Hi guys,
I've encountered an odd problem with this Deviton 4080 receiver I've pickup up. First of all, it's an obscure German rebranding of an already obscure Project/One mark IVB receiver. (It says Mark IVB on the transformer and meters.)
So I haven't been able to find any schematics or service manual.
After replacing the relay, fixing the meters, adjusting bias (by feel, per another thread here) and cleaning the pots the unit plays great. Good sound, lots of power.
However, the FM stereo doesn't work, and when I press the FM muting button, all sound cuts out. The reception in FM mono is great, it's picking up more stations than my main receiver.
When I activate FM muting, my tuning and signal strength meters still move about, but I get no sound. So maybe it's muting too 'strictly'?
Turning the pots on the fm board didn't help. (I'm still not sure which one is the stereo pot, but I've marked then tried all of them and put them back in their original state.)
I've been reading some threads here from other receivers with similar issues, and I thought maybe the HA1137W IC is at fault, since it controls muting.
Otherwise I think the tuner might need aligning.
Since I don't have the knowhow or tools to do that, I went ahead and replaced the HA1137W. Nothing about the muting/FM stereo issue changed, but I did get a little bit better reception still.
Now I'm thinking there might me some other component after the HA1137W at fault, but without a schematic, I'm kinda at a loss.
Has anyone here encountered a similar problem?
I took some measurements of the HA1137W:
Muting off:
(pin) 1: 1.98V
2: 1.98V
3: 1.98V
6: 5.76V
7: 5.73V
10: 5.53V
12: 6.42V
Muting on:
1: 1.98V
2: 1.98V
3: 1.98V
6: 5.58V
7: 5.73V
10: 5.54V
12: 3.56V
Any help is appreciated!
(Pic attached is of the radio board)
PS: I got 10x HA1137W for €5 and they're legit, I've 9 left so if anyone needs one of let me know.
I've encountered an odd problem with this Deviton 4080 receiver I've pickup up. First of all, it's an obscure German rebranding of an already obscure Project/One mark IVB receiver. (It says Mark IVB on the transformer and meters.)
So I haven't been able to find any schematics or service manual.
After replacing the relay, fixing the meters, adjusting bias (by feel, per another thread here) and cleaning the pots the unit plays great. Good sound, lots of power.
However, the FM stereo doesn't work, and when I press the FM muting button, all sound cuts out. The reception in FM mono is great, it's picking up more stations than my main receiver.
When I activate FM muting, my tuning and signal strength meters still move about, but I get no sound. So maybe it's muting too 'strictly'?
Turning the pots on the fm board didn't help. (I'm still not sure which one is the stereo pot, but I've marked then tried all of them and put them back in their original state.)
I've been reading some threads here from other receivers with similar issues, and I thought maybe the HA1137W IC is at fault, since it controls muting.
Otherwise I think the tuner might need aligning.
Since I don't have the knowhow or tools to do that, I went ahead and replaced the HA1137W. Nothing about the muting/FM stereo issue changed, but I did get a little bit better reception still.
Now I'm thinking there might me some other component after the HA1137W at fault, but without a schematic, I'm kinda at a loss.
Has anyone here encountered a similar problem?
I took some measurements of the HA1137W:
Muting off:
(pin) 1: 1.98V
2: 1.98V
3: 1.98V
6: 5.76V
7: 5.73V
10: 5.53V
12: 6.42V
Muting on:
1: 1.98V
2: 1.98V
3: 1.98V
6: 5.58V
7: 5.73V
10: 5.54V
12: 3.56V
Any help is appreciated!
(Pic attached is of the radio board)
PS: I got 10x HA1137W for €5 and they're legit, I've 9 left so if anyone needs one of let me know.
