Search found 26 matches

by eccles
Wed Feb 26, 2020 9:26 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

So I refitted all lifted/removed components, including a ZTX213 for TR5 and a ZTX650 for TR4 (both brand new and tested before fitting)

9v with 700mA limiter. Triggers overcurrent protection every time

Sad face :-(

I'm entertaining suggestions once more.....
by eccles
Mon Feb 24, 2020 10:29 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

I carefully nailpolished the bare bit of trace and then resoldered the coil. I noticed the construction of the coil is such that part of the winding wire is present on the underside of the coil, such that if pushed down on the board, this part of the winding wire would touch any bare metal on the to...
by eccles
Wed Feb 19, 2020 8:50 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

I may just remove the coil temporarily to see what happens - it's the last major component left that could be shorting to ground before I start pulling the remainder one thing at a time. Edit: Having removed the coil, the short went away. Inspection of the underside now the coil is gone might lend a...
by eccles
Mon Feb 17, 2020 9:26 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

R59 is almost smack on 1.8K
C44 checks out at 100uF 0.9ohm ESR

+12V lead to where the +ve of C44 was
GND lead to -ve of C45

EDIT:
I got confident (not earned, as i'm a novice)

I reconnected R59, and removed R58 and TR5 - short gone
Reconnected R58, short returns (R58 checks out at 1K)
by eccles
Sun Feb 16, 2020 7:18 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

(Reminder TR4 is still out of circuit)

Removed C5-C8 - short remained
Disconnected R59 and C44 - current draw went to zero
Replaced C5-C8, current draw still zero

Suggests to me the issue still lay in the DC-DC converted board somewhere....
by eccles
Fri Feb 14, 2020 9:21 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

Having cocking the leg of R62 (and confirming +12VA was now seperated), I tried injecting as before +ve to +ve of C44 and gnd to -ve of C45 12v at 130mA still tripped the supply Would I be right in thinking that if I were to lift R59 and the -ve lead of C44, this will completely isolate the DC-DC co...
by eccles
Wed Feb 12, 2020 10:18 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

OK, went +ve to positive of C44, and ground to negative of C45 Both at 100mA and 130mA, the current limiter of the bench supply is tripped. So it would appear then I have a short on the 12V line Looking at the schematics, the stuff I ought to be looking at are: IC6-13 (already removed, currently hav...
by eccles
Wed Feb 12, 2020 9:47 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

I've checked all my diodes, and they're good.

Where would you reccommend injecting 12V? Positive side of C44 goes to the +12V DRAM supply, Positive side of C45 goes to +12VA(Analogue supply) (or either side of R62)

Now to try and find some spare banana plugs to make up a jumper cable...
by eccles
Mon Feb 10, 2020 11:26 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

Hi Mark, Haven't had a chance to look into this further, but TR4 shows fine when tested. The bench power supply allows me to set voltage and current limits - is there anywhere you suggest I inject 12v, and should I remove anything first from DC-DC converter stage to avoid issues? The only diode that...
by eccles
Sun Feb 09, 2020 9:11 pm
Forum: Hardware
Topic: Issue 4a docs needed
Replies: 45
Views: 13386

Re: Issue 4a docs needed

I'll hoike out the coil next, then