Problem is, I just purchased a SBE console V -aka "sbe40cb". The transmit on ssb and am is fine and the receive on ssb is also ok. But the AM receive is very low, even at full volume. Also the scan seems to function but won't stop on a channel being used. I am not sure if I got one problem here or two. I am reasonably good with electronics as a hobby so I am sure I will understand any and all response however technical the response may be. The squlch seems to work ok. I am assuming at this point that the prob may be in the front end. I cannot find a service manual for it and have never before worked on this type of cb with scan. I have already done a serch here and have read remarks about the caps getting old and weak and the dry soldering joints. Maybe but I kinda think that maybe its a problem just before the audio amp but after the IF amp. Well then again, if I knew I wouldn't bee here looking for help.
Thanks in advance for any help offered here. Bobby
I will see if I can help but it has been a long time sense I last work SBE40, but I do have some notes from about 15 years ago.
This radio like all SBE suffers with cold solder joints and it not uncommon for them to require the tracks to be cleanup and complete re-soldering.
What is the voltage on the Emitter of TR803 (2SC1014)?
What is the voltage on the Base, Collector, and Emitter of TR402 and TR403 with the squelch CC and fully CW?
Check diodes D206 and D207 (1N60) know to go h/r, but this usual kills AM dead.
Is the signal meter showing a good signal on AM?
Hi Rick! Been reading lots of good things about you here.
TR803 (2sc1014) Emitter shows 9.55vdc
Can't seem to locate tr402 & 403. (still looking)
Signal on s meter is good
TR803 is ok that is the main voltage reg. Check C219 (160p) C220 (?) C221 (47u) and C222 (?) C223 (1u) D206, 207 (1N60) D208 (1N34A) D219 D220 (1N4148) any one of there components can give low audio; I am not saying that this is the fault but you need to start some ware. If you are in doubt about any of the components then replace them.
Transistor TR402 and TR403 are part of the squelch circuit.
TR403 E- .68 ccw .47 cw 2sc710
C- .66 1.06
B- .o1 .44 BTW, thank you for the warm welcome. If I had a bloody schematic or a service manual it would sure make things a bloody bit more easy.
Last edited by bobby4244 on Sunday 23rd Dec 2007, 13:20, edited 1 time in total.
Looks like you have low supply voltage on the AM RX line, check the voltage at each side of R406 (33K) the hot side should be about 9.3 to 9.5 vdc also check L202 (22u) for cold solder as the supply to R406 comes through L202, if the voltage is still low at L202 then check mode switch.
Thanks for the link NOMADRADIO, And thanks for sending the origional schematic for the SBE40CB RICK ! Its not fixed yet but I am confident that we are on the right track.
James, isn't the uniden madison the same or similar as that cobra 148?
The 148 GTL-DX was export radio some 30 years ago with 120 channels 26.515 to 27.855 AM/FM/SSB/CW and was not sold in the USA only in Europe. Must modern export radios are based on the 148 GTl-DX.
I tested the 6 diodes you told me to check.All seemed OK, to me anyway.
D206 (.388) D207 (.314) D208 (.427) D209 (.586) D210 (.592) .. I then went to the caps you told me to check. I only found two so far. the first C221 measured 5.3u and C223 didn't check right. I replaced it and guess what! THE AUDIO IS GREAT NOW ! You did it RICK !! The schematic that you sent me was a real life saver. Now the BAD NEWS : The scan still won't stop on an active channel. And I find it odd that when the squalch is fully counter clockwise it scans. But when the static is eliminated via the squalch control, it stops scanning. I would think that it should be doing just the opposite. Whats the next step Rick?
From memory the scan works some think like this, you adjust squelch control CW so the squelch just mutes the audio, then if you press the scan button the radio will scan until it finds a busy channel.
Rick, That sure sounds right to me. I tried it but no go. It won't scan unless I turn the squalch so its noisy. I never did check the other caps. Do you think that there might be another bad cap?
Thanks for sending the owners manual RICK. I though the scan was suppose to serch for busy channels. The manual you sent says that the scan serches for vacant channels. I guess back in the day, CB was so active that it difficult to find an empty channel. THANKS AGAIN RICK! The radio works perfect now.
Was I ever glad to find this thread in a Google Search!!!
I have had a Console V since wayyyyyy back. I pulled it out about a year ago to try to use it again and ....... no transmit. I had the Sams Photofact on the SBE Sidebander V which I believe is the same board. I was able to pin down that some of the switched TX voltages were missing but the Sams doesnt seem to have a pic that really shows the top level copper and my eyes went nuts trying to trace it.....so I gave up for the time.
The schemo here showed those top level traces well..... so I got out my Sams and started going back and forth between the two and now it makes real good sense. I can see how the switched votages connect.... so now I can track them from spot to spot on the board more easily.
This was a nice radio when it worked and now, thanks to you here, I have some hope again. I'm gonna go dig it out and get back to work!!!!
I have a few of these and the owners manual/ with schematic and yes, the scan is for Open channel only. 1 of mine has a problem, 1 of the channel digit readouts doesnt light 1/2 the segments. Anyone have this problem? Thanks, Ron
Well, I did find one of the top traces that was not connecting Transmit voltage to the final and the driver. I patched around it and..... well... it sort of worked. I now get transmit-switched voltage everywhere that it belongs.... BUT.... when I key using a power meter I see the very slightest of movement of the needle. If I switch to SWR and turn the calibrate all the way up the needle deflects about halfway. But, switch back to power, and it just barely moved to about a quarter of a watt....maybe. I really wish that I had a good 50 MHz scope ..... but I don't .... so I guess I'm dead in the water....for now anyway.
I dug up the 3 I had lying around and found that most of the problems where due to bad caps, especially the many 1uf electrlytics that this radio uses for bypass/blocking caps. Radio's had problems with very low or no AUDIO: rec, amtx and SSB output. Everything starting coming in line by replacing the caps, including in the compressor board. Also 1 had problems with 1 of the channel readout digits erratic. Acted like a cold solder, but resoldering did not help. Found that the 'resistor array' RA 801 had off resistor values. I removed it and soldered in 220 ohm resistors. Now works perfect, and these are pretty sweet radios.
can someone help me! my sbe console v has lost am modulation and on sideband very low modulation and low power
please email me at freilichmst@aol.com with your help, thanks marc
BTW, thank you for the warm welcome. If I had a bloody schematic or a service manual it would sure make things a bloody bit more easy.
