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Mersberj
New member
Username: Mersberj
Post Number: 6
Registered: 8-2005
| | Posted on Sunday, October 16, 2005 - 10:20 pm: | 
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I started doing a supertune . Swapped the final (1969) and did the JP36 mod. That worked fine , so I wanted to complete the tune-up by adding/changing caps and changing resistor values. I think I added a cap to R55, C62 and 1 more which I can't remeber right now. I went to turn it on and key up just to see what I got so far and I got nothing. RX/TX light is normal but no meter movement on TX or power out. I added a talkback to try and see if the audio section was jacked up and I have audio out to that point. I removed all added components and rechecked . Still nothing.I took out of circuit and check C143,R56,C62,R58,C126 and a couple others that I cant remember also. Any suggestions on where to look next? Checked the final and PN junctions were good. Thanks for the help. |
Twowatt
Member
Username: Twowatt
Post Number: 65
Registered: 7-2005
| | Posted on Friday, October 21, 2005 - 11:53 pm: |
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the first thing i would suggest, is to take a scribe and go around all the places that you have soldered, from the final to the antenna wire to scrape up all of the flux - then clean with a tech brush (or toothbrush - then give it back to the xyl), and check for solder bridges.
also, just for funsies, verify that you have ~13v at the collector. |
Mersberj
New member
Username: Mersberj
Post Number: 7
Registered: 8-2005
| | Posted on Sunday, October 23, 2005 - 2:21 pm: |
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Did voltage check on the driver and final and this is what I got.
Final RX 0v 32v 0v TX 0v 20v 0v
Driver RX 0v 28v 0v TX 0v 12v 0v
Buffer Rx .671v .010v .004
Tx .777v .777v 2.96v
I am not sure which leg is base emitter collector( Source drain gate) but thoe vlotages are in respect to the transistor itself. |
Twowatt
Member
Username: Twowatt
Post Number: 67
Registered: 7-2005
| | Posted on Wednesday, October 26, 2005 - 11:18 pm: |
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first some quick fyi; "most" finals, the lead configuration looking from left to right (if you can read the numbers on the final) - base, collector, emitter. approximately "half" of the drivers have the same lead configuration.
now, if you did replace the jumper and everything else is put back to 'normal'; then the collector voltage on the driver & final should be within a fraction of a volt of each other, because they both get their voltage from the audio transformer T1.
do two things and get back with me: 1st, i hope you have a second cb that does receive. power it up and put it about 3-6 feet away from the 29 on the same channel (no antenna on 2nd radio). now key up the 29 and talk into it and see if you can hear yourself on the 2nd cb - if not, does the 2nd cb's meter move, or speaker noise change?
if you can hear yourself, then look for a bad/burnt/loose coil or a bad/broken solder pad or a cold solder joint: or you may have a driver or final bad, even tho the diode junctions checked OK. after checking all solder points and if the meter does move a little on the 2nd cb, here's an easy "might help find bad transistor"
tip: take either voltmeter (vm) lead, and key up the 29 and put the metal point on the base of the driver and see if the 2nd cb's meter goes up in signal strength - if not, the problem may be between the buffer & driver. if the 2nd cb meter does go up, then move vm lead to collector of the driver; there should be an increase in signal strength - if not, possible bad driver. next move vm lead to base of final and the 2nd cb meter should be about the same, maybe a little less - if a lot less, then check caps, resistor and coils between driver & final. if the 2nd cb meter reading about the same, move vm lead to collector of final, and you should see a decent increase of signal of 2nd cb's meter - if not, may be a bad final. if a good increase, use the vm lead and go to each side of c60, L14, L13, L12 all the way to the wire from the circuit board to the antenna connection to see where the signal on the 2nd cb's meter drops way down; and that will narrow the problem area.
if you can't hear yourself, turn the mike gain all the way down and key the 29 and check dc voltages again, and also check for AC voltages in the TX mode. the dc voltage on the driver & final collectors should be 12-13V depending on power supply and about the same voltage. the AC volts you may or may not be able to see on your voltmeter, but should be about .6 - 1 V on the bases. (if not, use the vm lead bad transistior find tip)
hope this gets you started. |
Therealporkchop
Intermediate Member
Username: Therealporkchop
Post Number: 425
Registered: 11-2002
| | Posted on Thursday, October 27, 2005 - 12:23 am: |
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I'd recheck where you did the JP36 mod. You might have that wrong and that will effect whether or not the radio keys and has any output. You can also experiment there and change the deadkey of your radio.
Depending on where you got your 1969 you could have gotten a dud. There was an internet site where you could buy them real cheap. So I did, and found out they were something more like 2078's that had be silkscreened to a 1969. Also on a popular auction site there is a guy selling them and they ARE NOT the real deal. They won't hardly put out any more power than a driver will. So if you got them there you might want to check them out. |
Big_rigger
Junior Member
Username: Big_rigger
Post Number: 19
Registered: 8-2005
| | Posted on Tuesday, November 01, 2005 - 3:01 pm: |
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CAN SOMEONE TELL ME WHERE JP36 WIRE GOES PLUS THERE IS A WHITE WIRE NEXT TO IT I COULD SURE USE THE HELP |
Twowatt
Member
Username: Twowatt
Post Number: 68
Registered: 7-2005
| | Posted on Wednesday, November 02, 2005 - 12:12 am: |
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Big rigger,
is your jp36 jumper gone?
on the board, there is some white writing (called silkscreen) that says jp36, and there are 2 white lines going away from the number "JP36"; at the end of those lines, are the thruholes where the wire jumper goes in and is soldered to those 2 holes.
hope this helps. |
Chad
Advanced Member
Username: Chad
Post Number: 546
Registered: 11-2004
| | Posted on Wednesday, November 02, 2005 - 9:08 am: |
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With the radio facing you it can be found running perpendicular to the front/rear along the heatsink for the final and to the left of the larger tuining coil that is to the right of the final on your side of the heatsink.
Chad |
Big_rigger
Junior Member
Username: Big_rigger
Post Number: 21
Registered: 8-2005
| | Posted on Monday, November 07, 2005 - 3:16 am: |
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THANKS TWO WATT BUT THEY ARE HOOKED UP WHERE JP36 ARE SOLDIERD IT THE OTHER END WHERE I NEED TO KNOW THE WIRES GO |
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