(Wanted)  Grundig/Digimess PN300 schematics - Page 1
Forum section: electronics / general

author: amiq
author_rank: Regular Contributor
timestamp: October 23, 2018, 06:07:58 am
content: Anyone have schematics for the Grundig PN300 supply? Digimess can supply a full service manual but it's not cheap (£40).

author: Fraser
author_rank: Super Contributor
timestamp: October 25, 2018, 10:04:29 am
content: I have the PN300 schematics on order. I hope to have them today.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: October 26, 2018, 12:08:40 pm
content: I now have the PN300 schematic but I had to buy it so a small contribution to its cost would be welcomed.Fraser

author: Burner_357
author_rank: Newbie
timestamp: October 27, 2018, 09:21:21 pm
content: I also have the service manual with all the schematics for the PN300 as pdf file.And I have the full service manual for the PN200 as well.If you're having problems with your unit, my expieriences may help, as I have several of the PN300s and all of them had the same kind of issues:One or more of the following faults applied to either one, or both of the channels:1. Output voltage with no load at the output is a few volts below the set value, or the output voltage is only about 1V anyway.2. Output voltage drops a lot, when output is loaded.3. Output voltage is constantly jumping around when a constant resistive load is attached to the output4. Output is clamping at the CC limit, although the output is set to CV-Mode and no load ist attached.All these issues come from dried out and defective caps on the analogue PCB. The defective caps are C316, C317, C366 and C367 (see pictures). They filter the recified AC voltage for the analogue part of the power supply.Funny part:The caps are mounted directly above a heatsink, wich ... sinks quite a bit of heat. So it's kind of an extra fast dry-out by designI replaced all the caps with 105°C versions. (original: 16V 470u 85°C, replacement: 16V 1000uF 105°C)The 1000uF were used, because i didn't have 470uF at hand. But that didn't seem to matter. The protecting glass fuses didn't blow due to the longer lasting load current of the caps by nowGreetings, Burner_357

author: Fraser
author_rank: Super Contributor
timestamp: October 27, 2018, 10:35:40 pm
content: Burner_357,Many thanks for this. My PN300 is currently working well but when I find time I will fit new capacitors as a preventative maintenance jobI bought the service Data for all my Digimess equipment in case of future need. My FG100 20 MHz function generator tripped my house ELCB last time I used it so I will be changing the input EMI filter before I use it again.I was very recently in contact with Tim Coates who is the company director. A very friendly and approachable gentleman who helped me get what I needed. Good support, if a little expensive for service manuals.He supplied me with the PC software for my various Digimess units as £5 per unit. It used to cost £49 per unit !Fraser

author: Fraser
author_rank: Super Contributor
timestamp: November 03, 2018, 08:11:30 pm
content: Looks like the OP no longer needs the schematics ?Digimess were great when dealing with me and my technical support needs. I can recommend their technical support. You are actually dealing with the Director of the company when you ask for help !Fraser

author: amiq
author_rank: Regular Contributor
timestamp: October 26, 2019, 06:50:41 pm
content: Are they in pdf format? What did you have in mind for a copy?

author: Nixfried
author_rank: Contributor
timestamp: December 28, 2019, 01:38:56 pm
content: I'm also interested in this Service Manual, can someone help me out?