leave attached.
Heat shrink was pushed over the transformer wires. I'm ready to connect a new power cord soon but there's the cap pack with three capacitors and three resistors that are embedded in back plastic, which is housed in a metal box on top of the chassis. It will be a huge mess to melt and recover the box. For me, I'd rather just connect the components in a tight bunch and run the four wires as necessary to the pots. I'm not sure why the six parts were bundled in such a well build metal box. Is it shielding? If not I'd prefer to leave it hanging inside the chassis near the on-off switch.
Interesting comments about the Fluke meter. Mine is a hand-me-down that's probably 20 years old but the thing still works. Never had any problems other than to annoyance of selecting a new range all of the time.
Very crowded. Lots of nodes with three or more connections. Many hard to reach parts. Lots of plastic coated wires to replace.
One very nice thing about this radio is the wiring diagram that's included with the schematic. I decided to start on the audio output since it was the most clustered. Spent a few hours going over all of the nodes so I could select a sequence to minimize the number of parts that were desoldered at any one time. For me I found it best to replace all of the capacitors, resistor and wires at a node without removing the old parts from the other end so there was less chance of connecting the new part to the wrong node. I also spent some time looking at the wiring diagram to find the location on the schematic to help verify that I'm using the correct replacement part.
All of the capacitors and any of the resistors off spec more than 10% were replaced. I'm not sure if that was necessary or not.
I left the three electrolytic cans on the chassis so I could use them to support the chassis while I was working underneath.
One thing I didn't care for with the design is chassis ground. Rather than attaching a terminal strip a tab was punched out to make the connection. Lots of heat and flux needed. That may not have bee a problem for the people making the radio but it is for me. I like my new parts untoasted. To get around that problem most of my ground connections were made to a quarter inch of the old capacitor or resistor lead that I would leave attached.
Heat shrink was pushed over the transformer wires. I'm ready to connect a new power cord soon but there's the cap pack with three capacitors and three resistors that are embedded in back plastic, which is housed in a metal box on top of the chassis. It will be a huge mess to melt and recover the box. For me, I'd rather just connect the components in a tight bunch and run the four wires as necessary to the pots. I'm not sure why the six parts were bundled in such a well build metal box. Is it shielding? If not I'd prefer to leave it hanging inside the chassis near the on-off switch.
Interesting comments about the Fluke meter. Mine is a hand-me-down that's probably 20 years old but the thing still works. Never had any problems other than to annoyance of selecting a new range all of the time.
