jsteiger said:Are you 100% sure the zeners and 914s were not mixed up?
Can you check again the resistance from the DOA output pin to ground? This should be a very low resistance so set your DMM accordingly.saturnjayzero said:Hi all,
I just finished my first of 2 LC25 yesterday but when i put in a DOA (Prebuilt JE-990 by Haibrall) PR5 and PR6 went up in smoke.
PR5&6 connect to the supply voltages of the DOA (+15, -15V) which I measured before. The DOA worked well in a Haibrall Lola and a CAPI VP28 before. Additionally to the burnt resistors the the Output transistors of the DOA got really hot. I also measured that TP4 connects to ground, is that ok (via 2503?)?
I also checked the DOA on it's own ie connected it to a supply where each (+ and -) consumed about 2mAmps. I don't know where to look.
Greetings from Graz
What rack are you using? When we build them and test, they are wide open laying on a bench with a test jig. No enclosure. No noise or hum at all. That is why I am questioning the rack you are using.saturnjayzero said:Sorry Jeff, I got that too. Turns out testing a unit alone in the middle of a 6 slot rack can lead to weird radio interferences. That included the ringing noise and low humming every time my hand entered the inside of the rack.
jsteiger said:What rack are you using? When we build them and test, they are wide open laying on a bench with a test jig. No enclosure. No noise or hum at all. That is why I am questioning the rack you are using.
jsteiger said:Yes that's possible but not sure its something I would have the time for. There are 2 resistor ladders for cut/boost. Each has 5 switches. You would need to rework those R's All on the switch PCB that the Grayhill's mount to. My screen shop is not really conducive to small runs or custom orders. They do fabulous work but it would cost $380 for new films and then a minimum dollar amount per run. They only make sense for large runs.
Yes send me an email. I prepared this info for a guy before but once he realized what was actually involved he never followed thru with the build.Blackdawg said:Gotcha.
Well I could always attempt my own panel which sounds like a terrible idea..haha
Is it possible to get the schematic of the ladder at least to wrap my head around it to help figure out what I'd need to make that happen? I can of course shoot you an email about this if that would be better.
jsteiger said:Yes send me an email. I prepared this info for a guy before but once he realized what was actually involved he never followed thru with the build.
LED direction as well as the 1N914s on the switch PCB.saturnjayzero said:Hey Jeff,
I finally got around building my second one. It sounds and works really great with one caveat: The status LEDs don't work/ Do you have any ideas what to check (beside Diode direction)?
Have a nice weekend
jsteiger said:LED direction as well as the 1N914s on the switch PCB.
The 5kHz gyrator is comprised of GR21, GR22, GR24, GC15 and GC16. Also half of A4 which is shared with 2.5kHz. If that is fine I would ASSume the chip is fine.Thekahn said:Hi Jeff,
Thought everything was good on my LC40 build, but upon closer examination, the 5khz knob only moves in maybe .5 dB increments. I checked using a plugin called “plugin doctor” to check the curves of everything. Any areas specifically I should check for cold solder joints etc? Thanks in advance,