Hello surec,

If you speak English, that is a better basis than the machine translation into German. If you don't speak English even a machine translation into English is likely to help us to communicate. I am afraid, machine translation into German is so lousy that we get a problem to understand each other.

Could you do us a favour and post your problem again here in English?

Thanks and Best Regards,
Reinhard

Hello surec,

Thanks for the English post.

There is no "supply controller". And there is also not any part with that number in that amplituner. And there is also no part that would cost in the order of 80 €.

In a first step you measure the DC voltages against chassis ground.
On the backside (solder side) of the mainboard please locate the measuring points (white printing of numbers in a circle) at the solder side of the power supply connector.

H4 (pin 1 of the power supply connector) should be at 46V
H5 (pin 2 of the power supply connector) should be at 15V
K1 (solder point of bridge rectifier) at 13V
J1 (pin 5 of the power supply connector) at 20V


Then you measure voltages at the solder pins of the left and right power amplifier boards. There are on each power amplifier board seven colored cables soldered in a row:

yellow: +32V
white/yellow: 1,3V
white/green: 0,7V
green: less than 50 mV
grey: 0,65V
white: 0V (ground)
blue: -32V

Please report the voltages you measued. Then we will see.

regards
Reinhard

Hi surec,

Your measured voltages prove that there is no problem with the powersupply or any "supply controller". Voltages from power supply are all perfectly OK.

However, -1,6V DC measured at the green cable of the power stage is not right! This is the line from power-transistor output to the speaker relais and speaker terminals as well as feedback to the difference amplifier stage on the driver module. Actually the protection circuit should sense that there is DC on that output line and shall prevent the speaker relais from closing. Your speakers and headphones should be cut off if there is any DC (positive or negative) on the green cables of the power modules.

1. You are absolutely sure, that you do have -1,6V on the green cables from both power modules?

2. How far do you need to turn the volume knob to the right to hear sound in the speakers at normal room listening volume, to more than 9 o'clock? If you need to turn the volume knob quite far to the right before you hear sound (i.e. from a FM station), we could assume that you only hear crosstalk (from inside relais) of distorted signal but at open relais contacts. Then we must be suspicious that either your driver modules and/or power stages are defective.

For confirmation, proceed this way:
With your speakers plugged off, do you also measure -1,6V DC at the measuring points L1 and L3 at the soldering side of the main board? L1 and L3 measuring points are at the left and right channels outputs respectively, from the relais module to the speaker terminals located at the relais module connector of the main board. Actually, if the relais remains open because the protection circuit senses -1,6V from the green cable, you should not be able to measure the -1,6V at the points L1 and L3. That would prove that your protection circuit and relais work correctly and you have defective driver modules and/or power amp modules.

Please perform these tests first, before we continue here.

9141tc green cable connection_.jpg

Best regards,
Reinhard

Hi surec,

It is not a problem of your multimeter. If the green cables (or L1 and L3 respectively) measure about -3 mV to +3 mV, it is fine! The Voltage is in the right range, depends a bit on the temperature and can vary within this range.

After all, there is no faulty supply voltage. All voltages are within expected ranges.

Did you make sure that the speaker switch is in the correct position (for the speker terminals to which you connected your speakers?
Did you try the other speaker terminals at the Saba with the speaker switch in the right position?

Modules from the 9240 which look the same as in the 9141 can be swapped for testing. You may want to swap the speaker relais module (close to the left corner at the back) with the one from your 9240. Then also the drivers modules (make sure you don't mix up the ones for left and right channel) and linear amplifier modules.

Best Regards,
Reinhard

Hi surec,

Yes, that's right. I can confirm:

Relais Module: 7501107300. It is the same in 9240, 9240S, 9241 and 9141 receivers.
Driver Module: 7501109500. It is the same in 9240,9240S, 9241 and 9141 receivers.

Best regards,
Reinhard

Hi surec,

Nevertheless, if the modules have the same part no., they can be swapped. According to the service manuals, they have the same part no.

Regards,
Reinhard

Hi surec,

Here the excerpts from the service manuals of the 9141 and the 9240, 9240S and 9241.

As your photos also show, the only difference in the relais module is the flyback diode D684 in the 9141. The flyback diode can be added in the 9240, 9240S and 9241 and the relais module functions perfectly with it. A flyback diode changes the timing of the relais a little bit. Probably for that reason, the relais in the 9141 has a slightly different characteristic (i.e. different inductance), that may explain the other relais part no.

Nevertheless, you can swap both relais modules without any risk of harming the units.



The only difference in your driver module of the 9141 and the driver module in the 9240 ist the missing resistor R1131 in your 9241. However, the schematics in my service manuals show R1131 in both cases. Therefore, you can swap the modules. Probably, the power stage offset will be affected which is adjustable with P1103. But for testing your 9141 malfunction it is OK.

Treiber 9141.jpg

Best Regards,
Reinhard

Happy New Year, surec!

What can be investigated next:

Are there any broken solder joints on the main Board (check very closely using a magnification glass)?

The Speaker Switch may have corroded (heavily oxidized) contacts. Can be treated with "Kontakt 61" (blue) (do not use "Kontakt 60" (red)). Spray onto the Switch contacts and then operate the switch often. Oxide layer or sulfide layer on the contakt can cause your problem.

Swap also the power amplifier modules with the ones from the 9240 receiver. If the problem still persists, the root cause is in the Präsenz Module or volume (Lautstärke) module or tone (Klang) module or NF-Filter module or in one of the coupling capacitors in the signal path on the main board.

I have equipment available to feed in a "clean" (distortion free) sinus into the Tape input and then follow systematically through the modules where signal loss or distortion (checked with Oscilloscope) happens. In that way I would locate the bad part. If you do not have that possibility, you can only check by trial and error. I recommend in that case to replace all electrolytic capacitors (particularly also the Tantalum capacitors) in the signal path of both channels on the volume board, the tone board, the Präsenz-board and NF-Filter board.

C2087 and C2088 as well as C2112 and C2113 on the main board are also in the signal path and shall be replaced (always replace with NEW capacitors). Pay attention to put all new capacitors with right polarity!

Are the ICs 2063 and 2083 (electronic switches) socketed? If yes, swap them. Any bad contact would be fixed by that. These switch the signal.

Best regards,
Reinhard

You know, red Kontakt 60 will within a couple of years destroy the contacts, because it makes severe corrosion. You must now wash out all traces of red Kontakt 60 with WL (or plenty of iso-propanol.

Regards,
Reinhard

The power amplifier modules are those two (one per channel) which are directly attached to the large heat sink at the receiver's back (where the 4 power transistors are mounted on the back heat sink for the left and four for the right channel). They are attached with screws from the back. But you are right, you do not need to remove the modules from the receivers. It is sufficient if you unsolder (disconnect) the connecting cables from the soldering pins at these modules and connect them in the same order with to the test receiver by using extensions. But make sure that you do only keep one (only one!) cable attached per soldering pin (do not connect simultaneously to the test receiver and to the mother receiver).

I highly recommend to take a photo from all the modules prior to unsoldering so that you can later check that you have re-connected the cables correctly.

Because the DC-offset and bias dont match correctly, with the "foreign" driver stages, just check quickly, if you can hear a distortion-free, normal audio signal. Don't test at full power or for longer time in order not to stress the power transistors too much.

Best regards,
Reinhard