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Old 22nd Sep 2019, 9:33 pm   #1
Goodizzy
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Default Rogers Ravensbourne amp restore

Good afternoon,

I have acquired a "working" Rogers Ravensbourne amp after being bit by the collector's bug. I have a few other amps from the era and love these early transistor designs!

Before plugging it up to the variac, I've been cleaning it with a dry brush and blowing the dust out with compressed air. (It was dirty!) The amp appears to be all original. (to my eyes at least)

I have a few questions I'm hoping you guys could answer-

- The amp didn't come with a wooden case. I've taken off the metal brackets on both sides of the amp's chassis, exposing the input PCB and the mains transformer sides of the amp. Is there a method to get to the bottom of the amp to complete my brushing/blowing? (There are a lot of screws on the underside)

- Is it safe to clean the topside of the amp's PCBs with denatured alcohol or equivalent cleaner? How about the face plate?

- The speaker connectors are funny in this amp and didn't come with my purchase. I have a few spare of the Rogers/Armstrong 2-pin connectors from amps like the Armstrong 500 series. I haven't gotten them out to see if they would be direct replacements since I haven't figured out how to access the underside yet.

- Would it be advantageous to spray the push buttons with switch cleaner or deoxit? I haven't seen these types before so I don't wish to damage them.

- Any other general advice or known issues I should address before firing the amp up? I imagine it may need a recapping and bias adjust once I can get it running.

I appreciate any help you guys could provide. This place is a wealth of knowledge for someone like me far away and I always enjoy conversing about this equipment. Regards,

Chris
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Old 22nd Sep 2019, 10:00 pm   #2
ajgriff
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Default Re: Rogers Ravensbourne amp restore

The manual can be downloaded from Hi-Fi Engine once you've completed the simple free registration process. You will find some guidance regarding the chassis only version plus other useful information.

- Denatured alcohol should be fine for internal cleaning but be careful with the legends on the front panel.

- The speaker outputs are standard (then) two pin DIN sockets like the Armstrong.

- Cleaning the switches as you describe would be well worthwhile.

- Check for obvious signs of component deterioration before gently bringing to life with the Variac (monitor current of course).

Hope this helps. I have a Ravensbourne on the to do pile so haven't yet gained direct experience!

Alan
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Old 22nd Sep 2019, 10:29 pm   #3
Trevor
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Default Re: Rogers Ravensbourne amp restore

Congratulations you have obtained a design classic very underated I first met with these nearly 50 years ago a design classic very valve like in its sound
Most unusual in design
I still have a no of these
Trev
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Old 22nd Sep 2019, 11:51 pm   #4
RojDW48
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Default Re: Rogers Ravensbourne amp restore

I had one of these for a long time. A very good amp. I recall the push button equalisation for TT input, while very clever, was susceptible to 'splatting' (dirt, shaky contacts etc) - give it a good clean and squirt of Servisol.
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Old 23rd Sep 2019, 9:35 pm   #5
Trevor
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Default Re: Rogers Ravensbourne amp restore

If you use the search function and type in Ravensboune you will find a few good threads on your amplifier
Trev
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Old 4th Jan 2020, 6:35 pm   #6
Goodizzy
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Default Re: Rogers Ravensbourne amp restore

I have torn the amp down to all the individual boards and given it a thorough clean. It was extremely dusty, having been stored without a case for years. I also fully recapped all the amp boards with the exception of the two power supply caps, C40 and C41, which I have on order. (3900uf 50V)

I washed the chassis with a bit of soap and water as it was very greasy and full of fitlth. Upon further examination I am wondering if I am missing parts here? There appears to be a single threaded gold bushing on the Balance control. Should they be on all four pot thru holes? There also was only one spring for any of the four pot shafts. Should all shafts have springs? I have attached a picture of the chassis for ease.
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Old 4th Jan 2020, 6:53 pm   #7
julie_m
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Default Re: Rogers Ravensbourne amp restore

The balance control probably is a mono pot, set backwards on the board so the spindle passes through that extra bush. The volume, treble and bass controls will be stereo, and their threaded bushes will poke directly through the panel.

I'd have tried to line up the balance control with the fronts of the others if I was doing it, but Rogers probably had a good reason for doing it that way.
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Old 4th Jan 2020, 7:13 pm   #8
Goodizzy
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Default Re: Rogers Ravensbourne amp restore

Thank you- most helpful!
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Old 5th Jan 2020, 10:48 am   #9
snowman_al
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Default Re: Rogers Ravensbourne amp restore

Quote:
Originally Posted by Goodizzy View Post
... Upon further examination I am wondering if I am missing parts here? There appears to be a single threaded gold bushing on the Balance control. Should they be on all four pot thru holes? There also was only one spring for any of the four pot shafts. Should all shafts have springs? I have attached a picture of the chassis for ease.
My guess is there is only that one bush. It is simply a locator for the front panel. The other will be the normal volume control bush once re-fitted.
Aren't the controls mounted on another bracket behind the chassis any way?

Not sure what 'springs' you refer to?
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