Author Topic: Intermittent low level TX audio IC-7100  (Read 4983 times)

G3TKF

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Intermittent low level TX audio IC-7100
« on: 2021-04-11, 01:23:12 »
Hi all

I've been using the RR-1258 for nearly 3 years now with my IC-7100 but recently started to lose transmit audio on SSB and FM.

Tx audio (SSB and FM) dissappeared 6 times during a 3 hr VHF (50Mhz) contest tonight. Using N1MM as logger and controlling radio , head in the home shack and body of radio at remote.

When the fault is on, audio sometimes can JUST be heard with a low level clicking (almost a purring sound). The low level audio obviously producing very low RF output on SSB.
Deviation on FM is also very low or non existant in the fault condition .
I have changed the IC 7100 radio as I have a spare - both ends ...the fault still occurs.
I've changed the microphone.
No issues on Data or CW. It's as though the radio "Data Off Mod" is switched to USB and not MIC - it's NOT though!
Resetting either control or radio resolves the problem for around 5 or 6mins then the problem re occurs. ... switching off the remote 12v does the same.

Without the fault, the system works very well.

It's beginning to look like a RR-1258 unit fault (snr 11960) but would love some advice.

Any ideas greatfully accepted !!

73
Robin
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sm2o

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Re: Intermittent low level TX audio IC-7100
« Reply #1 on: 2021-04-11, 09:23:34 »
I have never heard that this have happen before. A few times codec settings has changed to 0 and the user says he has not change anything, but then it has been permanent. reset does not help, the setting must be changed back and stored. If this happen again, look at the codec settings in the RRCs. You can also try to change RTP tx mode to "continuous" in the Control-RRC then no writing is done to the codecs when shifting from RX to TX.

73 de mike

G3TKF

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Re: Intermittent low level TX audio IC-7100
« Reply #2 on: 2021-04-12, 15:28:08 »
Thanks Mike

I don't think it's a codec switching issue as it can (frequently) happen in the middle of an "over" and just fades out over a second or two, but at other times it is immediatly there on TX.  I've changed RTP tx to continuous but again as it can happen mid over I don't think that's it .

It's like bias on an op-amp is fading or maybe a voltage regulator - but I've changed the radio and still have the same issue.

Any other thoughts / ideas please ?

73
Robin
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sm2o

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Re: Intermittent low level TX audio IC-7100
« Reply #3 on: 2021-04-12, 15:31:56 »
Hi
There is no other active component involved than the codecs. If it's not a digital issue I guess it's just a bad red strap connection

/mike

G3TKF

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Re: Intermittent low level TX audio IC-7100
« Reply #4 on: 2021-04-15, 13:17:52 »
Thanks Mike ...
Well I have checked the red straps and reseated each one, having cleaned the links ...
After 10mins or less of operating the audio fades away to virtually nothing in the middle of an over - FM or SSB...

73
G3TKF
« Last Edit: 2021-04-15, 13:26:54 by G3TKF »

sm2o

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Re: Intermittent low level TX audio IC-7100
« Reply #5 on: 2021-04-15, 19:46:04 »
Hi

there is schematics on page 234,236 in the manual. There is only a few components beween the codec and connector and non is active. if you check the version of the pcb i can send you placement drawing 1258B-7 meaning it's version 7 as an example. Have you tested with another mic ? I still doubt it's realted related to Remoterig hardware as I have never heard about it before. And after 10 years I think I have seen all that can happen

/mike

G3TKF

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Re: Intermittent low level TX audio IC-7100
« Reply #6 on: 2021-05-06, 15:33:42 »
Hi Mike
Thanks for the reply ...

The fault is still intermittently there unfortuantely .... I guess I will have to bring the two units into a repair area to check ...
Yes I have used several other mics ! It is NOT a mic issue....

I don't understand your comment ""There is only a few components beween the codec and connector and non is active""
Surely if component C65 or C81 on P234 for example went faulty there could be a loss of audio ???

Perhaps you could email me the placement drawing 1258B-7 which may help .... many thanks Mike
73
Robin

sm2o

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Re: Intermittent low level TX audio IC-7100
« Reply #7 on: 2021-05-06, 19:10:44 »
Hi
Resistors, capacitors are normally referred to as passive components. Op-amps transistors etc, active components.

Resistors and capacitors do no use to break intermittently if the are not mechanical broken

but if the audio fade away, check that the bias voltage to the mic is not changing

I attach placement drawing for 1258B-7

73 de mike

G3TKF

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Re: Intermittent low level TX audio IC-7100
« Reply #8 on: 2021-05-07, 00:07:17 »
Thanks Mike

I will connect the units together on the bench with only a router/switch - hopefully that will produce an answer .
I have two IC7100 radios - I have changed them over including all associated leads .... the same intermittent audio fault is with both radios... it is not a mic bias problem.
To elaborate slightlly on previous coments...
When the fault is evident ,resetting either control RRC or radio RR via the PCs resolves the problem for around 5 or 6mins then the problem may re occur. ... switching off the remote 12v supply does the same - turning the RADIO on or off does not clear the problem....

If I connect via Icom Remote Utility and RS-BA1 there is no problem (but no useable CW either !)

Thanks for the placement drawing and continued assistance.

73
Robin
« Last Edit: 2021-05-07, 10:52:12 by G3TKF »