Princeton clone build: blowing fuses

[timrobertson100]

Missed your response ToneMerc. Thanks also.
Yes it was (supposedly) all wired according to the first diagram. I've spent a long time on it today, tracing and buzzing things through. I found a short between one heater and ground on the lamp, so with luck that and maybe a surge on power up is it.

[Firestorm]

Princetons have a 1A slo-blo on domestic and export models. The Rivera Princeton II has 1.5A on the exports. Wouldn't it be great if the whole problem is the wrong fuse?!

[timrobertson100]

Thanks guys. Would be lovely yeah... When the light was on the few times, and the 2 times it powered up with the rectifier tube though it hissed and then blew - now maybe that was the hairline short on the lamp.

When I get the new fuses I'd run through this procedure:

a) power up with no secondaries connected - check secondary voltages
b) connect lamp only, check it lights up
c) add the heater wires, check heater voltages
d) add the big cap and diode assembly (no rectifier)
e) add the rectifier

If that doesn't look right, please can someone shout at me in advance?

Cheers.
Tim

[Firestorm]

The rectifier will not notice anything going on with the 6.3VAC winding. Be very sure the high voltage stuff is wired right.

[Tillydog]

I feel kind of ridiculous having blown 13 fuses today...

Dude, build a 'light bulb limiter' (See the sticky at the top of the page). You wouldn't have blown any fuses, or be playing 'Russian Roulette' with your power transformer.

[timrobertson100]

Well I got my hands on a 2 amp fuse today from the car garage, and figured what the heck. Went through steps above and everything is fine - the hissing sound I first heard was the rectifier tube (presumably burning off some chemical or something?) but it stopped after 5-6 seconds, and subsequent power ons don't do it. Currently I have a few 100 volts DC on the B+, so time to stick some signal tubes in methinks...

[timrobertson100]

w00t. She works!

10 hours p%%sing around and it sounds like there is just a surge current flowing too much on startup...

I'll swap that out and stick an 1A in when I can get one.

Thanks guys for all the info. Would have been lost without you... seriously.

[ToneMerc]

Good deal, enjoy

TM

[timrobertson100]

Only the reverb doesn't work (pulling out the send cable from the amp and touching it comes through varying in volume on the pot, so I assume something is wrong in the signal path out to the can).

[timrobertson100]

I feel stupid #2:

That foam in the middle of the reverb can? That's just for safe packaging when shipping and not actually part of the fender mojo. D'oh. All good when you take that out.

I understand why everyone loves these amps. I din't get this immediate attachment to the 5f1 I built (why don't they put on the circuit that the 5f1 only sounds good at full volume), but this princeton sounds super lush even at apartment levels.

Just for those who stumble on this:
I put my last one and only 0.5A fuse in and she blew on start up. Seems this amp pulls too much current on startup. I am using a 2A fuse now, but fully intend to try a 1A as soon as I can get one.

A sincere thanks to all for pitching in and helping. See you shortly on the 5f6a thread I'll start in a couple weeks when that one doesn't work too

[ToneMerc]

See you shortly on the 5f6a thread I'll start in a couple weeks when that one doesn't work too

Cool, I just got my chassis parts in for a quad 6V6 version that I will be doing next.

TM