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Topics - VE1IC

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Got an older IC-7800 that has a blown PA to the tune that it needs a complete replacement board. It burnt the PCB crisp so the parts easily move on one side. It blew the 48V traces off the board, ugh. Seems to me I've seen a thread like that before a few years ago, or maybe I am day dreaming again. I am hoping that ICOM is still making this PA.

Other than that the unit does not power up, no stby light nothing. Some repair shop I don't want to name here in CDN had opened it and did some damage to the Ant. SW unit. I do remember that ICOM had problems with the early version PSU's. So I am hoping that the problem is due to the 48V being shorted (because of the PA) or the 15V rail or the -12V rail dead, anyway... something along these lines...

I am not really a stranger to big radios like that, but fixing this is gonna be $$$ and slow. Maybe call it my summer / fall project.

I've posted this over at badcaps too.

Got it as a X-Mas present from wifey. Lasted about 30mins and then it was absolutely dead.
Checked the PSU and it was loaded down to next to nothing. Unplugged the main board from the PSU and all is O.k. on the PSU. Ahh! Main board problem!
Took the main board out and find a short at T2 (78L05) regulator between the input and GND pin. Took that out including the cap that is next to it and still have a short. I also measured shorts between C53 and C57. Took these out, took the 2 IC's under that heat sink out and still a short! Running out of options I decided to go old fashioned way hunting a short. Feed Power! Fed 5V 1.2A on the shorted line, doused half of the board with alcohol and success! SMD cap C81 bubbling! Replaced that with another cap the same size I found on a TV main board, put that in, soldered in all the parts I had taken out, reassembled it and I've got a working Function Generator.

So in short: If you have a Feeltech / Kuman FY6600 that doesn't work and the PSU is good, check C81 on the main board. It is under that little heat sink that is on top of of the 2 IC's.

Merry X-mas!

Ham Radio Circuits and Repair / IC-751 PLL weird problem
« on: December 18, 2018, 08:34:07 AM »
I've got an old IC-751 here that has an interesting problem. For some reason the PLL will not go through frequencies correctly, even so the display sez it does.. The HPL and LPL tune proper as per service manual. What is happening is that the PLL will repeat a slot of 10khz 10 times to the next full 100khz through all bands all modes.
For example 10.000.00Mhz WWV. Everything that is receiving in the slot from 10.000.00 to 10.009.99 gets repeated on 10.010.00 to 10.019.99, then again from 10.020.00 to 10.029.99 and so on. It will do this to the next 100khz and it changes and repeats again like this:
So I will hear what is supposed to be between 10.100.00Mhz and 10.109.99Mhz, but that gets repeated every 10khz to the next full 100khz, also 10.200.00Mhz.
The display works fine, HPL and LPL on the PLL board are bang on, the voice module reads the same frequency than the display. The VCO works properly. I can see blips on the data lines for the HPL and the LPL  IC's when I turn the VFO, but it seems that one of the "swallow counters" isn't counting properly and does not allow the tuning voltage to go ahead and allow tuning from 10khz to 99.9khz. Wonder if anyone ran across this before?

New member welcome / Hello from Atlantic Canada!
« on: December 18, 2018, 08:09:36 AM »
Just want to say hello to everyone in here from FN63! I've seen a few of Buddy's vids on youtube and some threads on the EEV blog. As for me, I repair more equipment than I actually play with my on gear on the air.

73 all around, de VE1IC

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