Hello,
My Pioneer TX-608 tuner has strange manners.
I can keep turning at the ‘tuner’ wheel untill tomorrow, nothing happens.
It seems as he has no reception at all.
The signal indicator doesn’t move, also the fine tuning meter doesn’t move, whatever I do. There is power on the unit.
My radio knowledge is not so fantastic. Last time I was really helped alot by the community here, so I wonder if there’s anyone who can help me find the problem?
Thank you in advance,
Vintagelover
Pioneer TX-608 AM/FM Stereo Tuner Manual | HiFi Engine
My Pioneer TX-608 tuner has strange manners.
I can keep turning at the ‘tuner’ wheel untill tomorrow, nothing happens.
It seems as he has no reception at all.
The signal indicator doesn’t move, also the fine tuning meter doesn’t move, whatever I do. There is power on the unit.
My radio knowledge is not so fantastic. Last time I was really helped alot by the community here, so I wonder if there’s anyone who can help me find the problem?
Thank you in advance,
Vintagelover
Pioneer TX-608 AM/FM Stereo Tuner Manual | HiFi Engine
Hi Vintagelover,
That's a standard tuner, nothing special about how it works.
Your tuning string is broken or loose. That's why your pointer doesn't move. Pop the top off and observe the string where it connects to the pointer. Is it a little loose, or no tension at all? The other thing that can happen is the pulley for the tuning cap can come out due to a worn bearing. So have a look at the pulley for the tuning capacitor. Take a picture please.
-Chris
That's a standard tuner, nothing special about how it works.
Your tuning string is broken or loose. That's why your pointer doesn't move. Pop the top off and observe the string where it connects to the pointer. Is it a little loose, or no tension at all? The other thing that can happen is the pulley for the tuning cap can come out due to a worn bearing. So have a look at the pulley for the tuning capacitor. Take a picture please.
-Chris
No it’s not the tuning string. I have checked this already. The tuning pointer moves, as well the tuning capacitor. Everything is normal. It’s the fine tuning needle that doesn’t move, the one who helps to find the exactly good point when you’re close to a radio station.
Yup, the 12 VDC supply is the next common failure point. Pioneer tends to run regulators hot.
-Chris
-Chris
Can you be more specific?
Q12 I have the following measurements:
Base 4V instead of 14V
Emitter 3,4V instead of 13,4V
Collector 20V instead of 16,2V
Q12 I have the following measurements:
Base 4V instead of 14V
Emitter 3,4V instead of 13,4V
Collector 20V instead of 16,2V
Both diodes are running with high load (for lack of a better word now).
But if you see full input voltage on Coll. of Q 12 check C85 (330/25).
If not then D12, C86.
But if you see full input voltage on Coll. of Q 12 check C85 (330/25).
If not then D12, C86.
Hit my quota at HiFiEngine. My schematic download was only a partial too. I should have downloaded the thing when I looked at it earlier.
Your collector is high due to lack of load. Looks like the pass transistor went open C-E and the current is trying to come through the E-B connection. No surprise, seen it before. Replace the pass transistor - Q12. It's rated for 3A if memory serves, so a TIP41 would work fine.
Your collector is high due to lack of load. Looks like the pass transistor went open C-E and the current is trying to come through the E-B connection. No surprise, seen it before. Replace the pass transistor - Q12. It's rated for 3A if memory serves, so a TIP41 would work fine.
Hi Yes,
The collector voltage is high, 20 VDC instead of 16 VDC. So, no load to speak of. The emitter-base connection is fine however.
That transistor has gone open collector- emitter. It's not the first time I have seen this. Replace the open pass transistor.
-Chris
The collector voltage is high, 20 VDC instead of 16 VDC. So, no load to speak of. The emitter-base connection is fine however.
That transistor has gone open collector- emitter. It's not the first time I have seen this. Replace the open pass transistor.
-Chris
D10 was a wrong thought 😉
Alright, I’ll replace Q12 and let you guys know.
Thank you in advance!
Alright, I’ll replace Q12 and let you guys know.
Thank you in advance!
Hi Vintagelover,
Expect Q12 to run very warm. Don't be alarmed.
If you are going to keep it, figure out how to enlarge the area of the heat sink. Sometimes you can add a smaller one and use some heat sink grease. That will lower the temperature of the regulator. It will last longer.
-Chris
Expect Q12 to run very warm. Don't be alarmed.
If you are going to keep it, figure out how to enlarge the area of the heat sink. Sometimes you can add a smaller one and use some heat sink grease. That will lower the temperature of the regulator. It will last longer.
-Chris