Amp ID?

knockbill

knockbill

Lunatic Member
Got this little amp last week, just getting around to checking it out,,, SPOTMASTER BEA-20,,, Bass/On/Off,,, Volume,,, Treble pots on the front,,, Speaker jacks C-4-8-16,,, two RCA jacks,,, line cord on rear panel...
It has 3 tube sockets, only one tube in place, Mullard 6267 + 7pin rectifier, possibly 6X4? and 9pin output tube...
Anyone know this guy,, or the company,,, schematic?
Thanks...

Googled SpotmasterBEA-20 Links to Broadcast Electronics, Inc,,, https://www.americanradiohistory.com/Archive-Catalogs/Broadcast Electronics/Spotmaster-1974-Audio-&-Carts.pdf

6267 tube,,, https://tdsl.duncanamps.com/show.php?des=6267
 

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Thanks,,, seems to be... In looking for a schem for it... seems missing tubes are 6BQ5 and 6X4,,, I found a conversion to guitar amp, which was my intention when I got it!!! we'll see how that goes... In the meantime, it would be nice to try to run it stock and see what we have here...
 
Took the front cover off this thing to release the pots and get the chassis out,,, Its built in a Heath AA 191 box,, which is like brand new... Can't imagine the BEA plate was off in 60 years! I'll give a quick try to see if it works, if I can test the 6267,, but with the condition of the front plate /lettering, I'm not gonna chop or modify it for git amp use... Some one may have a use for it...
 

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radioactive said:
http://www.heathkit-museum.com/hifi/hvmaa-191.shtml
It more than likely was a Heathkit as 191 to begin with.
Click to expand...
Not sure wiring would match 191, I can't find a schematic... Power switch is on the Bass pot,, so no slide switch,,, and there isn't a selector switch on this chassis... Possibly the same otherwise tho... I haven't removed chassis from box,,, I can post a pic when its out...
I brought it up on a variac with a good 6X4, and 6BQ5,,, have to check 6267 yet... Got B+ thru the can cap, but no sound at all...
 
knockbill said:
Not sure wiring would match 191, I can't find a schematic... Power switch is on the Bass pot,, so no slide switch,,, and there isn't a selector switch on this chassis... Possibly the same otherwise tho... I haven't removed chassis from box,,, I can post a pic when its out...
I brought it up on a variac with a good 6X4, and 6BQ5,,, have to check 6267 yet... Got B+ thru the can cap, but no sound at all...
Click to expand...
I've been looking for a schematic for it as well and found someone on diy audio that posted one but I'm not a member there. Thread is here.
https://www.diyaudio.com/forums/tubes-valves/206857-heathkit-aa-191-a.html
You could also search for heathkit ea1 as its the same amplifier as the AA 191 except for the faceplate. Heathkit did this alot. As far as sound goes I guess you tried both inputs.
 
6267 tests good,,, brought Vp up to 250V,,, got over 20Vk... seems to be working, somewhat... There are a couple of broken wires,,, cap on treble pot has broken lead, and I don't see the other end close by,,, also has a lead off a resistor on a tag strip that goes somewhere... I believe B+ is working well enough thru the amp,,, signal is broken someplace...
I'll put the signal tracer on it tomorrow and see where it stops...
Think schematic in your gift giving!!!! AA 191 schem would probably be a good one to start with...
some chassis pics... Pot to the Right is treble,,,they are all swinging on the wires...
 

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I'm a member,,, tried both inputs.. they are tied together with a resistor to ground, no slide switch to separate them...
 

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Wow! Your into it now and yeah the signal is broken somewhere and with a signal tracer you should have no problem figuring it out. I would then convert it back to aa 191 and install the switches as you already have the correct faceplate for it. I'd still like to know the origins of what was done to it as that other faceplate looks well done. Thanks for the schematic and it should be uploaded to the ak database as it seems its hard to find for free anywhere on the net.
I'm probally a member at that site come to think of it but can't remember my username or password lol
Anyways goodluck and keep us posted on your progress.
 
I'm not sure what BEA used/sold this amp for...Looks like they got it in kit form, and assembled it for their use, as the slide switches were never used, there are no holes in their face plates for them... From the catalog I found (1st post) they seem to be into supplying broadcast stations with gear... I don't think this amp has the crystal phono input that's on the 191 schem either, so they didn't need the selector switch on their end product...

Maybe I should assemble the amp as a 191 from the schematic.... Or use the mods mentioned in the DIYAudio thread, with the selector and two line inputs,,, Thanks again for the input...

From the schematic, seems the broken cap on the treble pot feeds the grid of the output tube,,, that should make a difference!!!!

DIYAudio is a good site for tech stuff, like this,,, and I forgot to look there!!! Just get a new PW,,,,
 
Replaced the broken cap, and 560R(??) resistor at input jacks with 1M as on schem,,, no selector switch installed yet,,, Traced signal thru volume pot and cap,, comes out of EF86 low volume and very garbled... I have all the parts except for this tube, and it seems even tho it tested good (with questionable tester settings), it seems to be the problem...
There's a Hamfest in a couple weeks maybe I'll find one, or a couple there... Dead in the water for now,, unless I rewire it for a different driver!!!!!
 
Thanks for the offer,,,, over and above!!!! I just found that 6CW5 is a sub... I have two boxes of miniature tubes I got at Kutztown last week that I haven't looked thru yet,,, May be something in there.... I'll be in touch,,,
Thanks again !

EDIT,,, just realized I typed EL86 and got 6CW5 as a sub... should have been EF86/6267...
Gettin older every day!!
 
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Went thru the new batch of tubes and found an 8CW5,,, it tests about as well as the EL86 from the amp,, 85 /100... so I'm going to go thru all the caps and resistors before I condemn the tubes I have... Schem doesn't have Voltages, so best guessing with the RCA manual will have to do!!!! This is tightest, poorly designed box/chassis I can remember,,, pots have to be removed to access the chassis, and just swing in the breeze,,, its no wonder there are broken components...
Haven't given up yet...
 
Got it... Figured a bad tube was too easy!!! Think the problem was I didn't realize how low Voltage the 6267 runs,,, With 335V B+ into the OPT,, 6BQ5 gets 40Vk... However, 6267 Vp is 30V,,, Vk is .04,,, all readings to ground...
Any of these numbers seem reasonable?
Thanks for all the input and help...
 
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