Sigh.. Dim Bulb Test Failure
- Thread starter 147JK
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petehall347
the brandy coffee man
bloody hell ..and voltage was checked earlier at r606 ..i would have expected higher mv.s on the cap side if the cap was leaky .. not 0v . i have been having thoughts there might be a lot of ac on the circuit from the rectifier diodes and c601 not smoothing it .. there was a loud hum earlier after the first time tr602 was removed ..
just looked back and i was saying c603 might be leaky a few times ..first time was post 131..
just looked back and i was saying c603 might be leaky a few times ..first time was post 131..
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Diodes are on order - will be a few days. In the meantime I will try replacing c603.
petehall347
the brandy coffee man
am waiting with bated breath ...
This what is known as discriminating tasteful pause...
Is the expression 'awaiting with ("Bated Breath?") the U.K. version of "baited breath"? or I suppose if you had a habit of eating bait while fishing "bait breath" could be used.
A quote from "world wide words"
"Bated and baited sound the same and we no longer use bated (let alone the verb to bate), outside this one set phrase, which has become an idiom. Confusion is almost inevitable. Bated here is a contraction of abated through loss of the unstressed first vowel (a process called aphesis); it means “reduced, lessened, lowered in force”. So bated breath refers to a state in which you almost stop breathing as a result of some strong emotion, such as terror or awe."
Also waiting in anticipation of the OP's next post.....
petehall347
the brandy coffee man
i don't care on the spelling ...
my breath is more bated than its ever been .
my breath is more bated than its ever been .
No luck (yet)
Well darn it, I..
Replaced C603. Fired it up. No change, still flashing protection light.
Replaced all diodes with new. Fired it up. No change, still flashing protection light.
So then I backed up and pulled r606 again. With that resistor pulled, it will come out of protection, but after a few minutes it starts humming and I think the main fuse will blow again if left running like that. Anyway while it was running, I re-checked and set the offset and bias on both channels - no problems. Then I hooked up a tuner and some speakers. Turns out the left channel puts out sound, but there is nothing coming from the right channel.
I still wonder if the problem is actually out on the right channel driver board..??
Well darn it, I..
Replaced C603. Fired it up. No change, still flashing protection light.
Replaced all diodes with new. Fired it up. No change, still flashing protection light.
So then I backed up and pulled r606 again. With that resistor pulled, it will come out of protection, but after a few minutes it starts humming and I think the main fuse will blow again if left running like that. Anyway while it was running, I re-checked and set the offset and bias on both channels - no problems. Then I hooked up a tuner and some speakers. Turns out the left channel puts out sound, but there is nothing coming from the right channel.
I still wonder if the problem is actually out on the right channel driver board..??
Out of protection by pulling up r606. Like that it puts out sound in the left channel only.
petehall347
the brandy coffee man
do you have replacements for d601 d602 ? if so change them as it might be the cause of the problem .(AC leaking past them) it would rule it out anyway
also check c603 for orientation and continuity ..negative to ground . positive to r601 .
it wouldn't really explain loss of a channel though ..that looks like a separate issue as we disconnected stuff earlier so the protection should have clicked in regardless .
did you check the power supply board after the sparks ? if not it might be a good idea to check it over .
also check c603 for orientation and continuity ..negative to ground . positive to r601 .
it wouldn't really explain loss of a channel though ..that looks like a separate issue as we disconnected stuff earlier so the protection should have clicked in regardless .
did you check the power supply board after the sparks ? if not it might be a good idea to check it over .
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I don't have the zener diodes for d601 or d602. I can pick some up though.
c603 is a film capacitor.. I don't think polarity would be an issue..??
I started looking at F-2722, right-channel driver board. In checking TR702, I was seeing readings very different than those on the left board. Started poking around and have found R44 is open! Will replace R44 see what happens.
petehall347
the brandy coffee man
i wasn't referring to the zeners . ZD601 ZD602 i was referring to D601 D602 they are rectifier diodes .
Yes I did lift a leg of diodes D601 and D602 a while back. They appeared to check out OK.
I replaced R44. No change - still in protection.:tears:
However here is one finding.. I am not getting any voltage reading at all at the bias test point for the right channel (F-2722). I do get a good reading at that point on the left channel (F-2721). So I went down all the pins on each driver board and compared left vs right. The reading for each pin on the left board is the same as the corresponding one for the right. This is the case for every pin plugged into the protection circuit.
This would indicate the problem is somewhere on the right channel driver board, yes?
petehall347
the brandy coffee man
if the board is getting the correct voltages then yes there is a problem on the board .. it isn't keeping it out of protect though .
if its possible for you print out the schematic and take voltage readings from your board and mark them onto the print out then upload the results so we can try and see what's going on with it .
if its possible for you print out the schematic and take voltage readings from your board and mark them onto the print out then upload the results so we can try and see what's going on with it .
petehall347
the brandy coffee man
any joy with it yet ?
