Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Lon on February 05, 2016, 02:18:36 pm
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Hello Forum!
Great to find this place! I am far away from home and need to fix my 60 tremolux - Fender Tremolux-6G9-B- rectifier GZ34
What are the max filter cap values that I can put into this amp. I put in 47ufs (500 volt- because I m told that the line voltage here is a little higher than the states.
I read in this forum that the rectifier tube a champ can only handle up to 33uf in the"first position" filter cap. This got me worried. I'm am not sure which is the first position - I think its the one on the end that has the resisters
thanks for your help
Lon
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47 is fine for the "first position" with a GZ34 - That is the first electrolytic cap connected after the rectifier output.
Second position would be the next Electrolytic stage after the choke or power resistor(you should have a choke)
Technically after that "first position" you can pile on the capacitance, but most seem to stick with values at or around stock.
Just use caps that are rated enough voltage-wise
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The original amp used 16µF caps. There should be five under the 'doghouse' cover. Did you replace all five caps with 47µF caps?
I'm asking because the first two caps are connected parallel so they are equivalent to a single 32µF cap. If you replaced those with two 47s, then you have a total of 94µF for your first cap. That's probably dangerous for your GZ34! If this is the case, just remove one of those caps.
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By the way- I think my choke is bad. I saw one with the same part number as on the schematic at Doug Hoffman's web site for tube amps. Any one ever used his parts? The site looks fantastic!
thanks again!
Lon
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Thanks for the help. I'm going to try to attach a jpg that is smaller than 800kb so that I can get an idea of which is the first position. (Got the pixel thing right this time on the image. )I will also try to follow the circuit back
to the rectifier. What is a safe way to discharge the filter caps?
Thanks a lot
Lon
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Doug Hoffman (our host here) is an excellent parts supplier and you can't go wrong ordering from him. But why do you think your choke is bad?
Since it appears that all of the caps have been replaced with 47uf caps, you need to do what sluckey suggests in the third post.
EDIT: I'm getting confused looking at various photos and trying to understand the cap wiring, so I will defer to those with more experience/expertise with regard to which of the caps to remove.