I've made a start :) 50w #102

[martin manning]

Those 120R and 1R 1W resistors will be fine for the attificial CT and current sense resistors.

Half-watt rated resistors will work everywhere except the power supply dropping string (use 2W or3W), the screen resistors (most people use 5W), and the 150k on the FET board (use 2W or 3W).

[norburybrook]

well been slow progress this week as I've been busy in the studio.

Got my preamp board finished today though, here it is;

Couldn't get hold of any of the dale metal film resistors in 110k and 120k, in fact I couldn't get any xircon carbon comp ones either in 110k!!!!!so I've had to parallel a pair of 220k 's . I don't suppose using those CC there instead of MF will make a lot of difference will it?


I have another package arriving from Germany on Monday with the silly little things like countersunk M3 screws, odd resistors, etc. I'd forgotten to order so I can make more progress.



Marcus

[norburybrook]

another day of realising I'd miss ordered parts; 330k instead of 330R....


did a bit of chassis wiring today. Excuse the Chassis it's a left over from another build given to me by a friend. As it came with a nice cabinet as well I was very grateful of the gift which was in exchange for fitting his dishwasher!



Marcus

[lovetone]

Hi Marcus what type of screen cable are you using? looks interesting has a nice screen braid .

Geoff

[norburybrook]

Geoff,

It's this stuff:

http://www.tube-town.net/ttstore/Cables ... :6749.html


They do the white Teflon one as well, but a good friend of mine said for the 102 it's a bit bright and this cheaper stuff sounds better.


Marcus

[norburybrook]

couple of hours today. Things are about to get interesting I think with the switches and relay wiring and all the boards etc on the chassis edges, going to get quite cramped.


Marcus

[martin manning]

You could put that off a bit and build up and test the complete power supplies (HT, bias, and relay), including the power tube socket wiring. Personally I like knowing that all that stuff is working before trying to make sound.

[norburybrook]

that's a good point/idea Martin, however still being in my novice state I'd be a bit unsure as to what exactly I didn't need to have connected to test all that without damaging something


to test the HT/Bias/relays etc then wouldn't I still need to have more or less everything apart from the front panel (tone inputs switches etc) built?



Marcus

[martin manning]

You can assemble the bias/rectifier board, relay supply, and main power supply boards, complete the bias adjust pot wiring, and connect the rectifier output to the main power supply. You can connect the OT, choke, and the plate and screen leads to the power tube sockets. That allows testing of all three power supplies. You can also wire in and test the foot switch jack and the manual OD and boost switches.

No need to have the preamp board or front panel wiring done for this.

[norburybrook]

Doesn't the center lug of the bias pot need connecting to the center of the 2x 220k resistors on the pre amp board by the PI circuit?


Marcus

[martin manning]

Doesn't the center lug of the bias pot need connecting to the center of the 2x 220k resistors on the pre amp board by the PI circuit

Yes, eventually, but you can run the wire from the bias supply to the top of the pot, and the resistor to ground, and measure the bias voltage and range on the center lug.

[norburybrook]

Just checked my 22M resistors for the relay board and they're 1/4 w. will that be OK or do I need 1/2w?

My relays are 5v and 150mW so I'm thinking they'll be OK.


TIA

Marcus

[martin manning]

5V is the coil voltage... nothing to do with the 22M. They are fine at 1/4W, though.

[norburybrook]

Slow progress at the moment what with work and my partner deciding to redecorate !!!

Anyway managed to wire up the heaters and the footswitch/5v transformer for the relays.


It's starting to take shape though.




Marcus

[norburybrook]

Hour or so this evening.

Going to need a steady hand getting the boards wired up.


Any tips here?



Marcus