marcas58 11/29/2013 11:18 AM
randall rb60 schematic
Hi, im looking for randall rb60 schematic
any help will be appreciated,, best regards..
 
Jazz P Bass 11/29/2013 1:55 PM
Randall RB60 Schematics
 
DrGonz78 11/29/2013 3:48 PM
Jazz, I don't think those are the right schematics. Is this an old Randall RB60 or a newer one? These schematics are very hard to find and I always keep an eye out.
 
marcas58 11/30/2013 6:06 AM
randall rb60
Quote Originally Posted by DrGonz78 View Post
Jazz, I don't think those are the right schematics. Is this an old Randall RB60 or a newer one? These schematics are very hard to find and I always keep an eye out.
is an old randall rb60
is a solid state amp combo.
 
DrGonz78 11/30/2013 6:09 PM
Yeah it's really hard dealing with Randall directly trying to get the service schematics on older amps. I also see schematics for this amp around the net for sale. Buyer beware if they are really selling a owner's manual that includes the block diagram. Perhaps they will list the item saying schematic included, but then state not a service manual. Still it might acually be the schematic, but beware. If you go with the schematic connection site I would email them to verify what they mean by the "Schematic" and not block diagram. Good luck!

"http://www.schematicconnection.com/store/asp/product.asp?recorprod=1&product=337&cat=153&ph=&keywords =&recor=&SearchFor=&PT_ID="
Also, out of curiosity what's wrong with the amp? Or you might just be wanting to mod the amp and need the schema.

BTW if you call Randall to ask for the RB60 and they don't have that then also ask for the RG60, perhaps they have that one.
 
dmeek 11/30/2013 7:03 PM
I have this very low quality schematic. Maybe will help.

Doug


http://music-electronics-forum.com/a...1&d=1385863311
 
marcas58 12/2/2013 6:29 AM
randall rb60
Quote Originally Posted by dmeek View Post
I have this very low quality schematic. Maybe will help.

Doug


http://music-electronics-forum.com/a...1&d=1385863311
Thanks, this is not what i looking for i already have this one this is a guitar amp the one i am looking is a bass amp
it has a little board in top of the main board with one IC dual op amp the problem of this amp is that it has no bass at all
the bass control works i have canged some capasitors related with the bass and still not enought bass it s
ound like a guitar amp with the treble very high.
 
badjackson 10/9/2017 12:43 PM
Thanks for the schematic dmeek, but the resolution is too low for me to read. Does anybody else have a higher resolution schematic that they wouldn't mind sharing?
Thanks!
 
J M Fahey 10/9/2017 7:32 PM
What is the actual problem you are trying to solve?
I used to have that schematic, ages ago, on a crashed computer; if I happen to find it IŽll post it.

In any case, the G60 and B 60 are *exactly* the same amp, just the Bass one has no reverb so donŽt search for a specific B60 schematic because it never ever existed.
 
badjackson 10/10/2017 6:30 AM
JM, thanks for letting me know that the G60 is the same circuit...i'll look for that schematic.

I just wanted to see the topology of the power amp stage. I think I can fix this RB60 without the schematic, but it would help to have one. One side of the power amp blew and it burned up a 100 ohm 1/2W resistor in the process, so I'm replacing the resistor and most of the silicon devices on that side and both the output transistors. It would be nice to know where the 100 ohm resistor is in the circuit and how it ties in with the power stage.
 
J M Fahey 10/10/2017 7:40 AM
Still without my computers, all died from tablet to desktop to notebook, but just as a suggestion, designers in general tend to have some pet ideas (good or bad) and tend to repeat them all over the place, the point being it should be very muchalike others same era.
IŽll blow the fuzzy one up, not to read values (impossible) but to compare it side by side with the widely known RG100 power amp. (hint hint)

RG100 uses constant current output but besides that everything else should be quite close.
100 ohm resistors in such a vintage amp are usual connected Base to Emitter at the power transistors and often die in flames accompanying dead power (and driver) transistors, so check them in any case.
 
Jazz P Bass 10/10/2017 10:09 AM
Here is the RG 80-100 power amp schematic.

The 100 ohm resistors on shown on the driver transistors.

[ATTACH]45256[/ATTACH]
 
badjackson 10/12/2017 6:56 AM
Thank you very much for the schematic Jazz P Bass! Also thanks JM for sharing your experience and suggestions. I'll get this thing working as soon as the new parts arrive.