I'm trying to repair a ESG signal generator. Error is most probably on board 4400 60002 where there are some MMICs marked 641. Does anybody has a CLIP or knows what type of MMICs this is? Could it be MGA-64135, (?).
There is also another ic at the output from this board. It might be U203 but I'm not sure. What type of IC is this? Golden flatpack with 8 pins.
The fault is that the 9V is badly loaded by this board and perhaps somebody has seen this error before?
I looked at the ESG again this weekend. Before I scrap the unit - does anybody have the E4400-90336.pdf?
Apparently this is with schematics and perhaps this would be the last chance for my unit. The ESG will be used for ham-radio experiments only so there is no commercial interest in this.
This time when I started it there isn't any text at all on the screen. It seems to get light on but the contrast/light can't be adjusted - computer failure too?
Did you ever succeed in locating all or part of the manual E4400-90336.pdf?
I too have a E4400B, this time with a suspected faulty pulse mod circuit,
I'm after circuit drawings for the A9 output board, & A11 reference board, (the ESG-A versions).
Again, the generator is for Ham Radio use, so unless I can locate the drawings, it will be beyond economic repair, shame as its a very nice generator, but I couldn't justify the 400usd on the full manual.
any info much appreciated at percival.harry(at)gmail.com
I'm sorry for a very late answer, but I'm normally not checking the signal source part of the forum.
I didn't found the E4400-90336.pdf and I would also use my generator for ham radio. My unit is scrapped and I couldn't get my hands on any spareparts at resonable prices.
This is most likely to late to help but I looked at the schematics and Yes the 641 is MGA-64135 The U203 is the final amp out. 9v driving it.
This board (p/n E4400-60002 Synthesizer) is available on ebay for 300 I repair these ESGs but for that price I'd just get the board and move on. maybe remove the final amp and see if supply comes back up.
I hope this helps.