Dual La2a - [silent:arts] version

This section is for registered users to discussspecific projects and troubleshooting.

Moderatoren: TVPstudio, kubi

[silent:arts]
Beiträge: 3520
Registriert: Sa Jun 10, 2006 5:54 pm
Wohnort: BLN
Kontaktdaten:

Beitrag von [silent:arts] »

Yes, the heater goes to ground via the 100r (but you used the holes right after the terminal block, before the 100r resistors ?)
or wait, maybe you did not know you have to wire the heaters like in Drips v1 ?

should look something like this, or better (the silicon cable I used is not good drilled together:
Bild

Take the tubes out and measure each heater terminal block input to ground if you actually have 100r. the PCB Billex made for me had a short at one side to ground (I checked the PCB Bernd send me for this, and it was right - but you never know).
[edit: with no power transformer connected of course]

the neon lamp is on the HV rail, if it shines it has more than 65V - that's good.

the best place to measure the HV (High Voltage) is the left side (looking from the front) of R129 or R229.
Zuletzt geändert von [silent:arts] am Fr Feb 11, 2011 8:23 am, insgesamt 3-mal geändert.
volker
olafmatt hat geschrieben:Strom kann tot machen

bernbrue
Beiträge: 1128
Registriert: Do Jun 29, 2006 4:55 pm
Wohnort: Wolfenbüttel

Beitrag von bernbrue »

Hi,
Heater voltage is AC and after a closer look to the solder side of the pcb it seems, that the heaters (H1L, H2L, H1R, H2R) have to be wired by hand. Is that right Volker?
regards
Bernd

bernbrue
Beiträge: 1128
Registriert: Do Jun 29, 2006 4:55 pm
Wohnort: Wolfenbüttel

Beitrag von bernbrue »

Volker, you are too fast :lol:

waldorfcave
Beiträge: 265
Registriert: Sa Jun 03, 2006 6:26 pm
Wohnort: Kölle
Kontaktdaten:

Beitrag von waldorfcave »

damm, sure now erverything is clear :P

[silent:arts]
Beiträge: 3520
Registriert: Sa Jun 10, 2006 5:54 pm
Wohnort: BLN
Kontaktdaten:

Beitrag von [silent:arts] »

:D I hate this undocumented projects :lol:
volker
olafmatt hat geschrieben:Strom kann tot machen

waldorfcave
Beiträge: 265
Registriert: Sa Jun 03, 2006 6:26 pm
Wohnort: Kölle
Kontaktdaten:

Beitrag von waldorfcave »

yes volker you are the man :P

after all my questions this projekt is very well documented :roll:


thx

waldorfcave
Beiträge: 265
Registriert: Sa Jun 03, 2006 6:26 pm
Wohnort: Kölle
Kontaktdaten:

Beitrag von waldorfcave »

ok...this thing is running and compressing. :lol:

gain ratio have to be tuned like volker said (i use sowters) i do it later....

one problem is, that my unit hums a bit. more then it is ok for me :-(

it comes not from the powertransformer, i can move it from side to side and nothing happens.

maybe the ac heaters under the pcb?

i have measured the heater against ground, and i only have around 60 ohms
resistance between ground, but volker said it have to 100R?

maybe this is the fault?

maybe someone has an idea where to look first....

i will try and try :P

[silent:arts]
Beiträge: 3520
Registriert: Sa Jun 10, 2006 5:54 pm
Wohnort: BLN
Kontaktdaten:

Beitrag von [silent:arts] »

mhm, no hum here.
is it on both channels ?
can you do a photo of your ground pattern ?
volker
olafmatt hat geschrieben:Strom kann tot machen

waldorfcave
Beiträge: 265
Registriert: Sa Jun 03, 2006 6:26 pm
Wohnort: Kölle
Kontaktdaten:

Beitrag von waldorfcave »

yes on both channels, exact the same

in the motherforum someone changed the rectifiers , and then his hum disapeares

Bild

waldorfcave
Beiträge: 265
Registriert: Sa Jun 03, 2006 6:26 pm
Wohnort: Kölle
Kontaktdaten:

Beitrag von waldorfcave »

...change the retrifiers still hum

[silent:arts]
Beiträge: 3520
Registriert: Sa Jun 10, 2006 5:54 pm
Wohnort: BLN
Kontaktdaten:

Beitrag von [silent:arts] »

all looks good at the photo.
when you disconnect the heaters from one side, is there still hum on the other side ?
volker
olafmatt hat geschrieben:Strom kann tot machen

[silent:arts]
Beiträge: 3520
Registriert: Sa Jun 10, 2006 5:54 pm
Wohnort: BLN
Kontaktdaten:

Beitrag von [silent:arts] »

waldorfcave hat geschrieben:gain ratio have to be tuned like volker said (i use sowters) i do it later....

one problem is, that my unit hums a bit. more then it is ok for me :-(
how much is "a bit" ? (LA2As are not famous for low noise)
is the hum constant or gain depended ?
volker
olafmatt hat geschrieben:Strom kann tot machen

waldorfcave
Beiträge: 265
Registriert: Sa Jun 03, 2006 6:26 pm
Wohnort: Kölle
Kontaktdaten:

Beitrag von waldorfcave »

hum is to loud, not normal

hum is constant not gain depended.

rewire my ac heaters and check in one minute

Harpo
Beiträge: 463
Registriert: Fr Jun 22, 2007 12:22 am
Wohnort: Rahden NRW

Beitrag von Harpo »

Did you mount the 7805 isolated from heatsink and caseground? Doppelkühlung :) You may have a ground loop. Is hum frequency pre (mains side) or post rectifier (double mains frequency)?

-Harpo
mische lauter - Ohren wachsen nach
Ist mir Scheißegal wer dein Vater ist. Solange ich am Angeln bin, gehst Du hier nicht übers Wasser !

bernbrue
Beiträge: 1128
Registriert: Do Jun 29, 2006 4:55 pm
Wohnort: Wolfenbüttel

Beitrag von bernbrue »

Lars,
did you use shielded wires for pots, output tranny and XLR? The HT wiring is a real pita. :x :) :) :) :)
Never mind, Volker
regards
Bernd

Antworten