Thanks. It was a real slogger and I still didn't really solve the problem just isolated it. Also learnt some good information about PLL circuits VCO's etc. Might be a while before i tackle another one though! Thanks for watching
I've come to this excellent series of videos a bit late in the day but I thought I'd add some comments. I've had the frequency instability problem for some years, though with the Kilohertz jumping about rather than the Megahertz. A quick fix (if the memory module is fitted) is to unplug one coaxial cable from the main circuit board. This takes the memory module "out of circuit" while still leaving it in place. This cures the frequency instability problem at the expense of not having the memory function. I *THINK* the problem lies with the memory recall ( MR ) switch on the front panel. I've just bought a "spares or repair" FRG-7700 off eBay and I'm going to swap the board that the memory recall switch forms part of so I'll let you know what happens. Although the switches in that area of the front panel are individual they are held together with a metal clip which I've tried and failed to remove so it's not easy to remove the MR switch for testing. I think the full scale meter deflection when tuned to 00.000 KHz is caused by the huge heterodyne - possibly the radio hearing itself? Regards, Lee Standley G0FCZ
Lee. Thanks very much for your interesting finds. I so wanted to actually track the faulty component but there comes a time when you just have to throw the towel in and call it a day. I would be very interested to see how you get on with yours. They are very good receivers and well worth keeping going. I have just finished repairing a Trio R1000 from the same era and that also had the huge heterodyne. I believe they are very similar in design. Thanks for watching and for your kind comments. All the best Graham M1GRA
Following on from my previous comments where I said I'd bought a "spares or repair" FRG-7700. I've now replaced the bank of switches on my FRG-7700 ( of which the (M)emory (R)ecall switch is a part of ) with the one from my newly acquired FRG-7700. This has completely fixed the VFO frequency instability problem AND another problem whereby when the MR ( *not* the Memory Store button ) switch was pressed, whatever frequency the VFO was tuned to at the time would be stored into a memory location. Graham: regarding the extra components on the underside of the memory module circuit board. According to the service manual this was to correct a 1KHz error in the memory frequency readout. Both the memory modules I have have had this mod done in the same way as the one in your videos, so I presume it was done by Yaesu on later production modules.
Thanks for all the info Lee and I'm glad you have sorted yours. Funny how a little switch can cause so many issues. Have you stripped it down to see if there's anything obvious inside that has gone wrong? Unfortunately I no longer have the set as it's has gone back to,it's owner but I would have liked to strip the switch out for a look. 73 Graham
I did enjoy that. I have one with a similar problem but I don't have a memory unit. It settles down after about 5mins so I am living with it for the moment.
Yours is almost certainly the VCO voltages. They do drift with age and eventually cause it to drop out. Might be worth going through it as the alignment is pretty straight forward on these. Glad you enjoyed the videos and thanks for watching.
Many thanks for the advice. I thought an alignment job would be the first thing to look out for. Not too technical myself but I think a guy at our amateur radio club could help me out on this. Would be so nice to get another 10 years out of the old girl. Have a shed load of modern stuff but I sure love the old frog. Thanks again. Larry The Pensioner Prepper.
Many years ago when I bought my 7700 second hand, I was told by someone who was "into FRoGs" that the 7700 is notorious for two problems: the PSU failing (even catching fire) and the memory module causing spurious issues. I gather that the first step when faced with spurious issues is to remove the memory module (if present).
James, that may be true. I'm experiencing tremendous amount heat on the Bridge and temporarily bolted a small heat sink with silicone paste in between. Nonetheless; upon checking the heat; it was recorded @160F. This could only be due to the Main Smoothing Capacitor ie: 6500mF dried up and become a resistor. I'd replace the Cap sooner and read the temperature. If the symptom persists, then the Bridge would be replaced with higher value (Amps) and bolted to the chassis. I will beat the system. My black box is perfect. All preset stations, functioning well. Replaced AA alkalines were replaced by Energizer Lithium Batteries. Cheers.
I will have a *GO* at stripping down the MR switch *IF* I can remove the clip that holds the four switches together. It reminds me of the spire clips that were used on domestic valve radios for holding, for example, speakers and trim in place. So easy to push on but a real pain to remove without breaking the lugs that the clips were pushed on to. If you see the air turn blue over Manchester you'll know I've broken something! I know from your videos that you've handed the set back to the owner but for myself, I do find the memory option useful for storing the frequencies I listen to most even if it is only twelve of them. Best Wishes, Lee.
I know what you mean Lee. They are a devil to get off. I tend to get a couple of very small flat screwdrivers and gently walk them off. I'd love to know how you get on and your findings. If it's fixable I could always ask Clint to pop the radio back to me for another look. All the best Graham
great videos well done for perservering , is it an expesive job having the radio aligned and new capacitors and rectifier replacing in the ac circuit ?
Interestingly I had the same receiver - I had no memory module attached. After it was turned on for a while and heated up, the frequency would drift all by itself. I believed that it was off frequency, it did a drift similar to what this video had on some selections. I never got to the bottom of it
Sounds like it might just need aligning if you are lucky. Have a look at the service manual if you have it. It’s pretty straightforward if you are confident
im having pretty much the same issue with it jumping from 5 mhz to 17 mhz and reading 17 mhz on several bands and the noise floor drops out when it does this. was there ever a determination what the actual problem was? im really not wanting to go thru the whole process like this video. you have extreme perseverance!
Thanks. The issue on this one I suspect was a bad ram chip in the memory module. Thre is also an IC in these that goes bad. So far I've done 3 with the same issue
Have been following your videos on this with interest Graham, as I plan to buy one of these on ebay (never quite know what you're gonna get!) for some more serious listening to replace my old CR100. Aah could have swarn it was those diodes earlier on - loss of the memory module no big deal though. I now have confidence to restore an FRG - can always use these videos as a reference :-). Cheers and 73s, Steve.
Thanks for the comments Steve. Strange that the memory module was causing the frequency error. They are lovely sets though and very well made. Frequency issues are normally an alignment issue which is pretty easy to do on these. Fingers crossed you will get a good one. This site was a great help foxtango.org/frg7700/FRoG-7700.htm Good luck 73 Graham
I've enjoyed the full video series, great job! Have two of these frogs, both suffer from that switch-knob issue, it crackles much when ssb or noise switch/pot is operated. Your video journey made me think to go through such adjustment as well - as dial and shown frequency already are out of sync, too, etc. Thanks for such great vids!
0410hrs March21,2020 California Thanks for the video. Very impressed on your LSB SW reception. Would like to know the time, Loc, Dt: and the type of Antenna from your log. Watched the end user's video also and his remarks on your service. Cheers.
Hi . I had bought one modified from Surrey Electronicas, and I had no sound and the frequency stuck at 39.950 MHz in the bands from 20 to 29. After some investigations and changed all the electrolytic caps the radio is now working perfectly.
Excellent production Graham you done a great job there very well documented super clear picture. Thanks Graham
Thanks Les. It was a tough one to sort but got there eventually.
Really enjoyed watching this series. You deserve the prize for perseverance!
Thanks. It was a real slogger and I still didn't really solve the problem just isolated it. Also learnt some good information about PLL circuits VCO's etc. Might be a while before i tackle another one though! Thanks for watching
I've come to this excellent series of videos a bit late in the day but I thought I'd add some comments.
I've had the frequency instability problem for some years, though with the Kilohertz jumping about rather than the Megahertz. A quick fix (if the memory module is fitted) is to unplug one coaxial cable from the main circuit board. This takes the memory module "out of circuit" while still leaving it in place. This cures the frequency instability problem at the expense of not having the memory function.
I *THINK* the problem lies with the memory recall ( MR ) switch on the front panel. I've just bought a "spares or repair" FRG-7700 off eBay and I'm going to swap the board that the memory recall switch forms part of so I'll let you know what happens. Although the switches in that area of the front panel are individual they are held together with a metal clip which I've tried and failed to remove so it's not easy to remove the MR switch for testing.
I think the full scale meter deflection when tuned to 00.000 KHz is caused by the huge heterodyne - possibly the radio hearing itself?
Regards, Lee Standley G0FCZ
Lee. Thanks very much for your interesting finds. I so wanted to actually track the faulty component but there comes a time when you just have to throw the towel in and call it a day. I would be very interested to see how you get on with yours. They are very good receivers and well worth keeping going. I have just finished repairing a Trio R1000 from the same era and that also had the huge heterodyne. I believe they are very similar in design. Thanks for watching and for your kind comments. All the best Graham M1GRA
Following on from my previous comments where I said I'd bought a "spares or repair" FRG-7700. I've now replaced the bank of switches on my FRG-7700 ( of which the (M)emory (R)ecall switch is a part of ) with the one from my newly acquired FRG-7700.
This has completely fixed the VFO frequency instability problem AND another problem whereby when the MR ( *not* the Memory Store button ) switch was pressed, whatever frequency the VFO was tuned to at the time would be stored into a memory location.
Graham: regarding the extra components on the underside of the memory module circuit board. According to the service manual this was to correct a 1KHz error in the memory frequency readout. Both the memory modules I have have had this mod done in the same way as the one in your videos, so I presume it was done by Yaesu on later production modules.
Thanks for all the info Lee and I'm glad you have sorted yours. Funny how a little switch can cause so many issues. Have you stripped it down to see if there's anything obvious inside that has gone wrong? Unfortunately I no longer have the set as it's has gone back to,it's owner but I would have liked to strip the switch out for a look. 73 Graham
I did enjoy that. I have one with a similar problem but I don't have a memory unit. It settles down after about 5mins so I am living with it for the moment.
Yours is almost certainly the VCO voltages. They do drift with age and eventually cause it to drop out. Might be worth going through it as the alignment is pretty straight forward on these. Glad you enjoyed the videos and thanks for watching.
Many thanks for the advice. I thought an alignment job would be the first thing to look out for. Not too technical myself but I think a guy at our amateur radio club could help me out on this. Would be so nice to get another 10 years out of the old girl. Have a shed load of modern stuff but I sure love the old frog. Thanks again. Larry The Pensioner Prepper.
Graham you are a true craftsman.
Glad you enjoyed it. Thanks for watching. Graham
Many years ago when I bought my 7700 second hand, I was told by someone who was "into FRoGs" that the 7700 is notorious for two problems: the PSU failing (even catching fire) and the memory module causing spurious issues. I gather that the first step when faced with spurious issues is to remove the memory module (if present).
In hindsight i really wish I had done that first. It would have saved me days of work. It did get a good overhaul in the process though
James, that may be true. I'm experiencing tremendous amount heat on the Bridge and temporarily bolted a small heat sink with silicone paste in between. Nonetheless; upon checking the heat; it was recorded @160F. This could only be due to the Main Smoothing Capacitor ie: 6500mF dried up and become a resistor. I'd replace the Cap sooner and read the temperature. If the symptom persists, then the Bridge would be replaced with higher value (Amps) and bolted to the chassis. I will beat the system.
My black box is perfect. All preset stations, functioning well. Replaced AA alkalines were replaced by Energizer Lithium Batteries.
Cheers.
I will have a *GO* at stripping down the MR switch *IF* I can remove the clip that holds the four switches together. It reminds me of the spire clips that were used on domestic valve radios for holding, for example, speakers and trim in place. So easy to push on but a real pain to remove without breaking the lugs that the clips were pushed on to.
If you see the air turn blue over Manchester you'll know I've broken something!
I know from your videos that you've handed the set back to the owner but for myself, I do find the memory option useful for storing the frequencies I listen to most even if it is only twelve of them.
Best Wishes, Lee.
I know what you mean Lee. They are a devil to get off. I tend to get a couple of very small flat screwdrivers and gently walk them off. I'd love to know how you get on and your findings. If it's fixable I could always ask Clint to pop the radio back to me for another look.
All the best
Graham
great videos well done for perservering , is it an expesive job having the radio aligned and new capacitors and rectifier replacing in the ac circuit ?
That memory module is actually capable of memorizing 256 frequencies. What limits it to 12 is the rotary switch.
Thanks. It’s a shame it had to go really. I suspect one of the ram chips had gone bad
Interestingly I had the same receiver - I had no memory module attached. After it was turned on for a while and heated up, the frequency would drift all by itself. I believed that it was off frequency, it did a drift similar to what this video had on some selections. I never got to the bottom of it
Sounds like it might just need aligning if you are lucky. Have a look at the service manual if you have it. It’s pretty straightforward if you are confident
im having pretty much the same issue with it jumping from 5 mhz to 17 mhz and reading 17 mhz on several bands and the noise floor drops out when it does this. was there ever a determination what the actual problem was? im really not wanting to go thru the whole process like this video. you have extreme perseverance!
Thanks. The issue on this one I suspect was a bad ram chip in the memory module. Thre is also an IC in these that goes bad. So far I've done 3 with the same issue
Have been following your videos on this with interest Graham, as I plan to buy one of these on ebay (never quite know what you're gonna get!) for some more serious listening to replace my old CR100. Aah could have swarn it was those diodes earlier on - loss of the memory module no big deal though. I now have confidence to restore an FRG - can always use these videos as a reference :-). Cheers and 73s, Steve.
Thanks for the comments Steve. Strange that the memory module was causing the frequency error. They are lovely sets though and very well made. Frequency issues are normally an alignment issue which is pretty easy to do on these. Fingers crossed you will get a good one. This site was a great help foxtango.org/frg7700/FRoG-7700.htm Good luck 73 Graham
Many thanks for that - will check that site out now, 73 Steve.
@@Radiocruncher What part number did you use as a sub for the Zener in the power supply? Can't hear what you said.
I've enjoyed the full video series, great job! Have two of these frogs, both suffer from that switch-knob issue, it crackles much when ssb or noise switch/pot is operated. Your video journey made me think to go through such adjustment as well - as dial and shown frequency already are out of sync, too, etc. Thanks for such great vids!
Good luck Alex and I hope the videos help. Kind regards Graham
Well I've enjoyed the whole journey cheers Graham from 2e0hcl
Thanks Glynn. Glad you enjoyed it. Graham
The bench has seen some ware since then ha
0410hrs March21,2020 California
Thanks for the video. Very impressed on your LSB SW reception.
Would like to know the time, Loc, Dt: and the type of Antenna from your log.
Watched the end user's video also and his remarks on your service.
Cheers.
Thanks Sree. I didn’t log it as it was only a demo. It was a female operator though. Always harder to tune in
You must endeavour to persevere.
Got there in the end. Thanks for watching
Hi . I had bought one modified from Surrey Electronicas, and I had no sound and the frequency stuck at 39.950 MHz in the bands from 20 to 29. After some investigations and changed all the electrolytic caps the radio is now working perfectly.
Nice one Filipe. Might be worth checking those VCO voltages as well. Regards Graham
Maddy and cocoa was pups then ha
If I ever get a7700 I'll send it to you lol 😀
Feel free Glynn. I think I have recovered enough from the last one now and learnt a lot in the process