Fender M-80 chorus problém

[Jazz P Bass]

Lamp Current Limiter

The best that I could do in Paint.

[vintagekiki]

Readme Lamp current limiter

[warry]

Sorry vintagekiki & Jazz P Bass, I am probably very stupid. But I don't understand where I have to put the current limiter.
- from where come from the L1 & L2?
- what is the device under test?

I'm not sur but for me, the L1 & L2 are coming from my power supply (220V/50Hz in france).
And I connect each wire of "device under test" on the fuse support.


No???

[vintagekiki]

Device under test is trouble amp.
Bulb limit excessive current (depending on the power light bulbs) to a value which is not dangerous for the power transformer. Power bulb is 25-30% of the power amplifier.

[Enzo]

Warry, it is simple - we add the bulb in series with the amp mains power. Wire it in the same way you would wire in a fuse.

[J M Fahey]

Warry, s'il vous plaît regardez les suivants images:


Elles sont exactement la męme chose (j'ai pas utilisé le switch)
A gauche de mon dessin vous avez le "socket" (prise de courant femelle?) 220V dans le mur.
A droite vous avez une prise de courant limitée femelle, ou vous branchez le amplificateur.
Vous branchez a gauche la prise de courant mâle du limiteur, a que tien 2 fils.
Un fil est branché directement d'un pôle a gauche a un pôle a droite.
Vous devez couper l'autre fil pour interrompre le pas de courant, e brancher ces deux nouveaux extrémités libres dans

Ça va obliger a courant de traverser a lampe, a que va limiter la puissance que votre amplificateur peut recevoir.
Construisez le vôtre e postez la photo ici.
Merci.
<<<<<<<<<<<<<<<<<<<<<<<
Warry, please look at these pictures.
They both show exactly the same (I didn't use a switch)
On your left, you have the "regular" 220V socket on the wall.
On your right you have e current-limited socket where you plug your amplifier.
You plug on the left socket the limiter plug, which has two wires.
One of them goes straight to one pin of the right socket.
You cut the other and wire a lamp socket joining those two free ends.
Now the current will be forced to go through the lamp, which limits the power your amplifier can receive.
Build it and post a picture here.
Thanks.

[warry]

Hello everybody.

First I'm sorry for my silence. I had a lot of work.

So I mad the current limiter. And I just read the values without the fuse does not burn.

I seen this values:

TP1 = 1.035 VAC
TP2 = 1.020 VAC
TP3 = 0.268 VDC
TP4 = -0.271 VDC
TP5 = 0.254 VDC
TP6 = -0.258 VDC
TP7 = 0.122 VDC
TP8 = -0.124VDC

TP28 = 0.178 VDC
TP29 = -0.176 VDC
TP30 = -0.004 VDC
TP31 = -0.005 VDC
TP32 = 0.186 VDC
TP33 = 0.183 VDC
TP34 = 0.021 VDC
TP35 = 0.024 VDC


If you have an idea, or if you want that I control an other TP, just tell me.

Thank you very much.

[vintagekiki]

Yes fuse does not burn, but you do not ac voltage at TP1 = TP2 alternating current test point (~ 30VAC), and therefore you have no voltage at TP4 (-40VDC) or TP3 (+40 VDC).
Verify proper polarization diode CR50-CR54, and check if you do not accidentally short circuit was created by the tin round diode CR50-CR54.

[warry]

Heuuu excuse me, but before make the current limiter, I had this tensions (+40V / -40v...)
I think the bulb take a part of the 220 VAC.
No?

[J M Fahey]

Yes, at this moment the bulb takes most of 220V because your amp is shorted.
TP1/2 values make me think that the diodes are fine.
What you do not tell us, is whether the bulb shines brightly (I think so) or dim.

[Jazz P Bass]

Lamp Limiter

Sounds to me like the lamp limiter is doing it's job!
You still have a short!
Stop applying power at this point.
With power off, measure the resistance to ground at all test points.
You will find the problem with this procedure.
If you cannot find the problem , I would suggest taking it to a tech.

[vintagekiki]

If there is no short circuit between TP3 or TP4 and ground, if the output transistors Q8 / 9 and Q12/13 removed, and if they are properly connected diode CR50-53 (6A4), voltage in TP1/TP2 must be 30VAC, voltage in TP3/TP4 must be + / - 40 VDC, and the lamp limiter light is very weak.
If a very bright lamp, it is a sign that there is a short circuit, or a defective component in the line TP3/TP4 (+ / - 40 VDC)

[warry]

Yes, I have a very bright lamp, when I switch on the amp with the current limiter.
When I removed the Q8/Q9/Q12/Q13, I haven't problem.
But When I connect the TIPs, the XF3 fuse burn (and sometime, XF2 too)
I measured the resistance to ground at some test points: in time to time, I have an irregular résistance. The values is always changing.

[Enzo]

OK, then most likely both positive and negative side power transistors are turning on at the same time.

There are two powr amps amps in this - only takes one to blow fuses.

In the upper half of the drawing, look just to the right of the IC U12. From top to bottom, there is a string of parts. R127,R128, CR20,CR21,CR22,CR23, R130, R129. Are ANY of those open? DO all four diodes test as diodes?

Now go through the lower power amp checking the corresponding parts.

[warry]

OK, then most likely both positive and negative side power transistors are turning on at the same time.

There are two powr amps amps in this - only takes one to blow fuses.

In the upper half of the drawing, look just to the right of the IC U12. From top to bottom, there is a string of parts. R127,R128, CR20,CR21,CR22,CR23, R130, R129. Are ANY of those open? DO all four diodes test as diodes?

Now go through the lower power amp checking the corresponding parts.

Excuse me Enzo, but I understood nothing. My english is too poor.