Frontman 212R no output on drive channel

bnwitt · 01-08-2009, 11:47 PM

I just received a Fender frontman 212R for repair with no output on the drive channel. The normal channel sounds fine and the reverb works when in the normal channel mode.

However, if you swithch to the drive channel with the panel button or the footswitch, the amp goes silent. Does anyone have a schematic on this amp? I'm working off the non-reverb one at the moment. I'm going to pull the chassis and look for obvious problems.

black_labb · 01-09-2009, 12:00 AM

i had an issue with one, and couldnt find the schematic either. my issue was the resistors dropping the voltage, but yours wouldnt be. sorry i couldnt be any help

bnwitt · 01-09-2009, 12:11 AM

I appreciate the response black_labb. I did find a schematic for an FM212R so I'll attach it for you. Looking at the schem, there are any number of devices that could fail and drop the drive channel signal including several jfets, opamps and the contour switch along with many others. Here's the funny thing. I just played with the contour switch a little and the drive channel came back on. I'm going to pull the chassis and check all connections.

bnwitt · 01-09-2009, 01:00 AM

Ok, now I have a question for anyone familiar with this amp. It looks to me like the drive channel when turned on just swamps out the signal for the normal channel and doesn't actually switch the normal channel's output off. Is that the case?

Enzo · 01-09-2009, 01:19 AM

Looks that way, unless the gate circuit of Q5 is totally mis-drawn.

bnwitt · 01-09-2009, 07:04 PM

Sort of makes you wonder why Q5 is even there if it is really wired that way. Wired differently with the gate controlled by the channel switching it would shunt the signal to ground right?

Enzo · 01-10-2009, 12:52 AM

I have no idea what Q5 is all about as drawn.

bnwitt · 01-10-2009, 05:21 AM

Quote:

Originally Posted by Enzo

I have no idea what Q5 is all about as drawn.

Well then there is no hope for me to understand it.

Obviously it is drawn wrong.

Enzo · 01-10-2009, 05:57 AM

Sure you can. Find Q5, and the gate diode D9, on the board. Follow the traces from the cathode of D9 and see if it actually goes to C10 like the drawing, or if it instead connects to the DRIVE-SEL line.

Actually, don;t bother to trace it, just measure continuity from cathode of D9 to negative end of C10. COntinuity or not? Then measure from cathode D9 to some point on the DRIVE-SEL line like the cathodes of D11 or D14. COntinuity or not. No need to flip the board.

Mars Amp Repair · 01-10-2009, 02:30 PM

As an aside,
Did you know that Fender no longer authorizes warranty repair work on the FM212?.

They send an exchange amp. Wild to think it's cheaper for them to ship one of these & pay to have the defective one shipped back to them, then to have me fix it for their measly $50.00.

Surprized (and disappointed) the heck outta me...glen

bnwitt · 01-10-2009, 03:43 PM

Enzo,
Unfortunately the amp is back in the hands of the owner after cleaning the Mid Contour switch, everything was working fine. If it comes back in I'll trace things out.

Glen,
I had heard that. It doesn't make a lot of sense unless the failure rate is really low and they've not been happy with the quality of warranty repairs from authorized service centers. I would think sending a new amp might not fix the problem when it is something connected to a design issue that has not been corrected with a redesign. They definitely lose the field tech feedback aspect that way. From what I've read in this forum and others this seems to be the way of future for alot of manufacturers. Thank goodness for warranty expiration dates.

Enzo · 01-10-2009, 06:48 PM

The FM212R is about the largest throw-away Fender. There was also a bass combo, a (something)60 that surprised me the first time.

They don't pay us $50 because the amps are so inexpensive and profit margins so low. It makes more sense to their bottom line to send another amp.

I do note that the little Frontman practice amps and similar, they don;t want back. The FM212R last time I did one, they sent a call tag for it.

Mars Amp Repair · 01-10-2009, 11:15 PM

BTW...the new Peavey VYPR 1x12 combo looks alot like a Beringer inside. Only 3 pcb's that look unservicable...REALLLLL JUNK!

fortunately (I guess), PV just does board swaps on these little 'gems'. Makes me sick that this once proud American company has had to stoop to making this garbage... economics & all.

I hope the better ones remain quality & don't all go this route for Peavey. g

Mars Amp Repair · 01-10-2009, 11:16 PM

Enzo...that's the Rumble 60 you're thinking of...g

bnwitt · 01-11-2009, 01:04 AM

Well I just finished servicing a TOA A-912MK2 P.A. amplifier and I was blown away by their quality. The unit failed after a power outage due to a spike and the power board fried. Excellent construction inside and easy to service. I ordered the power board and it came in a composite break apart that included the condenser rectifier board, the output jack board and the LED MV board. All for a very reasonable price. Some American companies are still doing the right thing.

Enzo · 01-13-2009, 02:20 AM

Well, OK, except TOA is a Japanese company.

bnwitt · 01-13-2009, 04:06 AM

Quote:

Originally Posted by Enzo

Well, OK, except TOA is a Japanese company.

Well their Stateside office in Wa. was very helpful. I guess our American manufacturers have lost their edge.

phillhorse · 03-02-2009, 10:37 AM

I cannot seem to download the pdf schematic:-(( Any ideas why?

Enzo · 03-02-2009, 10:56 AM

In post #3? I just clicked on it and it opened right up for me.

phillhorse · 03-02-2009, 06:42 PM

That's strange, I get a dialoge box saying: either Im not logged in (I am), I dont have access privaliges, or my account has been disabled or my account has not been activated.
I only created the account last night and to date I have not received a "Activation" email only a welcome one...funny though that I can post?

Is there any way to post this attachment to my email address?

Enzo · 03-03-2009, 12:54 AM

send a note to tboy explaining your difficulty

bnwitt · 03-03-2009, 03:09 AM

email me a bnwitt at hotmail dot com and I will send you the schematic

jorshb · 09-24-2009, 08:16 PM

Last night i was playing the guitar with my frontman212R and happens exactly the same when i turn the distortion channel on whether with the footswitch or the bottom on the front of amp the sounds go OFF !!! or sounds strange... ?? does anyone knows how to fix this ?? ?

davetutt · 01-21-2010, 09:13 AM

Hi folks

I have had several of these through my workshop.
The loss of the channel has turned out to be either dry joints at the resistor (1k2 1watt) next to the main smoothing capacitor. I have yet to find any serious issue in the low level electronics of the amp. I have however found that the main rectifier diodes are less than reliable under load (all measure okay when removed from the board) and the only option is to replace them all. Likewise the down stream zener regulator for the op-amps and low level circuits (+-16 volts or so) seems to fail when the 5 watt resistors have dry joints and disconnect the supply. be aware that this can cause issues in some other parts of the circuitry especially if one supply line goes missing and is left on humming to itself!

After all this time the speakers will be getting old and tired. I replace these with Celestion 12K100 drivers as they are significantly better. I also make two alterations to the cabinet to solve a number of rattles. These are a short back panel made from MDF or similar that doesn't cover all the back area and includes two holes of approximately 3 inches to allow the speakers to breath. The second change is a brace between the new back and the front baffle made from 3x2 timber. Also, the grill cloth slaps back onto the grill frame causing it to buzz, especially if you use a 7 string guitar which goes down to 55hz so packing out the grill fabric with a thin strip of door sealing foam stops this happening.

Hope that helps. Any questions let me know. This is a great amp and so far i haven't found any issues that are too serious to fix!

01-08-2009, 11:47 PM	#1
bnwitt Senior Member Join Date: Nov 2008 Location: Southern California Posts: 409	Frontman 212R no output on drive channel I just received a Fender frontman 212R for repair with no output on the drive channel. The normal channel sounds fine and the reverb works when in the normal channel mode. However, if you swithch to the drive channel with the panel button or the footswitch, the amp goes silent. Does anyone have a schematic on this amp? I'm working off the non-reverb one at the moment. I'm going to pull the chassis and look for obvious problems.

01-09-2009, 01:19 AM	#5
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Looks that way, unless the gate circuit of Q5 is totally mis-drawn. __________________ Education is what you're left with after you have forgotten what you have learned.

01-10-2009, 12:52 AM	#7
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	I have no idea what Q5 is all about as drawn. __________________ Education is what you're left with after you have forgotten what you have learned.

01-10-2009, 05:57 AM	#9
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Sure you can. Find Q5, and the gate diode D9, on the board. Follow the traces from the cathode of D9 and see if it actually goes to C10 like the drawing, or if it instead connects to the DRIVE-SEL line. Actually, don;t bother to trace it, just measure continuity from cathode of D9 to negative end of C10. COntinuity or not? Then measure from cathode D9 to some point on the DRIVE-SEL line like the cathodes of D11 or D14. COntinuity or not. No need to flip the board. __________________ Education is what you're left with after you have forgotten what you have learned.

01-10-2009, 06:48 PM	#12
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	The FM212R is about the largest throw-away Fender. There was also a bass combo, a (something)60 that surprised me the first time. They don't pay us $50 because the amps are so inexpensive and profit margins so low. It makes more sense to their bottom line to send another amp. I do note that the little Frontman practice amps and similar, they don;t want back. The FM212R last time I did one, they sent a call tag for it. __________________ Education is what you're left with after you have forgotten what you have learned.

01-09-2009, 12:00 AM	#2
black_labb Senior Member Join Date: Apr 2007 Location: sydney australia Posts: 777	i had an issue with one, and couldnt find the schematic either. my issue was the resistors dropping the voltage, but yours wouldnt be. sorry i couldnt be any help

01-09-2009, 01:00 AM	#4
bnwitt Senior Member Join Date: Nov 2008 Location: Southern California Posts: 409	Ok, now I have a question for anyone familiar with this amp. It looks to me like the drive channel when turned on just swamps out the signal for the normal channel and doesn't actually switch the normal channel's output off. Is that the case?

01-09-2009, 07:04 PM	#6
bnwitt Senior Member Join Date: Nov 2008 Location: Southern California Posts: 409	Sort of makes you wonder why Q5 is even there if it is really wired that way. Wired differently with the gate controlled by the channel switching it would shunt the signal to ground right?

01-10-2009, 02:30 PM	#10
Mars Amp Repair Senior Member Join Date: Sep 2006 Location: Englewood, CO Posts: 673	As an aside, Did you know that Fender no longer authorizes warranty repair work on the FM212?. They send an exchange amp. Wild to think it's cheaper for them to ship one of these & pay to have the defective one shipped back to them, then to have me fix it for their measly $50.00. Surprized (and disappointed) the heck outta me...glen

01-10-2009, 03:43 PM	#11
bnwitt Senior Member Join Date: Nov 2008 Location: Southern California Posts: 409	Enzo, Unfortunately the amp is back in the hands of the owner after cleaning the Mid Contour switch, everything was working fine. If it comes back in I'll trace things out. Glen, I had heard that. It doesn't make a lot of sense unless the failure rate is really low and they've not been happy with the quality of warranty repairs from authorized service centers. I would think sending a new amp might not fix the problem when it is something connected to a design issue that has not been corrected with a redesign. They definitely lose the field tech feedback aspect that way. From what I've read in this forum and others this seems to be the way of future for alot of manufacturers. Thank goodness for warranty expiration dates.

01-10-2009, 11:15 PM	#13
Mars Amp Repair Senior Member Join Date: Sep 2006 Location: Englewood, CO Posts: 673	BTW...the new Peavey VYPR 1x12 combo looks alot like a Beringer inside. Only 3 pcb's that look unservicable...REALLLLL JUNK! fortunately (I guess), PV just does board swaps on these little 'gems'. Makes me sick that this once proud American company has had to stoop to making this garbage... economics & all. I hope the better ones remain quality & don't all go this route for Peavey. g

01-10-2009, 11:16 PM	#14
Mars Amp Repair Senior Member Join Date: Sep 2006 Location: Englewood, CO Posts: 673	Enzo...that's the Rumble 60 you're thinking of...g

01-11-2009, 01:04 AM	#15
bnwitt Senior Member Join Date: Nov 2008 Location: Southern California Posts: 409	Well I just finished servicing a TOA A-912MK2 P.A. amplifier and I was blown away by their quality. The unit failed after a power outage due to a spike and the power board fried. Excellent construction inside and easy to service. I ordered the power board and it came in a composite break apart that included the condenser rectifier board, the output jack board and the LED MV board. All for a very reasonable price. Some American companies are still doing the right thing.

01-13-2009, 02:20 AM	#16
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Well, OK, except TOA is a Japanese company. __________________ Education is what you're left with after you have forgotten what you have learned.

03-02-2009, 10:37 AM	#18
phillhorse Junior Member Join Date: Mar 2009 Posts: 4	I cannot seem to download the pdf schematic:-(( Any ideas why?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

03-02-2009, 10:56 AM	#19
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	In post #3? I just clicked on it and it opened right up for me. __________________ Education is what you're left with after you have forgotten what you have learned.

03-02-2009, 06:42 PM	#20
phillhorse Junior Member Join Date: Mar 2009 Posts: 4	That's strange, I get a dialoge box saying: either Im not logged in (I am), I dont have access privaliges, or my account has been disabled or my account has not been activated. I only created the account last night and to date I have not received a "Activation" email only a welcome one...funny though that I can post? Is there any way to post this attachment to my email address?

03-03-2009, 12:54 AM	#21
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	send a note to tboy explaining your difficulty __________________ Education is what you're left with after you have forgotten what you have learned.

03-03-2009, 03:09 AM	#22
bnwitt Senior Member Join Date: Nov 2008 Location: Southern California Posts: 409	email me a bnwitt at hotmail dot com and I will send you the schematic __________________ Warning! Some Electronics devices contain lethal voltages that can kill you. If you do not feel qualified to work with dangerous voltages, refer your repairs to a qualified technician. By giving you online advice, I am assuming no liability for any injury or damages you might incur through your own actions.

09-24-2009, 08:16 PM	#23
jorshb Junior Member Join Date: Sep 2009 Posts: 1	Frontman 212r Last night i was playing the guitar with my frontman212R and happens exactly the same when i turn the distortion channel on whether with the footswitch or the bottom on the front of amp the sounds go OFF !!! or sounds strange... ?? does anyone knows how to fix this ?? ?

01-21-2010, 09:13 AM	#24
davetutt Junior Member Join Date: Jan 2010 Posts: 1	Frontman issues Hi folks I have had several of these through my workshop. The loss of the channel has turned out to be either dry joints at the resistor (1k2 1watt) next to the main smoothing capacitor. I have yet to find any serious issue in the low level electronics of the amp. I have however found that the main rectifier diodes are less than reliable under load (all measure okay when removed from the board) and the only option is to replace them all. Likewise the down stream zener regulator for the op-amps and low level circuits (+-16 volts or so) seems to fail when the 5 watt resistors have dry joints and disconnect the supply. be aware that this can cause issues in some other parts of the circuitry especially if one supply line goes missing and is left on humming to itself! After all this time the speakers will be getting old and tired. I replace these with Celestion 12K100 drivers as they are significantly better. I also make two alterations to the cabinet to solve a number of rattles. These are a short back panel made from MDF or similar that doesn't cover all the back area and includes two holes of approximately 3 inches to allow the speakers to breath. The second change is a brace between the new back and the front baffle made from 3x2 timber. Also, the grill cloth slaps back onto the grill frame causing it to buzz, especially if you use a 7 string guitar which goes down to 55hz so packing out the grill fabric with a thin strip of door sealing foam stops this happening. Hope that helps. Any questions let me know. This is a great amp and so far i haven't found any issues that are too serious to fix!

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