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Oct 08, 2016 I purchased a Kenwood TS-790 from eBay. Neo geo games free for pc full version windows 7. How to initializing passport for mac. It was described as for parts only or repair -which if you read my occasional post's you will realise its how I like them! I've repaired three of these for others and I own one which I love. Kenwood TS-830S Transceiver SERVICE MANUAL. Free shipping. Original Kenwood TM-231A/E FM Radio Transceiver Service Manual. $22.95 + $3.99 shipping. Neobook crack serial key.
Sometime ago (in fact over nearly a year ago!) I purchased a Kenwood TS-790 from eBay. It was described as for parts only or repair -which if you read my occasional post's you will realise its how I like them !After search I found the TS-790 service manual and I started to study it. This rig has 2 independent receivers (main and sub) and as a result has also 2 IF's. The IF for the main receiver is 10,695 MHz and the IF for the sub receiver is 10,595 MHz. Download KENWOOD TS-790A E SM service manual & repair info for electronics experts. Service manuals, schematics, eproms for electrical technicians. Grumman maintenance manual. This site helps you to save the Earth from electronic waste! KENWOOD TS-790A E SM. https://best-poker-tools-for-mac2.peatix.com. Type: (PDF) Size 37.6 MB. Category AUDIO SERVICE MANUAL.
I've repaired three of these for others and I own one which I love. In the repairs I've carried out previously no PA blocks had failed but one had ALC problems (faulty diodes in the 144mhz section), one had poor soldering the PIN diodes of the PA and one had been transmitted into (!!!) and so needed the front end of the 2m section rebuilding.
This one was especially interesting as it had the rare UT-10 (23cm) module, the pictures of it showed that it was in a dirty state and un-loved, the sub receiver LCD display was not working. The advert did say that it received on 144Mhz (the only band they tested) but there was no output on transmit at all, the inference being that the PA blocks in TX section were blown.
So when the auction ended I found I had won it for a very, very good price, especially remembering the UT-10 module faulty or otherwise !!!
![Programming Programming](https://ae01.alicdn.com/kf/Hc6b09d6a183a496a88f2894ab499ee9bp/Ftdi-ft232-usb-rs232-adaptador-cabo-de-controle-gato-para-kenwood-ts-450s-ts690-ts-790.jpg_q50.jpg)
Upon receipt the 790 was as described - dirty, unloved and definitely in need of work but did indeed have the UT-10 module !
Initial testing proved the advert accurate, no transmit at all, it did receive (actually really well to spec on the Stabilock 4031) and the sub display was indeed dead.
Easy bits first - the Sub LCD display was working just not illuminated - the two 12v bulbs had were blown. I ordered (a long time ago!) 100's of the right bulbs with wire ends and current and so, 20 mins later the sub receiver was illuminated evenly and working nicely.
I also noticed that on SSB there was no ALC action at all, and regardless of the mike gain, the ALC was end stop (!).
At this point work intervened and I put it away for another day !
Fast forward nearly 12 months, my conscience pricked me and I had some time so I thought I'd take a closer look.
I started on the 144mhz, sure enough no output. I'm lucky enough to have a genuine service manual and so set about checking it against that, basic's first, voltages, tx switch voltages, all were OK. I went through the setup process, all were there or there, with a little adjustment all were put as per the service manual, but no output at all, checking the PA section everything looked fine. I disconnected the input to the PA stage just in case it should spring into life and to aid fault finding.
I checked again and the ALC on SSB was end stop and so started to check the ALC area's of the circuit (below)
(Copyright Kenwood) |
It has a fairly standard approach to ALC with feedback from the PA sections being fed into the ALC board within the IF unit - its not unusual for this to fail, but the voltages were within reasonable levels. However on pin 7 of the unit the ALV should have been around .62v but there was none. Checking where this is derived from the 'SW' unit which turns out to be the RF power and Mike control board.
So I have a close look at the RF Power / Mike control, it seems very slightly loose (i'd assumed it needed the collet ring tightening up) but upon closer inspection its the pot itself. Now all have a little movement, but this seems slightly more that usual.
I remove the board from the front panel and have a closer look. The front of the pot is definitely not quite right (see below)
So I de-solder the pot from the board and test it - sure enough the dual gang power pot (front one) is open circuit.
Luckily these are fairly often used in Kenwood kit and I know that I have one in a damaged front panel that I replaced on a TS-850 for someone else. - result !
I remove it from the panel, check its working (it was) and then put it in the SW board and re-assembled the front panel.
I check the voltages now as sure enough they are correct now, the ALC isn't end stop on SSB and so I reconnect the PA stage, connect to the Stablilock and sure enough there the right output that can be controlled by the RF power control.
Result - Fixed :)
So 144Mhz fixed and onto 433Mhz
Start again checking all the usual voltages and suspects - they are again all correct, I work back from the PA and check the input to it from the 433mhz RF section - there is an output (ie input to the PA section) but it seems very low (according to the service manual). I check and reset / tune the whole 433Mhz sections . PLL, 430Mhz section etc and get a massive output of 0.2w (200mW) output (according to the Stabilock !)
There clearly isn't enough output from the 433Mhz section to drive the PA blocks, so I disassemble the 430Mhz RF board so I can get to the bottom (all surface mount of course!) where the active components are and start checking the voltages vs the service manual (below is the section from the manual).
(Copyright Kenwood) |
Prior to this element of the circuit all the inputs and voltages on each active device were correct, I expected the final pre driver (Q244) to be faulty but the voltage were correct, working back I then checked Q223 - again all voltages correct, then Q222 (2SC3357) and found that the emitter voltage (.75v) was not present - I then check the bias components - all were OK, these are all SMT so I checked all the soldering - all were OK, so a possible faulty transistor.
I didn't have stock - so ordered up a replacement (in fact 5) NEC equivalents.
They arrived a couple of days later, genuine NEC ones (watch eBay for fakes there are lots of them!), I removed the 'offending' transistor with the hot air rework station, and replaced it then cleaned the flux off.
I re-assembled the board and tested the bias on TX and - nothing :(
Oh dear - I Then realised that in turning on and off the 790 I had selected 144 not 430 (!)
I then set the right band, and voila the right bias was present and the output of the driver board was about the right level.
Oh dear - I Then realised that in turning on and off the 790 I had selected 144 not 430 (!)
I then set the right band, and voila the right bias was present and the output of the driver board was about the right level.
I reconnected the 433 PA unit and there was the correct output.
I noticed on this 790 as with ALL the others I've seen there was no heat sink compound on any of the PA units and so I will ensure that there will be some before I finish,
I spent some time doing a complete setup from the service manual, and all was well
I noticed on this 790 as with ALL the others I've seen there was no heat sink compound on any of the PA units and so I will ensure that there will be some before I finish,
I spent some time doing a complete setup from the service manual, and all was well
RESULT - fixed.
Now onto the 1.2Ghz section.
TBC
Kenwood 790
Well, I needed to get back to my recently repaired Kenwood TS-790 as it developed a new problem. first ATV label (yes, there is an ATV label !) blinked from time to time, with no apparent reason and, sometimes, it kept lit for a long period. I checked schematics and got lost when trying to find the origin of the signal.But eventually it got worse: yesterday, while talking in a local QSO in 2m FM with the 790, I found a very curious thing. My 790 was SLOW to react to key presses, frequency change and even PTT!. Yes, there was a variable delay, from zero to some seconds, for the unit to execute what it was asked to do. Having worked for years in digital electronics, I thought the CPU was receiving some kind of interruption which made it work slow and even lose some commands or inputs to it. Immediately I thought of a backup battery leak damaging the circuit.
Here you have a low quality video of what happened. Sometimes dial is not updated but frequency changes. Also, F key is erratic:
So I got the 790 back to the workbench and, yes, there it was!. Battery, which measured a perfect 3.32V, had leaked and damaged some PCB traces below it. I don't know how I missed this when I fixed the unit!
This is what was below the battery.
I got the bad battery out, cleaned the acid residue and added a battery socket and a 2032 3V battery which is smaller capacity than the original one but lots easier to locate and, with the socket, a breeze to replace next time. I used Renata swiss made battery and holder as they are IMHO one of the best batteries available.
Note that the battery holder was not a perfect fit so I needed to add some wire to connect one of the poles to the PCB. But, all in all, it is lots better than the original soldered battery.
I tested the rig and it worked almost flawlessly. Yes, there is now a different fault which I need to further investigate. Now ATV icon does not light and rig reacts fastly to keypresses, PTT and such. But now ON AIR LED is sometimes behaving strangely: it sometimes does not light and sometimes keeps on even when PTT is not active (but rigs go to TX and RX as it should). So I need to check carefully how ON AIR LED is activated and check the unit to locate the fault. I will do it when I install the
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