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 Post subject: Eton Grundig Edition Field BT multi-band radio project...
PostPosted: Aug Tue 16, 2022 5:20 pm 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Hello All,

Realize that this isn't a "vintage" radio, but it does contain thousands of transistors and hopefully someone here might be familiar with them...

Picked up this non-working radio at our local radio club meet this past Saturday for $5. Very good cosmetic condition. Got it home, detail-cleaned and radio functions seemed to work as far as display (except no DSP info on FM). Plugged in headphones and heard audio and radio began working. Unplugged headphones and radio worked well except for intermittent shut-downs when tuning quickly. Then all worked fine for remainder of day---listened to SW late at night. Next morning, back to "square one" with no sound other than "beeps" from controls and cannot get anything even with headphones this time. Appears that radio circuit is failing as it doesn't seek or display the DSP info on FM as it did before, and no S-meter activity. Bluetooth works for short time then shuts down.

Pulled main and side control PCB's this morning and already see a questionable solder connection on a small module which I need to identify. Does anyone know if there is a schematic for these anywhere ??? Found nothing on-line but the owner's manual and spec sheet...


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ARF ETON 8-16-22.jpg
ARF ETON 8-16-22.jpg [ 660.99 KiB | Viewed 979 times ]


Last edited by xrhonda91 on Sep Fri 09, 2022 4:48 am, edited 1 time in total.
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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Wed 17, 2022 3:19 pm 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Realized soon after posting that it is the Bluetooth module with the questionable solder connection at a ground terminal. Late last night found an article on-line which identified the radio "chip": https://www.osengr.org/Projects/Eton-Ha ... Hack.shtml

Then downloaded the 40-page datasheet for the Si4735 which will enable troubleshooting and "reverse engineering" of circuit if necessary: https://www.skyworksinc.com/-/media/Sky ... 5GE9eA-JlA

The other IC's are common and datasheets easily available...

Multiple projects here including another radio, house, car, and finding another used iPhone as mine died, so may be awhile until I can spend the needed hours to troubleshoot this, but will continue to post any progress... Always interested in others input !

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Fri 19, 2022 4:23 am 
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Joined: Dec Tue 07, 2021 3:28 am
Posts: 98
Location: Des Moines, WA
Location: Des Moines, Wa
Many of the Eaton portables were either made by Tecsun or Tecsun bought them from the same manufacturer. Either way, you may have better results in your search for documentation using Tecsun + field + radio + BT and so forth. I found the schematics for the Satellit 800 labeled as a Tecsun HAM2000.

Michael


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Fri 19, 2022 4:45 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Thanks Michael---will give that a try !

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Tue 23, 2022 3:21 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Along with many hours earlier, spent all day yesterday working on this headache. Completely disassembled and examined every solder connection. There were several bare wire jumpers on the processor/display or "keyboard" as Eton calls it that were laying directly on top of PCB traces. Even though solder-masked, I've seen cases where the mask was chipped or scratched and caused intermittencies with such positioning. Removed all these jumpers and added white Teflon insulation. Also found several "solder splashes" and near bridges at a few connections which I carefully removed. Put it back together and it did work initially, but would still intermittently not turn on radio unit. Going over all connections again, decided to check continuity on the communication cable to radio board and found one line which was extremely erratic when moved and another which was lesser so. Very gently pulled wire at processor board connector terminal and it slid out easily---bad crimp !!! Have seen this many times during my career as an Electronic Tech, so wasn't that surprised, though was excited to finally find something which could definitely cause the experienced failure ! Went ahead and carefully snapped off all the tiny plastic terminal locks on housing and soldered ALL the wires at connector. Verified all connections were solid and that there were no shorts before reassembling. The excitement was building that the problem was finally solved and when I connected power and pressed button, the #$&! thing didn't work !!! ARGHHHHH !!! Display did come up, but now display didn't always even display "on" and even the tuning activity was erratic or non-existent ! Must have damaged the cheap Chinese "black-blob" processor somehow ! Possible that I caused an ESD event, though I tried to be careful and it seemed too humid in house for a charge to develop so didn't ground myself as I would when dry in the winter. Very angry and disgusted after so much time and effort, but still continued to look for other faults I could have caused but found none---even pulled shield and display module again to look at processor circuitry beneath. All looked fine... So back together and on the shelf it went---still debating on trying to find parts, modifying with different processor, or passing it on to someone else to play with. Maybe I'll run across another junker with different problem to salvage needed module...

Few pics below...

John


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ETON PROC-DISP PCB JMPRS INSULATED 8-22-22.jpg
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ETON PROC PCB BK CONNECTOR SOLDER ALL 8-22-22.jpg
ETON PROC PCB BK CONNECTOR SOLDER ALL 8-22-22.jpg [ 573.03 KiB | Viewed 762 times ]
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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Tue 23, 2022 11:06 pm 
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Joined: Jan Tue 31, 2012 12:55 am
Posts: 21367
Location: Bryansford Village. Ireland.
I would dig a big hole in the backyard and give it a good send off with a few words offered to the radio gods, and maybe have a beer afterwards.
You could always place a marker, here lies the body of a poor little radio. lol

:) Greg.


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Wed 24, 2022 3:33 pm 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Greg, it sounds as though you are "under the influence"... How could you even consider trashing such a fine looking set even if it does have the infamous, cheap "black blob" heart ? This could be a real but frustrating exercise in digital engineering ! Already thinking of simulating the needed inputs for radio chip with old laptop (and other necessary circuitry) just to see what happens. Could be fun ???

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Wed 24, 2022 10:53 pm 
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Joined: Jan Tue 31, 2012 12:55 am
Posts: 21367
Location: Bryansford Village. Ireland.
"under the influence"

Wrong...
don't drink, don't do drugs, don't buy Chinese radios.


:) Greg.


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Thu 25, 2022 12:08 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Greg---I don't drink, smoke, do drugs, or engage in any other unhealthy or immoral activities (other than get stressed and angry way too easily). Saw the mention of "beer" and thought you had possibly "tipped a few" ! Guess I just couldn't pass this up for $5... Regretted even that after the frustration it's caused, but trying to turn it into a "positive" challenge...

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Thu 25, 2022 12:47 am 
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Joined: Jan Tue 31, 2012 12:55 am
Posts: 21367
Location: Bryansford Village. Ireland.
It would frustrate me too John. lol

I really don't know what to suggest as I usually don't work on radios manufactured after the mid 1970s... 8)

If any of those small I.C.s are BGA, maybe reflow them?
The encapsulated one I'm not so sure of, I've only seen them inside early quartz wristwatches and greeting cards.

I looked on the bay, and the cheapest parts set was around 60 bucks.

Don't let stress get to you buddy, it can have bad/negative effects on the body. Years ago, and still sometimes today, if something really irks me (which is not very often), I visualize a regular wall plate light switch, and… quickly flip it to the OFF position.

If you haven't got a rework station, maybe pull the caps and any removable plastic/rubber parts and bake the boards in an oven.


Greg.
oh… I always remove the smoke-alarm battery when baking. lol


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Fri 26, 2022 2:59 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Thanks Greg !

Thankfully no BGA chips.

Got the scope out tonight and checked the suspected data lines to radio chip---the outputs of the "black blob" were definitely degraded---lower level than what they should have been and distorted (about 2V P-P). Noticed when I touched data pins with scope probe that it began to respond more to the control buttons, so thought I'd play with a pull-up resistor just to see what would happen. The "blob" already has 150K SMD pull-ups on data lines, so grabbed a 68K to see what effect it might have. The amplitude of the data dropped to around .5V, but it was now clear & crisp---and the controls began to function as normal, but the level was too low to "talk to" the radio chip, so no "radio-activity". Behavior basically what I saw before. Next step is to look into an OP-amp buffer to raise levels to where they should be to communicate with radio chip---shouldn't be too difficult to try... Just hope the Si4735 radio chip wasn't also degraded during handling ! Any of you digital Guys have any suggestions ???

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Sat 27, 2022 12:32 pm 
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Joined: Sep Mon 05, 2011 12:42 pm
Posts: 1104
Location: Philadelphia, PA
I have the non-bluetooth version of that radio.
It has lots of very funky intermittent problems - switches to shortwave when it's set to FM, flickering display, changes the frequency without me touching the tuning dial, won't remember settings (like turning off the "beep"). It acts likes it's possessed.
I only keep it because it's the only portable radio that I currently own that has shortwave.

_________________
Dan
N3DTF


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Sat 27, 2022 2:54 pm 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Thanks Dan,

Yes, even when it starting working for that one evening, it behaved oddly for awhile until it "settled in" and performed welll for a few hours without fault. Sure wish I could find a schematic or even a good block diagram of entire radio for reference. I still think powering that radio chip at 2.4 Volts when the datasheet for chip states that analog portion requires a minimum of 2.7 ! Think I'm going to carefully put 1M pots as pull-ups on each of the data lines and see just what resistance is necessary to "clean up" appearance of data on scope. Just hate to admit defeat !

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Mon 29, 2022 3:45 pm 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
"Played" with pull-up resistances on data lines last night as well as "reverse engineered" communication connections to identify. Appears that the data output of "black-blob" processor is degraded as even a megohm of resistance as pullup reduced the amplitude, though it did clean up signal enough that the unit would power up & down normally and change functions (still no "radio-activity"). Bluetooth now works great, so could at least use it as an amp/speaker for iPhone...

But as I had it on awhile in radio modes with headphones, noticed intermittent "pops" and "hissing" like earlier though it never came to life "radio-wise". Watching scope closely, I saw the data level increase noticeably in amplitude as these "events" occurred ! Wish I'd had access to other processor pins to see if cause was internal or external to chip. Plan to play a bit more with it now to see what happens ! Need to see if there is a simple device available to use with laptop to examine the serial data being sent. Still searching for a schematic...

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Wed 31, 2022 1:56 am 
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Joined: May Mon 25, 2020 6:37 pm
Posts: 1502
Location: Greater Boston, MA
Location: Greater Boston, MA
You are a saint for sticking with it this long!

I would have recycled/scrapped the thing in disgust a while ago!


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Aug Wed 31, 2022 4:32 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Hey Tym---just looks and sounded too good when working to give up easily...

Glad I took hi-res pics of processor circuit while LCD module was removed. Studied last night and discovered that there are 150K SMD resistors IN SERIES with the two data lines at the "black-blob" processor module ! No wonder the "experimental" pull-ups had so much effect on levels ! Was studying I2C bus circuits last night and these series resistor functions and values were discussed---typically in the hundreds of Ohms, so am baffled by the very high resistances used. Any digital electronics engineers here that can explain why those high values were used ? Maybe I'm overlooking something as I've been having bizarre problems with my old car also that are very frustrating and clouding my mind...

Other home projects on tap too with the cooler weather, so attention can't be focused for very long periods of time...

John


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 Post subject: Re: Eton Grundig Edition Field BT multi-band radio---schemat
PostPosted: Sep Tue 06, 2022 5:21 pm 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7637
Location: Indianapolis, IN
Took it off shelf the other day, did a bit more "reverse engineering" to understanding chips' functions, played with series and pull-up resistor values on data lines, and scoped more signals. The reset signal is clean & proper. The 74HC4066 is used to connect radio chip audio to amp when radio function selected. Couldn't get radio to work at all, though some of the data-line resistor combinations tried did cause "spurts" of audio output from chip, but no signals received even though tuning data was being sent. Found that the I/O line required a pull-up now for any of the controls to work, so discovered a 220K would allow reliable operation of processor and Bluetooth function. Bluetooth now works great and was surprised that I could carry radio around house and it would maintain reliable connection to iPhone sitting in another room. Just ordered a couple of the Si4735 radio chips in SSOP format (which operate down to 2.0 Volts analog) and a break-out PCB to adapt it to to circuit once I remove the original QFN part. If this doesn't fix it, am considering playing with an Arduino (something I've never done). Stay tuned !

John


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