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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Mon Feb 07, 2011 9:58 am
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Be sure everything's Plugged in correctly. Be sure the speaker and reverb are plugged into the correct jacks and not onto an extension speaker jack. I'd double check the polarity on the caps and diodes too as well as cold solder joints or lifted traces. You did a lot of work in there. I'd just double check everything.

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Mon Feb 07, 2011 3:24 pm
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richardo wrote:
...Any ideas please... have I wired the input jacks wrong, although I did test them with a meter following Justin Holtons instructions...


First, make sure that you reconnected the green ground wire on the right side of the main circuit board. Then, you may want to check the DC voltage test points on the amp (indicated on the schematic), to make sure that all of the DC power supplies are good, ie B+ voltage, Z, Y, X, C-, both positive and negative 16 volts supplies, etc. Measure the DC voltages, putting the negative lead of your meter on the chassis, and the positive meter lead to the test points. The test points are labeled on the schematic, but aren't labeled on the amp, you will have to use components for test points. Example, the B+ voltage can be read at the positive side of C34 on the main circuit board (should be around 471 volts), and the C- voltage can be read where R 55 and R 54 connect together on the tube circuit board (should be around 49.6 volts). You may have to refer to the component layout sheet of the schematics to find the component locations.

It isn't unusual to have a different voltage reading than what the schematic shows, but they should be fairly close. If all of your test points for the DC voltages check out, then I would suspect the input jacks wiring. Write down all of your test point readings for future reference. If I remember correctly, there are a couple of different types of circuit boards, so make sure that your wiring matches the board that you have. Check these things and let us know what you find. :idea:

Edit:
Maybe your input jacks wiring looks like this?
Image

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Tue Feb 08, 2011 1:17 am
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63supro wrote:
Be sure everything's Plugged in correctly. Be sure the speaker and reverb are plugged into the correct jacks and not onto an extension speaker jack. I'd double check the polarity on the caps and diodes too as well as cold solder joints or lifted traces. You did a lot of work in there. I'd just double check everything.


Thanks Supro for chiming in....
Yep, done all that..... always double checked diodes, caps to make sure I got the + in the right slot before soldering, have rechecked no worries ...
Still no go.

Thanks though!

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Tue Feb 08, 2011 2:21 am
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shimmilou wrote:
richardo wrote:
...Any ideas please... have I wired the input jacks wrong, although I did test them with a meter following Justin Holtons instructions...


First, make sure that you reconnected the green ground wire on the right side of the main circuit board. Then, you may want to check the DC voltage test points on the amp (indicated on the schematic), to make sure that all of the DC power supplies are good, ie B+ voltage, Z, Y, X, C-, both positive and negative 16 volts supplies, etc. Measure the DC voltages, putting the negative lead of your meter on the chassis, and the positive meter lead to the test points. The test points are labeled on the schematic, but aren't labeled on the amp, you will have to use components for test points. Example, the B+ voltage can be read at the positive side of C34 on the main circuit board (should be around 471 volts), and the C- voltage can be read where R 55 and R 54 connect together on the tube circuit board (should be around 49.6 volts). You may have to refer to the component layout sheet of the schematics to find the component locations.

It isn't unusual to have a different voltage reading than what the schematic shows, but they should be fairly close. If all of your test points for the DC voltages check out, then I would suspect the input jacks wiring. Write down all of your test point readings for future reference. If I remember correctly, there are a couple of different types of circuit boards, so make sure that your wiring matches the board that you have. Check these things and let us know what you find. :idea:

Edit:
Maybe your input jacks wiring looks like this?
Image


Thanks Shimmilou for your time...
Have had the board out again and double checked all things...
re- slotted the board in and connected it all up ...
Still the same result, no sound at all apart from the horrid crackling...
Any way, I checked a couple of test points....

Only DC at this stage as my test meter hasn't the res for the finer VAC readings, but will get another tomorrow..
TP 3 @ C1= 2.16vdc (1.67vdc recommended)
TP 5 @ R10= 2.19vdc (1.77vdc recommended)
TP 8 @ C8= 2.18vdc (1.71vdc recommended)

DC + side of C34 cap measured 492vdc... (471vdc recommended)

Not much else I can test till I grab another tester.

Btw, my board's different than the one you posted...

here's a link to before recap
http://www.baytop-observatory.com/image ... 0recap.jpg

and after recap... excuse all the tags on transformer wires, also you'll see I've used the same input jacks as you.
http://www.baytop-observatory.com/image ... 0recap.jpg

Any insight with limited input I have so far ??? Voltages a bit high??

Thanks again
Rich

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Last edited by richardo on Tue Feb 08, 2011 5:50 am, edited 1 time in total.

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Tue Feb 08, 2011 5:25 am
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Did you ever rule-out the "nackered tube" idea? It sounds like you may have a shorted 12AX7 or even a funky power tube (bad grid)--- or socket (which is more common with older units). Did you measure B+ with or without load (with power tubes in & speakers connected, or not?). Without load, it will usually give you higher value.


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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Tue Feb 08, 2011 5:48 am
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BMW2002Ti wrote:
Did you ever rule-out the "nackered tube" idea? It sounds like you may have a shorted 12AX7 or even a funky power tube (bad grid)--- or socket (which is more common with older units). Did you measure B+ with or without load (with power tubes in & speakers connected, or not?). Without load, it will usually give you higher value.


Thanks BM for your input...
I did replace the whole tube set as the power tubes had cracked plastic alignment posts.. (amazing it worked at all )
I bought a whole new set... 2 ECC83S standard &1 balanced ECC83S for pre amp and 2 matched 6L6GC pair from JJ's for this Deville as it has no bias.
I did the test with all valves in and speakers connected....

Cheers
Rich

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Tue Feb 08, 2011 6:45 am
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Ok... re-read your OP (that always helps :wink: )... Is the following link a schematic of your amp? CR20 is a diode in a full-wave bridge that feeds 4560 chips (part of the footswitch circuit). I'm a wondering about those chips? I presume after you replaced the diode, you are getting + and - 16 VDC of the read points? If not, the zeners (CR22 & 23) may need looking at.

If you are getting +/- 16 VDC off the PS... then you prolly need to look at those 4560's. Which to tell you the truth, I USED to just replace, as they were relatively cheap in early 2000's). UNFORTUNATELY, it's getting easier to find 1950's NOS RCA 6L6GC black plates, than some of these older (1980-90's) chips... Just ask anyone trying to revive their old TS-9 Screamer.

You wouldn't happen to know anyone with a silmiar (and WORKING) Blues Deville... that you can kinda "borrow" a circuit board? :o That would be my only reasonable suggestion, as I think you've done just about all the usual "tube-type circuit" fixes, to no avail.

These dang IC's blow all the time. And the manufacturers often limit production runs. As newer and better (and smaller and cheaper) products could out. I think you could try a 4562 (better double check my item number).Sorry for the bad news. (This is kinda why I stick to P2P older amps, to fix).

http://www.ampwares.com/schematics/blues_deville.pdf

Try this place for replacement parts and wiring diagram:

http://www.national.com/pf/LM/LM4562.html#Overview


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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Tue Feb 08, 2011 7:29 am
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richardo wrote:
...Any way, I checked a couple of test points....

Only DC at this stage as my test meter hasn't the res for the finer VAC readings, but will get another tomorrow..
TP 3 @ C1= 2.16vdc (1.67vdc recommended)
TP 5 @ R10= 2.19vdc (1.77vdc recommended)
TP 8 @ C8= 2.18vdc (1.71vdc recommended)

DC + side of C34 cap measured 492vdc... (471vdc recommended)...


Don't worry about the AC voltages, those test points are measured with a signal injected on the input of the amp. Just check all of the DC voltages test points, especially the C-, the +/- 16 volt supplies, and the B+, Z, Y, and X. It is OK for your voltages, like the B+, to be higher (492 VDC B+ is OK). I presume that the light on the amp comes on, indicating the AC filament voltage is good?

Also, don't worry about the chips, the amp will still work without them. The chips are for the reverb, preamp out, and the foot switch. Make sure all of the DC supplies are good first, then go from there. :idea:

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Wed Feb 09, 2011 5:58 am
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BMW2002Ti wrote:
Ok... re-read your OP (that always helps :wink: )... Is the following link a schematic of your amp? CR20 is a diode in a full-wave bridge that feeds 4560 chips (part of the footswitch circuit). I'm a wondering about those chips? I presume after you replaced the diode, you are getting + and - 16 VDC of the read points? If not, the zeners (CR22 & 23) may need looking at.

If you are getting +/- 16 VDC off the PS... then you prolly need to look at those 4560's. Which to tell you the truth, I USED to just replace, as they were relatively cheap in early 2000's). UNFORTUNATELY, it's getting easier to find 1950's NOS RCA 6L6GC black plates, than some of these older (1980-90's) chips... Just ask anyone trying to revive their old TS-9 Screamer.

You wouldn't happen to know anyone with a silmiar (and WORKING) Blues Deville... that you can kinda "borrow" a circuit board? :o That would be my only reasonable suggestion, as I think you've done just about all the usual "tube-type circuit" fixes, to no avail.

These dang IC's blow all the time. And the manufacturers often limit production runs. As newer and better (and smaller and cheaper) products could out. I think you could try a 4562 (better double check my item number).Sorry for the bad news. (This is kinda why I stick to P2P older amps, to fix).

http://www.ampwares.com/schematics/blues_deville.pdf

Try this place for replacement parts and wiring diagram:

http://www.national.com/pf/LM/LM4562.html#Overview


Hi BMW...
BTW, the schematic you linked to is the correct one for my Deville.

No one in my town has such a beast as my Deville, a couple of Hot rod Devilles. One of which belongs to my long time band buddy of twenty plus years, I know he wouldn't want me to go messin' with his rig... :lol: After all the poor beggar had one of those poxy Marshall combos, while it had a nice thick warm clean channel, he always had problems with the thing dropping in and out... while he has a little drama with the harshness with his HRD, he's learnt to tame it :P .

OK, checked TP's on U3 IC chip.. as follows
TP30 2.06vdc (recommended .6vdc)
TP31 -15.25vdc (recom 15vdc)
TP32 15.34vdc (recom 15vdc)

Checked TP's on U2 IC chip
TP33 ..... nothing, zero, nada!
TP34 -15.40vdc (recom 15vdc)

Also tested TP 26 and there's no reading.

Mmm, so what do you think??

Never mind, it's not really bad news to me, I use to run a computer repair and building service in my little town.... so I never expect anything, then I can never get disappointed... but I can loose patience :shock: :evil: :lol:

Ok, thanks again, good to have a sounding board with things I know little about.
Hear from you soon on what you reckon the go is.

All the best
Rich

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Last edited by richardo on Wed Feb 09, 2011 6:12 am, edited 1 time in total.

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Wed Feb 09, 2011 6:11 am
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shimmilou wrote:
richardo wrote:
...Any way, I checked a couple of test points....

Only DC at this stage as my test meter hasn't the res for the finer VAC readings, but will get another tomorrow..
TP 3 @ C1= 2.16vdc (1.67vdc recommended)
TP 5 @ R10= 2.19vdc (1.77vdc recommended)
TP 8 @ C8= 2.18vdc (1.71vdc recommended)

DC + side of C34 cap measured 492vdc... (471vdc recommended)...


Don't worry about the AC voltages, those test points are measured with a signal injected on the input of the amp. Just check all of the DC voltages test points, especially the C-, the +/- 16 volt supplies, and the B+, Z, Y, and X. It is OK for your voltages, like the B+, to be higher (492 VDC B+ is OK). I presume that the light on the amp comes on, indicating the AC filament voltage is good?

Also, don't worry about the chips, the amp will still work without them. The chips are for the reverb, preamp out, and the foot switch. Make sure all of the DC supplies are good first, then go from there. :idea:


Hi Shim...
Yep the power on light is good and the 'drive select' light comes on when I depress the switch... all tubes light up..

Here's the other DCV TP's I checked, and posted to BMW....
U3 IC
TP30 2.06vdc (recommended .6vdc)
TP31 -15.25vdc (recom 15vdc)
TP32 15.34vdc (recom 15vdc)
U2 IC
TP33 ..... nothing, zero, nada!
TP34 -15.40vdc (recom 15vdc)

Also tested TP 26 and there's no reading.

I'm open for any thoughts as to the next step...

Your thoughts/ ideas are much appreciated to get the ol' girl going again.
The lads are keen to get crankin' again 8)

All the best
Rich

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Wed Feb 09, 2011 7:35 am
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richardo,

TP30, and TP33 are a "greater than" >, or "less than" <, depending on the switch setting for which channel is selected (TP30), or whether the reverb is on (TP33). So zero would be "less than", and 2 would be "greater than", try switching channels and see if the voltage changes at TP30, it should (note two readings for some test points).

For TP26, check your voltage at Y, and see if you have around 420 volts. If you have the voltage at Y, then try another phase inverter tube (V3). If you do not have the voltage at Y, then something in the power supply may be wrong. :idea:

Again, check the voltages at X, Y and Z, and the C- too! Don't just check some of the voltages, check them all. They are all DC voltages. :)

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Thu Feb 10, 2011 5:14 am
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shimmilou wrote:
richardo,


For TP26, check your voltage at Y, and see if you have around 420 volts. If you have the voltage at Y, then try another phase inverter tube (V3). If you do not have the voltage at Y, then something in the power supply may be wrong. :idea:

Again, check the voltages at X, Y and Z, and the C- too! Don't just check some of the voltages, check them all. They are all DC voltages. :)


Thanks again Shimmilou for your responses....
and all you guys on here that have chimed in, you have been great trying to help me sort what started out as a re cap, resolder a couple of diodes and resistors sort of job into me going into no mans land... (that is for this man :? )

Ok, I'm not sure on how to measure the plate voltages... i have identified where pins 1- 8 are on the power tubes/sockets and also the 1-10 on the pre amp tubes, but as far as knowing what voltage to look for in what pin with the positive probe and where to place the negative probe while measuring.... and do I remove the valves when doing this.... this is where I have no idea . Where are points X, Y and Z, and the C- .. no idea!!
As this is high voltage stuff, and have many new parts, I won't go any further until I know exactly what I'm doing.
If I can see exactly how to do these measurements, I'll go for it, but if there is no clear explanation, as much as it pains me, I might have to send the amp off to the big smoke 8 hours away and get the Fender techs to sort it and pay the bucks I don't have... but that's life.

Any ways, either way, I thank you all for your gracious help and patience with a novice !!
All the best
Rich

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Thu Feb 10, 2011 8:06 am
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richardo,

I thought that you had a copy of the schematic, here is the link.

http://support.fender.com/schematics/guitar_amplifiers/Blues_DeVille_schematic.pdf

In the lower right side of the schematic, the power supply section, note the little arrows pointing up that are labeled "B+", "Z", "Y", "X" etc. The B+ for example is the positive side of the C34 capacitor, Z is the positive side of C41 capacitor, Y is the positive side of C45 capacitor, and X is the positive side of C46 capacitor. The "C-" voltage can be read where R53 and R54 connect together on the tube socket board. For all of these readings of DC voltage, put the negative lead of your meter on the chassis metal, and touch the positive lead on the test points, one at a time keeping the negative lead on the chassis. If you have those voltages close to what the schematic shows, that indicates that the power supply is OK. Your voltage readings might be different, and that's OK, they might be higher than what the schematic shows. I agree with BMW2002Ti, maybe a bad tube is what caused the problems with the power supply to begin with (maybe the phase inverter V3). That is why I'm particularly interested in the fact that you have no voltage at TP26, this may indicate that the Y voltage is missing, or something is wrong in the phase inverter circuit (V3). :)

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Thu Feb 10, 2011 11:19 pm
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shimmilou wrote:
richardo,

I thought that you had a copy of the schematic, here is the link.

http://support.fender.com/schematics/guitar_amplifiers/Blues_DeVille_schematic.pdf

In the lower right side of the schematic, the power supply section, note the little arrows pointing up that are labeled "B+", "Z", "Y", "X" etc. The B+ for example is the positive side of the C34 capacitor, Z is the positive side of C41 capacitor, Y is the positive side of C45 capacitor, and X is the positive side of C46 capacitor. The "C-" voltage can be read where R53 and R54 connect together on the tube socket board. For all of these readings of DC voltage, put the negative lead of your meter on the chassis metal, and touch the positive lead on the test points, one at a time keeping the negative lead on the chassis. If you have those voltages close to what the schematic shows, that indicates that the power supply is OK. Your voltage readings might be different, and that's OK, they might be higher than what the schematic shows. I agree with BMW2002Ti, maybe a bad tube is what caused the problems with the power supply to begin with (maybe the phase inverter V3). That is why I'm particularly interested in the fact that you have no voltage at TP26, this may indicate that the Y voltage is missing, or something is wrong in the phase inverter circuit (V3). :)


Shimmilou.... aaahhh thanks mate!! That's what I needed to know.... as for the schematic, I already have it.... have been studying it so much that 'I couldn't see the forest for the trees'!! Found the B+, C-, x, y & z points. Mmmm, domestic blindness or early onset of Alzheimers :P

Ok, as shown in a previous post I did test the B+ (C34) and came out near spec...
Today when I got home from work went to try B+ again and blew the fuse, almost like the thing is shorting somewhere.... ???
I read on another post somewhere a guy had a similar prob, same amp, although his happened every time he switched from standby; it turned out to be the HT Choke.. or perhaps it could be one of the transformer/ power supplies.. ??
Weird, as I tested this before and it was ok.... maybe I've done in one of my new 6L6GC power tubes with all the fritzin' around I've done... :shock: gol darn fickle things...
Gonna get to the bottom of this :mrgreen:

Your input as usual will be much appreciated.

All the best
Rich

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Post subject: Re: 93 blues deville fried diode- long winded..
Posted: Fri Feb 11, 2011 1:05 am
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Hmmm, I hate to ask...but, are you sure that you had your meter set to DC volts when you checked the B+ again? Or, maybe you accidentally shorted two points with your meter lead? You haven't mention the fuse blowing before, and if the meter was accidentally set to amps instead, that could have blown the fuse (don't ask me how I know that :oops: ). Typically, if you have a short like that, the fuse would have blown long before you measured the voltage, but anything is possible.

You indicated that you measured the voltages with all tubes removed, that is a good idea to leave the tubes out until you find the problem. Replace the fuse and try to measure the power supply voltages with meter set to DC volts at B+, X, Y and Z. I am still focused on the fact that you had no voltage at TP26 before and yet had the B+ voltage, so see if there is voltage at Y especially. :idea:

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