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Lee My plan now is to moderately restore one of these for selling. By moderate I mean Upgrade PS caps Replace electrolytics on control board C6 value change and diode addition Q1,Q2, Q3 and Q4 replacement Bridge upgrade with WO snubber kit New MJ21196 outputs WO LED upgrade board Don's DCP...

Ok I just fired it up with some power. DBT in the line. Bright then dimmed so ok. Tested rail voltage it was 67.4 on both positive and negative. Checked DC offset and still had rail voltage on left channel. Right side is 4.5mv. Then checked bias Left channel was 388mv and didn't change with...

Ok just had another look at it, for info left channel is putting out DC. Left channel Q8 marked 2n1304 Q9 marked 2n1305 Right channel Q8 marked 2n1308 Q9 marked 2n1307 Does this sound right? Also there is a resistor in parallel to d8 on both channels Left is 3.8k and right is 1.5k. Right...

Gene you are correct re the balanced inputs however both units have that yet only one has the extra circuit board and the other has nothing else but the input plugs. I was wondering if the circuit could have anything to do with the issue the amp has with DC

I didn't get around to powering up for testing but I did open up the unit with DC in one channel and it has some extra bits inside I have not seen before. Does anyone have any ideas what it is?

Joe I'll send you an email

Gene thanks again I'll test shortly. I have these on my dmm to limit shorting out bits hopefully.

Would it have anything to do with an upgraded chassis Joe?

Just opened up the the working unit. Looks like things got a little hot in there at some point! Apart from the obvious is there anything else looking abnormal at the moment? Gotta try and remember how to check bias now......

Ok visual check on fuse condition is good there does seem to be something strange though. All fuses in both amps are 32mm long, my understanding was that AGX fuses are 25mm long. Your thoughts? Also I have never tested them with a dmm before, am guessing use diode or continuity setting? Also...

No blown fuses however I will check them again with the dmm when I get home from work. Probably check the transistors whilst I'm there. Also are some transformers better than others and if so how do I test them? (I might as well white oak the good one)

Wow, awesome setup man! How are you using the three 400s in that setup?

We agree again Gene. My thoughts on the balanced inputs is how can I cover the large holes drilled for the sockets? Parts enroute from Joe are as follows: 3 X warm white light bar kits. 2 X PS cap upgrade kits 1 X control board kit 1 X backplane kit. Currently awaiting an invoice from Don for...

Gene Thanks for that reminder. Here's a couple of things I wasn't expecting. 1. Balanced inputs on both units..... Dunno how I can make that look good 2. My 4 finner didn't have this PCB anywhere so I guess I'm asking is it a Oz add on?

Gene I totally agree with you re the outputs however I have only just got the units so powered them up to get a benchmark. The unit with the faulty channel is throwing 65v DC at the left output. Where should I start looking for the source of this?

The working unit apparently! Now for a quick clean then bring them up for testing

The unit apparently outputting DC in left channel

Just got them home. Not in quite as good physical condition as the photos led me to believe.(I should know better by now) Rare as hens teeth here in Oz ..... Am in way too deep now to back out Prepare yourselves for the incoming pics and questions!

Gene Here's one I prepared earlier for my 4 finner. Agreed that it doesn't look nice but it works and works safely. I am awaiting delivery on the latest 2 400s in the next few hours so be prepared for an onslaught of pics soon!

Mlucitt that's what I'm worried about Still waiting on delivery of the amps so am trying to do some proactive thinking now. As I have limited knowledge/experience with electronics I was considering fixing the broken unit first to learn about fault finding and brush up my soldering skills...