FDP Forum / Bandmaster reverb with master volume/ 6 messages in thread.

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Terryrocks



Usa

Jun 29th, 2016 03:27 PM        

Plugged in a guitar, sounds ok. No buzz or extraneous noise. <br /> However, reverb and tremelo do not work. I assume it's tubes, but the master volume pot looked like an aftermarket mod and potential source of the problem until i opened her up. <br /> The wiring looks factory.<br /> I think the tubes might even be original.<br /> <br /> Here's some pics of the xformers, chassis wiring and power tube pins.<br /> <br /> https://flic.kr/s/aHskCr7eBe<br /> <br /> <br /> Once I get the reverb and tremelo back online, what would any of you recommend I do to improve the tone of this amp?<br /> I also own a 69 dripedge bandmaster reverb with awesome tone, so I have a control of sorts.



BbendFender

Contributing Member
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American Patriot

I'm on guard these days.
Jun 29th, 2016 08:58 PM        

You might experiment (check) your preamp tubes. If you have a way to test the tubes, see if all tubes are functioning as they should. Check your bias also.<br /> <br /> By the way, what was wrong with the reverb and tremolo? How did you get them working?



Terryrocks



Usa

Jun 30th, 2016 08:58 AM        

I haven't gotten them back working yet, but I do have a 69 dripedge version of the same amp, so I can just borrow it's tubes for reverb and tremelo to see if the circuits are functioning.



Hammond101

Contributing Member
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So. Cal. USA

Jun 30th, 2016 09:44 AM        

Nice clean chassis, looks to be a '75 model.<br /> <br /> I'd make sure the filter and bias caps are fresh. Your chassis pic shows an original bias cap in the amp. If the filters are original replacing them will tighten it up quite a bit.<br /> <br /> The most common mod for this amp is to put a Bassman output transformer in it and blackface the power section. The stock tranny is a bit soft to some people and makes the amp sound a bit saggy IMO.<br /> <br /> I'd also change it from bias balance to bias adjust or add bias adjust. Grid/plate resistors may be out of spec in the preamp so they and the slope resistors should at least be checked. The condition of the bypass caps should be checked too.



Steve Dallman

Contributing Member
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Merrill, Wisconsin

Age is just a number...mine is big
Jul 2nd, 2016 08:12 AM        

You know the footswitch has to be used to make the vibrato work? If nothing is shorting the vibrato pedal jack, it won't work.<br /> <br /> The most common problems with the reverb are inside the tank. Wires break off, springs let loose. Take the reverb tank out and inspect the insides and check the resistance of the input and output. Check the cables. Plug all back in and continue testing. <br /> <br /> While I have found the output transformers of blackface Bandmasters to be easily saturated, that was back in the days of no PA support and high stage volume. I have not found silverface Bandmasters lacking the headroom blackface models did. Today, I'd not be so quick to put in a larger transformer. (In the 60's and 70's I would not have considered gigging with a Deluxe Reverb or a Princeton Reverb. Today, either would be fine for me.)



Roly

Contributing Member
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Whitehorse Canada

I don't get out much
Jul 2nd, 2016 03:42 PM        

The DC resistance of the reverb input should be roughly 1 ohm, output DCR should be roughly 180 ohms. Any readings close will be fine.<br /> <br /> If you don't get similar readings, either the tank is buggered or your reverb cables have failed.



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