Noisy Silvertone 1484

[sterve]

I'm trying to track down the source of the static/hiss from this 1484.
After acquisition, I replaced the electrolytics and the hum went away.
I replaced the power cord with a 3-prong. I replaced the jacks with
Switchcraft's.
I thought the OT was shot because of the weak, distorted output.
This turned out to be R34. I have swapped in known good tubes, but still
have a "static with occasional pops" when I come off standby.
I replaced the plate resistors, but did just realize that I used a 1/4W instead
of 1/2W on R34.
The amp has a great sound, except for this sound of frying bacon.
I have yet to replace the can cap with 3 discrete components.
I will finish what I started with these caps and a correctly rated R34, but
any ideas what else if that doesn't quiet 'er down?

[soundmasterg]

Check the nuts that hold the pots on. If they loosen up you'll get random pops and static and you'll have a hard time finding it. This happened to my brother's once. Also replace all the preamp and phase inverter plate resistors as when they go bad this tends to happen along with hiss. Then I'd check the coupling caps in the whole amp for leaking DC. Actually if it was me, I'd just replace them with modern caps like the polyester 225P orange drops. Those brown caps in there were lousy from the start and often leak DC to the next stage. If none of those do it, then I don't have any other suggestions at the moment.

greg

[sterve]

Greg, thanks for the info. I did order some Orange Drops a few days ago
as a just in case. I'll update the thread with the results of the replacements.

[Mike C]

I just fired up a 1484 Silvertone that is more of a white noise generator than a guitar amp. The amp does work only lots of noise in the output regardless of any knob positions. There is no hum though. Would a complete recapping and replacement of the mentioned resistors take care of it. I have no schematic to go by, what are the locations of the resistors. I did find it funny that the original power supply caps ( I think "Planet" was the band name) said on them "one year guarantee", safe to say there out of warranty!

Mike Caldwell
http://www.mikecaldwellaudioproductions.com

[soundmasterg]

I just fired up a 1484 Silvertone that is more of a white noise generator than a guitar amp. The amp does work only lots of noise in the output regardless of any knob positions. There is no hum though. Would a complete recapping and replacement of the mentioned resistors take care of it. I have no schematic to go by, what are the locations of the resistors. I did find it funny that the original power supply caps ( I think "Planet" was the band name) said on them "one year guarantee", safe to say there out of warranty!

Mike Caldwell
http://www.mikecaldwellaudioproductions.com

I'd replace every electrolytic in the amp with modern replacements. you can reduce hum if you replace the ones in the doublers in the power supply with a larger value, as essentially what is in there as stock works out to a 25uf cap. Replace the diodes in the power supply and bias supply with 1N4007's also. They tend to blow. Replace all the rest of the caps in the amp with something modern...Orange Drop 225P's work well, but M150's, Sozos, Xicons, etc would be fine too. Replace all the plate load resistors with modern carbon comps or carbon film or metal film....all the carbon comps in the amp were 20% tolerance types and I'm sure most have drifted. If doing all that work doesn't get rid of the problem, then you've got a head scratcher. I'm not sure what type of noise you're describing anyway?

R34 as noted above is the 100k plate resistor for half of the 6CG7/6FQ7 phase inverter tube. (pin 6) You can get a copy of the schematic from schematic heaven. http://www.schematicheaven.com/barga...ertone1484.pdf There are a couple errors on that schematic but nothing huge. If you're experienced you should be able to spot them.

Greg

[Mike C]

Hello

Thanks for the link. The noise is hiss like interstation FM noise or air leaking. It's loud not in the background. Surprisinginly there is no hum!

Thanks again
Mike Caldwell
http://www.mikecaldwellaudioproductions.com/

[lowbrow]

Have been searching and reading in prep to digging into one of my 1484 heads. Have a question if someone can help me...

...Replace the diodes in the power supply and bias supply with 1N4007's also. They tend to blow.

I'd been looking for replacement diodes and couldn't find any that matched the originals. So then I see the above quote. I'm still new to this stuff and learning a lot, so my question is:

I can see how the 1N4007's sub for the four 1N3194 diodes, but will it also sub for the remaining 1N3754 diode as well?

Thanks! Love reading this forum!

[tboy]

I can see how the 1N4007's sub for the four 1N3194 diodes, but will it also sub for the remaining 1N3754 diode as well?

Yes.