Can you meaure again between CP11 and CP12, 1000V AC scale.
Not DC and Not referenced to ground.
Just the two measuring pins to CP11 and CP12.
The amp is in standby.
I like to know the secundary Voltage from the High voltage winding under No Load.
I assume it's ok as you had "Without tubes: C31 +458V" in post 25
Your Heater wiring seems also ok although a bit low.
5.8V instead of 6.3V AC.
This is not enough to explain the bigger drop you have on the +B.
The hum you here, when you connect your testpin to pin 5 of the powertubes, is an indication that your powerstage is working.
The relationship between the voltages on V4 and V5 are ok.
Again, to low.
I think I will receive a HotRod DeVille later this week for repair.
I'll check the voltages there.
Have you tried to plug-in a guitar and play some.
How dos it sound?
Distorted, Low in volume...
Not DC and Not referenced to ground.
Just the two measuring pins to CP11 and CP12.
The amp is in standby.
I like to know the secundary Voltage from the High voltage winding under No Load.
I assume it's ok as you had "Without tubes: C31 +458V" in post 25
Your Heater wiring seems also ok although a bit low.
5.8V instead of 6.3V AC.
This is not enough to explain the bigger drop you have on the +B.
The hum you here, when you connect your testpin to pin 5 of the powertubes, is an indication that your powerstage is working.
The relationship between the voltages on V4 and V5 are ok.
Again, to low.
I think I will receive a HotRod DeVille later this week for repair.
I'll check the voltages there.
Have you tried to plug-in a guitar and play some.
How dos it sound?
Distorted, Low in volume...
Tarzan I placed the meter at 1000acv and placed the positive on CP11 and negative on CP12 and the voltage was 366. I did plug in a guitar but no sound just hum.
OP,
would you be kind enough to post a very LARGE pic of the board? Both with your numbers on them and one w/o.
Also, would you post a current pic of where you are right now? Please make sure these are large enough to zoom into various points in the circuit.
Thanks,
Right amp, wrong scematic & layout,
there should be a newer REV B floating about, 2009?
There should be a recent one posted somewhere.
Ya gotta be careful modding an amp from and old
schematic/layout and brining it forward to a newer model.
would you be kind enough to post a very LARGE pic of the board? Both with your numbers on them and one w/o.
Also, would you post a current pic of where you are right now? Please make sure these are large enough to zoom into various points in the circuit.
Thanks,
Right amp, wrong scematic & layout,
there should be a newer REV B floating about, 2009?
There should be a recent one posted somewhere.
Ya gotta be careful modding an amp from and old
schematic/layout and brining it forward to a newer model.
Last edited:
Ya gotta be careful modding an amp from and old
schematic/layout and bringing it forward to a newer model.
Go to kinkos and get them printed on card stock
and 11 x 17 inch size. You'll have to explain
to the kinko staff the proper way to print them
out as they default to some process that ends
up being really fuzzy and in the incorrect format.
Good luck with your trouble shooting.
We've all been there, done that
at some time or other...welcome to electronics. ; )
I like that so much I'm sticking it in my sig.
update, it won't fit.
schematic/layout and bringing it forward to a newer model.
Go to kinkos and get them printed on card stock
and 11 x 17 inch size. You'll have to explain
to the kinko staff the proper way to print them
out as they default to some process that ends
up being really fuzzy and in the incorrect format.
Good luck with your trouble shooting.
We've all been there, done that
at some time or other...welcome to electronics. ; )
I like that so much I'm sticking it in my sig.
update, it won't fit.
Last edited:
Hm, 366V ac that should give, with no tubes in it around 515VDC.
That's more then enough.
This rules out in 99.99% of the cases that your transformer is bad.
The tubes seems ok.
The output transformer is not shorted.
The power supply caps and dropdown resistors are ok.
So, the rectification can still pose a problem.
Let's check that now.
I would take a look at the diodes CR6, 7, 8 and 9.
Disconnect cp11 and place the amp on stand-by.
Measure the diodes with your multimeter in the Diode position.
Test all 4 diodes in the same way.
That's the positive pin on the anode and the negative pin on the cathode.
Measure again buth now reverse the testleads.
In one position you should measure infinity and the other about 680 to 750.
The one that fails, and I suspect one will read infinity on both sides, will be bad.
It could be that the solderjoint on the board is broken.
You're allmost there.
A bit more patience...
That's more then enough.
This rules out in 99.99% of the cases that your transformer is bad.
The tubes seems ok.
The output transformer is not shorted.
The power supply caps and dropdown resistors are ok.
So, the rectification can still pose a problem.
Let's check that now.
I would take a look at the diodes CR6, 7, 8 and 9.
Disconnect cp11 and place the amp on stand-by.
Measure the diodes with your multimeter in the Diode position.
Test all 4 diodes in the same way.
That's the positive pin on the anode and the negative pin on the cathode.
Measure again buth now reverse the testleads.
In one position you should measure infinity and the other about 680 to 750.
The one that fails, and I suspect one will read infinity on both sides, will be bad.
It could be that the solderjoint on the board is broken.
You're allmost there.
A bit more patience...
Thanks, I have patience that is why I waited a few days. I checked and this is what it listed:
C6: 601/-
C7: 610/-
C8: 601/-
C9: 597/-
These are way below the values you anticipated.
C6: 601/-
C7: 610/-
C8: 601/-
C9: 597/-
These are way below the values you anticipated.
Hello Spacerust,
We have checked allmost everything now and all seems ok.
You hear a loud hum when you measure at pin 5 of V4 and V5.
The dc values of the preamp tubes are also reasonable ok.
Plugging in a guitar dosn't produce any sound; only hum.
I'm thinking in a problem with either the input jack or the Power amp in jack.
These are notorious for their reliablity.
Maybe the solderjoints have been damaged with removing and inserting the pcb into the chassis.
A possibility is also the flatcables that go from the main pcb to the pcb with the tubes on.
1. Check (without any voltage applied!!!) if some wires are not broken on either side.
2. If that all is ok, plug your guitar in to the poweramp input jack and see if you hear any sound.
If yes; the power stage is ok.
If no; have a look at the jack (J4) for bad solderjoints.
3. If yes, Plug your guitar into the input jack and connect, if possible, the preamp out to another amp.
Do you hear any sound?
4. If yes, Connect the preamp out with the poweramp in.
If still no sound; Probably a bad jack conncetor. Wich one -> that's for the next post.
5. Set the reverb control at 8 and shake the amp.
Do you hear the spring ratlle?
It'a a pitty you do not have a generator and a scope. (I assume)
A generator is not absolutely needed, a scope or signal tracer; yes.
That way you can feed a signal into the input jack and follow it up to the speaker.
You can then find out where the problem is.
Curious wht this will bring.
ps: The hot rod De veille is not in for repair yet.
Maybe by the end of the week.
We have checked allmost everything now and all seems ok.
You hear a loud hum when you measure at pin 5 of V4 and V5.
The dc values of the preamp tubes are also reasonable ok.
Plugging in a guitar dosn't produce any sound; only hum.
I'm thinking in a problem with either the input jack or the Power amp in jack.
These are notorious for their reliablity.
Maybe the solderjoints have been damaged with removing and inserting the pcb into the chassis.
A possibility is also the flatcables that go from the main pcb to the pcb with the tubes on.
1. Check (without any voltage applied!!!) if some wires are not broken on either side.
2. If that all is ok, plug your guitar in to the poweramp input jack and see if you hear any sound.
If yes; the power stage is ok.
If no; have a look at the jack (J4) for bad solderjoints.
3. If yes, Plug your guitar into the input jack and connect, if possible, the preamp out to another amp.
Do you hear any sound?
4. If yes, Connect the preamp out with the poweramp in.
If still no sound; Probably a bad jack conncetor. Wich one -> that's for the next post.
5. Set the reverb control at 8 and shake the amp.
Do you hear the spring ratlle?
It'a a pitty you do not have a generator and a scope. (I assume)
A generator is not absolutely needed, a scope or signal tracer; yes.
That way you can feed a signal into the input jack and follow it up to the speaker.
You can then find out where the problem is.
Curious wht this will bring.
ps: The hot rod De veille is not in for repair yet.
Maybe by the end of the week.
Let me ask you this... The resistors, do they have to be installed a certain way? Do they flow in one direction? Next would the filter capacitors have anything to do with the draining of the B+? I have been carefully studying the board for any signs of anything unusual. I have noticed that almost all the resistors are installed banded the same way. I dont know if this is coinicidence. I will check the pot and input connections as you mentioned because that is one thing I havent checked.
Q - "The resistors, do they have to be installed a certain way? Do they flow in one direction?"
A - No
Q - Next would the filter capacitors have anything to do with the draining of the B+?
A - Could be. If they are leaking
Q - I have noticed that almost all the resistors are installed banded the same way. I dont know if this is coinicidence.
A - Yes
Q - I will check the pot and input connections as you mentioned because that is one thing I havent checked.
A - I did not asked for checking the pot. Set the pot at 8. Wiggle the amp and lsiten to an eventual ratlle.
The tests as described in post 47 and numbered 1 to 5 are tests to exclude some parts of the amp and mark them as OK or Suspicious.
If suspicius other tests will close up to an the eventual problem.
It's of no use jumping left and right and try this and that without a strategy in mind.
Can you do the tests, 1 to 5 and come back with the results.
Good luck.
A - No
Q - Next would the filter capacitors have anything to do with the draining of the B+?
A - Could be. If they are leaking
Q - I have noticed that almost all the resistors are installed banded the same way. I dont know if this is coinicidence.
A - Yes
Q - I will check the pot and input connections as you mentioned because that is one thing I havent checked.
A - I did not asked for checking the pot. Set the pot at 8. Wiggle the amp and lsiten to an eventual ratlle.
The tests as described in post 47 and numbered 1 to 5 are tests to exclude some parts of the amp and mark them as OK or Suspicious.
If suspicius other tests will close up to an the eventual problem.
It's of no use jumping left and right and try this and that without a strategy in mind.
Can you do the tests, 1 to 5 and come back with the results.
Good luck.
Not strictly true - while it makes no electrical difference it's common practice to fit all resistors the same way round as it looks tidier.
So not 'coincidence', but deliberately planned that way.
Hello Nigel,
When I entered Bel Telephone in the early 80's, yes that whas done.
But later on it al depended on the way they were mounted on the insertion tapes for manufacturing.
It looks indeed tidier. But who is doing it still?
So the answer should be : "nice way to build a pcb but not absolutely necessary"
When I entered Bel Telephone in the early 80's, yes that whas done.
But later on it al depended on the way they were mounted on the insertion tapes for manufacturing.
It looks indeed tidier. But who is doing it still?
So the answer should be : "nice way to build a pcb but not absolutely necessary"
Check (without any voltage applied!!!) if some wires are not broken on either side.
All wires have good contact and continuity.
2. If that all is ok, plug your guitar in to the poweramp input jack and see if you hear any sound.
If yes; the power stage is ok.
If no; have a look at the jack (J4) for bad solderjoints.
Plug into power amp, just the same hum.
3. If yes, Plug your guitar into the input jack and connect, if possible, the preamp out to another amp.
Do you hear any sound?
Plug into preamp into another amp and no sound.
4. If yes, Connect the preamp out with the poweramp in.
If still no sound; Probably a bad jack conncetor. Wich one -> that's for the next post.
5. Set the reverb control at 8 and shake the amp.
Do you hear the spring ratlle?
I heard the spring rattling from the back but not through the speakers.
I checked all the input jacks and the solder joints seem good and no wiggle.
All wires have good contact and continuity.
2. If that all is ok, plug your guitar in to the poweramp input jack and see if you hear any sound.
If yes; the power stage is ok.
If no; have a look at the jack (J4) for bad solderjoints.
Plug into power amp, just the same hum.
3. If yes, Plug your guitar into the input jack and connect, if possible, the preamp out to another amp.
Do you hear any sound?
Plug into preamp into another amp and no sound.
4. If yes, Connect the preamp out with the poweramp in.
If still no sound; Probably a bad jack conncetor. Wich one -> that's for the next post.
5. Set the reverb control at 8 and shake the amp.
Do you hear the spring ratlle?
I heard the spring rattling from the back but not through the speakers.
I checked all the input jacks and the solder joints seem good and no wiggle.
I would expect components to generally be the same way round on the tapes? - those I've seen have been (I was given a load of filled tapes from an exhibition where insertion machines were on display).
Anyone with a sense of pride and using good quality construction 😀
This is weird;
1. No sound from the preamp.
2. No sound from the poweramp.
3. No sound from the reverbsprings (but that can be caused by the poweramp)
The voltages on the valves are, let's say OK. So let's forget that for a while.
Let's concentrate on the reproduction of sound.
We have a guitar.
We have a cable.
We have an amp with his speakers.
We know the speakers are working and the powestage to.
(Proof is the hum if you touch pin 5 of V4 or 5)
Next to check is the source of the sound.
Is your cable OK.
Measure continuety of the wires in the cable with an ohm meter.
From tip to tip and from screen to screen or try it on an other amp.
Is your guitar ok?
Check on another amp
If both last test are good; then there MUST be a problem with on of the connectors if not both. J1, J2 (Input jacks) and J4 (poweramp in jack)
Maybe a stupid remark but it happens sometime; Is your speaker connected to J7 or J8?
If all this gives no results we have to start from scratch again.
It happens as we begin to loos focus.
1. No sound from the preamp.
2. No sound from the poweramp.
3. No sound from the reverbsprings (but that can be caused by the poweramp)
The voltages on the valves are, let's say OK. So let's forget that for a while.
Let's concentrate on the reproduction of sound.
We have a guitar.
We have a cable.
We have an amp with his speakers.
We know the speakers are working and the powestage to.
(Proof is the hum if you touch pin 5 of V4 or 5)
Next to check is the source of the sound.
Is your cable OK.
Measure continuety of the wires in the cable with an ohm meter.
From tip to tip and from screen to screen or try it on an other amp.
Is your guitar ok?
Check on another amp
If both last test are good; then there MUST be a problem with on of the connectors if not both. J1, J2 (Input jacks) and J4 (poweramp in jack)
Maybe a stupid remark but it happens sometime; Is your speaker connected to J7 or J8?
If all this gives no results we have to start from scratch again.
It happens as we begin to loos focus.
this may be a silly question and may alrdy hav been asked (i've been on holiday) but you hav pluged the guitar and lead into another amp to make sure they work ok.?
ah yes i see we did ask that my mistake
ah yes i see we did ask that my mistake
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