Barry Porter "Net EQ"

[Gustav]

You can place the last resistor on the chain into the short positions save having them hanging off the rotary.

No need - theres an extra lug on the switches Im using

Gustav

 

[Gustav]

Single pole is all that's required. The extra pole would be there to add rigidity if mounted to the board.

Thanks!

Gustav

 

[alexg]

No, that EQ below the BP is built using Igor's GML/Massenburg 'MEP250' boards with MS/Bypass, before the DR-MQ5 copies came out.

Interesting to see those two in the same studio.
Could you tell us their sonic differences & character?
Thanks !

 

[Gustav]

Im afraid to finish this.

Gustav

 

[yourdudeness]

Hello, any recomendations for L1?

 

[Gustav]

Voltages seem good.

Thanks for all the help, boys!

Gustav

 

[Gustav]

Hello, any recomendations for L1?

Jump it..

 

[petermontg]

I am still having trouble with mine. Problem is on both boards voltage seems to get lost after the regulator 12V. The opamps are reading fine. In C26/27 I have 2 100V Caps where should be 25V.  Would this be causing my problem, I am not sure it is. I am reading V for the relay afterwards.

I unplug PSU to double check still checks out fine when plug it back in voltage slowly rise/increases when checked what the PSU is doing when plugged to boards and no voltages across previous checks

This has lead me to think that there is something amiss in C19/20/21/22.

Anybody want to add some insight to get my brain thinking in the right direction. I could have hit the nail on the head already?

 

[Harpo]

In C26/27 I have 2 100V Caps where should be 25V.  Would this be causing my problem, I am not sure it is.

You probably refer to C21/C22 (100uF/25V), not C26/C27 (100nF caps).  No problem, as long as caps voltage rating is higher than voltage across these caps (>18V in front of 7812 and >12V after 7812). Higher voltage rated caps most often come with increased outer dimensions.

I am reading V for the relay afterwards.

missing value for your V reading, probably something in range from nada up to +12VDC.

I unplug PSU to double check still checks out fine when plug it back in voltage slowly rise/increases when checked what the PSU is doing when plugged to boards and no voltages across previous checks

This has lead me to think that there is something amiss in C19/20/21/22.

Anybody want to add some insight to get my brain thinking in the right direction. I could have hit the nail on the head already?

Maybe double check polarity of C19, C20, C21, C22, orientation of diodes D1, D2, D3, D4 and transistors are BC182 for real (not different pinout BC182L).

 

[petermontg]

Thanks harpo, all polarity and rotation is correct checked and double checked.  BC182 transistors, I have the B in there as I was aware of jeffs problem with L series.  I will try with the BC182 thanks harpo

 

[Harpo]

I will try with the BC182

Not needed (unless your BC182Bs are broken). Problem will be in a different spot then. (Relais ?, additional LEDs with maybe missing/wrong current limiting resistors ?, insufficient current delivery from preceding +18VDC stage ?, ...)

 

[petermontg]

My current from psu is 1.5ma. Problem is still present when disconnected from switches and leds. I had calculated the limiting resistor. Going to desolder relays and transistors and check. I have Continuity across a couple of the PF and NF caps in the same places on both boards I am thinking maybe below what my MM could read?? but maybe if that was the case they all should read Continuity. Am I wrong in thinking this?

 

[Harpo]

I have Continuity across a couple of the PF and NF caps in the same places on both boards...

Continuity test AKA beeper mode ? Only maybe useful for sorting unlabled multicore wires or hooking up a caravan, but not much use in electronics. Use your multimeters ohm setting in order to get a meaningful number. A short will give a zero or close to zero ohm readout (pcb traces and/or your measuring leads have a resistance as well). You never said what psu you are using, whats the data of the mains transformer in front or whatever circuit variations or add ons you have implemented.

 

[frazzman]

Hey all,

I finally got a chance to power up one of my Net EQ channels... for the 'smoke test', unfortunately it failed that test. At the moment all I have connected to the PCB is the bypass LED and switch, hoping to have seen a gleaming red LED looking back at me...

R1, R18 and R19 get extremely hot very quickly and start smoking after about 20 secs. I used 3W resistors in these locations.

I'm using the calrec PSU with a 2x18V toroid. I built up and tested the PSU first, I'm getting sturdy. + 18V rails so I believe the PSU board is working correctly. I also noticed the regulators seemed to heat up very quickly as well. 

I've checked the obvious things like shorts in this area and that I didn't get the neg and pos leads switched around... appreciate any other ideas...

 

[frazzman]

Just wired up my second channel.... Exact same issue. R1 feels like a hot plate within about 10 seconds. I'm guessing I made a fundamental error with some component selection or was unfortunate enough to induce the same error on both boards

 

[petermontg]

Thanks harpo. I have a generic PS I got on evilbay based on 337/317, tordial is 230/18v I have no mods or attached circuit. Am going to go through the whoIe thing again. I had power to the bypass led when I wriggled the ps leads to the board when I disconnected to check and reconnected, it popped  the 10r metal oxide on the minus line. I checked for coId soIder and found none.  Do you think I shouId be chasing the probIem in the ps??

I  have the same problem as you frazzman they pop, as paul says they are acting as fuses.

 

[druu]

frazzman: I had that issue too remember! Turned out to be the +/-18v I had reversed.

 

[druu]

I'm still convinced the schem pinout is wrong for the PSU input wires..

 

[Harpo]

I'm still convinced the schem pinout is wrong for the PSU input wires..

Maybe only your assumption is wrong that the 10-pin connectors are populated with same orientation, IE pin1 of CON1 and CON2 are both the leftmost pin ... 
(pin1 of CON2 (the +18VDC connection) is the rightmost pin)

 

[Gustav]

I'm still convinced the schem pinout is wrong for the PSU input wires..

The pinout is correct on the schem, and pin 1 is marked with a square on the board for both com1 and com2.

They are not oriented identically, though.

Gustav