Sommerkamp ts-2000dx no tx audio (same as old rci 2950)

[jstahnke]

I have been off air for about 10 yrs and recently bough this radio off ebay. It rx's fine, but no tx in any mode???? I used to tinker around inside radio's , but im pretty rusty. One thing i noticed upon opening was that 2 of the 3 jacks that plug into the mic pcb have 1 wire snipped at the base. Is this worth investigating or is it snipped from the factory. PLEASE HELP!!!!! THANKS IN ADVANCE FOR ANY AND ALL HELP!!!!!!!!!

[Rick]

Do you have a TX carrier on AM and FM mode?
Is it just case of no TX audio on any mode.
Also please read the info on the link below
www.radiomods.co.nz/forum/viewtopic.php?t=312

[jstahnke]

Yea, it is putting out a signal, just no modulation, Thanks alot for the help!

Do you have a TX carrier on AM and FM mode?
Is it just case of no TX audio on any mode.
Also please read the info on the link below
www.radiomods.co.nz/forum/viewtopic.php?t=312

[Rick]

You do not need to use the Quote.

Check from Pin 2 on the Mic socket back to Pin 3 White with Screen cable of J110, J110 Pin3 is link to Pin 1 on J112 which go to one side of the Mic Gain control and centre from the Mic Gain control back to the Red wire on Pin 2 of J112.
Hope this helps.

[vintagetech]

Do you have a TX carrier on AM and FM mode?
Is it just case of no TX audio on any mode.
Also please read the info on the link below
www.radiomods.co.nz/forum/viewtopic.php?t=312

[vintagetech]

Since this radio uses a separate modulator circuit to modulate the final section a simple method of checking the audio circuits is to try the PA function this will allow you to check the audio line and make sure the mic wiring is good. If you have audio on the pa section you know that the mic as well as the modulator for the receiver is fine. Check and make sure you variable power adjustment from the front pane rf power control you should have a smooth control from about 1 watt or so up to maybe 10+ watts if this works you then know the regulator is functioning that supplies voltage to the collectors of the drivers and finals. You know that regulator is not being modulated by the 4558 chip we already know this chip is working if the PA function is working and this help narrow the problem down. let me know what out up to this point and I will be glad to help you troubleshoot it from there.

[Rick]

The original TS-2000-DX do not have a PA function.
That why I went down the route I did.

[vintagetech]

Hello Rick

I wasn't sure although I have repaired this radio in the past the units I have seen all had the PA function. It's always been a real challenge troubleshooting equipment in this arena, It's tough enough when you have everything you need at your disposal. I'm just an old man that thought I might be usefull in some way. I will be interested in watching and finding out what the final conclusion is with this old unit and maybe I will offer my insights along the way. Thanks for the reply Rick.

Dennis

[jstahnke]

The wires snipped are the black wire from the 3-pin PCB jack on the mic board (which goes to a board mounted to the front panel board) and a yellow wire coming from the 2-pin PCB jack directly above the previously mentioned 3-pin jack. (I traced this back to the same area as the other snipped wire on that front panel side board.) Im not sure why this guy snipped these wires, but im starting to think it is the problem, but where can i buy 2 and 3 pin jumpers (or atleast the jacks) I can splice because they are cut RIGHT at the base of the those tan-brownish jacks)

[Rick]

If you check my Sch diagram on CBTricks you should be able to work out where the wiring should go.
http://www.cbtricks.com/radios/rci/rci_ ... 50_sch.pdf
http://www.cbtricks.com/radios/rci/rci_ ... wiring.gif
Hope this helps, let us know how you get on.

[jstahnke]

Thanks alot for the charts, one glance and i see that those wires ARE cut from the factory. Id still be fumbling around without your help. Anyway, i prdered a new multimeter and tools on ebay, and as soon as they get here in the next day or two, i guess ill just start tracing the whole TX audio circuit. Im pretty rusty on my tech skills, but hopefully its something obvious that i can easily repair. On a side note...ive been searching the internet lately in regards to the hobby, and i have to give you your props. From what ive found, you are one of..if not THE MOST informative, helpful, and knowledgable people on the net regarding this hobby. Reading some of your past posts had a direct effect on me deciding to get back into radio. KEEP IT UP MY FREIND!!!

[jstahnke]

OK, so i checked the voltages on most of the mic audio circuit, and they seems to be severely out of wack starting as soon as the IC16 mic audio amp. Does anyone have any ideas on if maybe this chip should be replaced? I have been lookin ALL OVER the internet for the pinout info for ic16 (JRC4558D) and have come up empty. I have no idea where to go from here???? I would hate to order a new chip if its not the culprit. Thanks again to rick and everyone else!

[Rick]

Have you check the radio for TX audio on SSB?
What voltages do you have on Pins 1, 2, 3, and 8 in TX?
An all too common fault over look is C141 (.22uF).

You can check in you have any Mic audio up to the Mic Op-Amp IC16 with an old ear bud.
Just cut the plug of the end and strip the wire back. Then connect one to ground (a tuning can is best) and connect the other wire to the Collector of Q32, the level of Mic audio will be very low but at least you will know you are getting Mic audio.
If the Roger beep is switched on you should be able the hear it when you de-key.
If you have on Mic audio check Q32 I have had them go short Collector Emitter.

[jstahnke]

OK, So i didnt have an extra pair of headphones around, but i can tell there is some sort of audio output because i can here myself very lightly when in PA mode. I temporarily removed q32 (made no difference) and c141 is working sufficiently. the readings taken from the ic16 is as follows:

pin 1 = 2.8v in tx on AM
pin 2 = 3.5, but then jumps around very spuratically
pin 3 = 2.8v tx in AM
and pin 8 = 1.5v TX in AM

By the way rick, to answer your question, yes there is no audio on AM/ FM OR SSB. Thanks for all your help!

[Rick]

It looks like you have lost the volts at Pin 8, it should be about 8 to 8.50 vdc.
Check each side of R156, if the volts are ok on the hot side of the R then its likely that C138 is short or IC16 is bad. Also look out for cold solder joints.

The voltage at IC16 should be:
All readings in TX Mode
Pin 1 = 4.50 vdc
Pin 2 = 4.50 vdc
Pin 3 = 4.50 vdc
Pin 8 = 8 to 8.50 vdc