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Messages - dlbraly

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16
Amplifier Discussion / Re: Frontman 212R
« on: May 23, 2020, 11:44:52 AM »
I get 29 VDC measuring across the speaker leads.
Can I leave the speakers unplugged to go back and retest the test points?
OR
I assume I need a load since to complete the circuit. Do I just use a 4 ohm resister?

After the Rectifier - That is the big diodes right?
Does that mean put my ground lead of my DVM at TP4 or TP3 to measure DC Voltage? I assume TP4.

Thank You

17
Amplifier Discussion / Re: Frontman 212R
« on: May 23, 2020, 09:51:58 AM »
Hum:
It is a loud hum, Speakers vibrate, but go in one direction from rest. No output with an input.
Can I test the circuit with the speakers unplugged? Maybe with a 4 Ohm resister or something?

Rail +-47:
Is the rail the output of the transformer? When I measure the secondary of the transformer i get 64 VAC (red wire to red). The center tap gets 32 VAC (either red wire to yellow).

Confused Testing - I am a Novice. I'm most likely doing something wrong. I was using Chassis ground. Should I be using something else? Do I use a leg of the secondary?

Also, I just noticed I had all the pots turned all the way to the left - I'm suppose to have them at 50% right?

Thank You for your advice

18
Amplifier Discussion / Re: Frontman 212R
« on: May 22, 2020, 11:08:47 PM »
yeah, Maybe I put that switch in wrong, or it is not the correct switch for this.
I was thinking I made sure it acted the same as what I took out.


Test Point - Actual Voltage - Supposed to be
TP1          - 29VAC           - 32 VAC
TP2          - 29VAC           - 32 VAC
TP3          - 38 VDC          - 41 VDC
TP4 -        -31 VDC          --41 VDC

T20 pannelSwitch NormCH - .67 VDC - .75 VDC
T20 PannelSwitch DriveCH - 2.14 VDC - 2.3 VDC

T21 NormCH - 1.2 VDC      - 1.2 VDC
T21 DriveCH - 1.2 VDC       - 1.2 VDC

T22 NormCH - 15.32 VDC    - 16 VDC
T22 DriveCh - -13.73 VDC - -16 VDC

T23 NormCH - -15.55 -       -16 VDC
T23 DriveCh - -0.2 VDC      - 0 VDC

T24 PannelSwitch S1 Drive - 0.93 VDC - 2.4 VDC
T24 MoreDrive - -0.95 - -9.3 VDC

T25 NormCH - -15.2 VDC   --16 VDC
T25 NormCh - 15.2 VDC     - 16 VDC

T26 NormCH - -1.9 VDC      - -11.8 VDC
T26 DriveCH - -2.9 VDC       - -5.14 VDC
T26 MoreDrive - -7.2 VDC      - -4.82 VDC

T27 NormCH - -15.6 VDC      - 0 VDC
T27 DriveCH - 0 VDC            - 0 VDC
T27 MoreDriveCH - -15.6 VDC - -16 VDC

19
Amplifier Discussion / Re: Accutronics Belton Reverb Module
« on: May 22, 2020, 10:26:59 PM »
I like those Yamaha amps Keith.

20
Amplifier Discussion / Re: Frontman 212R
« on: May 22, 2020, 10:25:09 PM »
S1 More Drive switch
Thanks

21
Amplifier Discussion / Frontman 212R
« on: May 22, 2020, 08:24:09 PM »
Hello,
Novice here.

I have a Frontman 212R I bought 2 years ago in hopes of repairing. I replaced a bad switch back then that would not stay in when pressed.
Just getting back around to it again.

It has had a loud hum since i got it. (I will read the post on hum, that is a TON of info)

I do not have a tone generator, so I tested only the test points the schematic (attached) said I did not need to use one. Test point 1-4 and Test points 20-27

Test points were normal except:
TP 24 normal channel was only .93 VDC More drive was - .95 VDC (it should be -2.4 and -9.3)
TP 26 NormCH -1.9, DriveCh -2.0, and more drive -7.2 VDC (it should be -11.8, -5.14, -4.82)
TP 27 NormCh -15.6, Drive 0, More Drive -15.6 VDC (it should be 0, 0, -16)

Any help and advice would be greatly appreciated.

Thank You

22
Schematics and Layouts / Re: Frontman 212r
« on: February 19, 2019, 09:05:46 AM »
Thank You,
I have not had a chance yet to call Fender to ask them.
I will let you know what I find out.

23
Schematics and Layouts / Frontman 212r
« on: February 17, 2019, 12:11:35 PM »
Hello,

I'm having trouble finding the part number to Drive / More drive switch.
S1 on the schematic.

Can you tell me the correct part number to order?

I ordered the wrong one 0028091049 online, its a little too small.

Thank you for your help and advise.

24
Schematics and Layouts / Re: Adding Bluetooth to lm386amp
« on: August 05, 2018, 10:44:43 AM »
Good Question  :dbtu:
It would be pretty cool to be able to add a bluetooth module.
I see "how to" on installing something like that inside a radio.
Neat feature to play along to some music.

25
cool, thanks for sharing. :dbtu:

26
Amplifier Discussion / Re: Yamaha G100-112 - Journey
« on: July 28, 2018, 07:00:23 PM »
That Yamaha Amp really sounds good.  :dbtu:
My Dad asked me if I wanted to use it a little longer. I told him he better take it because all I'm dong is playing on it. I'm not getting my other stuff done.

Yamaha really made a sturdy amp. the wood in the cab was real thick and heavy!
Im curious if the Series II and III are as heavy duty.
Anyone have any idea?
What are your thoughts on Yamaha Amps? Good, Bad, just OK?

I blogged on it. Nothing more that is not posted here.
My Blog


27
I did not see knobs like yours on their page, so I emailed them. Lets see what they say.
I attached your image to the email.

"
Date: Sun, Jul 22, 2018 at 1:53 PM
Subject: Yamaha YTA-95
To: grinnell@surplussales.com

Hello,
We are looking for some Yamaha YTA-95 guitar amp knobs.
Do you have anything like that?

----
Take Care,
Dave
"

28
Those are cool looking.
Could you take a regular knob cut a notch and paint it? You may need to do a whole set so they look the same.
The basic shape looks like these.

29
Amplifier Discussion / Re: Yamaha G100-112 - Journey
« on: July 21, 2018, 11:55:53 PM »
OK, so TR206 and TR207 can cause that popping!
I removed them, and I cleaned the pots.
Enzo rocks! I should have just listened to him in the first place. Thanks.

I will mess around with it some more, and to make sure nothing else is wrong with it. I also need to do some very minor cosmetic stuff to it.
There is a tiny tear that I don't want to get any bigger.
and someone replaced a pot, but put one in that the shaft was too big, and just cut it off to fit. but the knob doesn't stay one. I'm going to try and cut a slit it in it since it now longer has one.

I think my Dad will be happy with it.

30
Amplifier Discussion / Re: Yamaha G100-112 - Journey
« on: July 21, 2018, 06:17:57 PM »
Picked up some thermal Paste, got the amp back together.
I bought 2 NTE458 transistors to replace the bad transistor 2SK30A (replaced the pair of them).
I did not not try the amp without the transistors like Enzo suggested. I was there getting the paste...
The amp is now loud like it should be.

BUT,
There is a very loud popping noise. Ive twisted all the pots and it doesn't seem to make a difference in the popping.
Turn the amp on with or without guitar after about 15 or 20 seconds it starts a loud sporadic popping. Turn the amp off, then back on another 15 seconds or so it starts again.

I did notice that sometimes when you turn the amp off, you can hear some static sound from the speaker for a few seconds. Im not sure if that is normal for this amp.

Would the 2 transistors I replaced (TR206 and TR207) cause that type of fault?

I have NOT done the adjustments yet that the service manual says to do. Figured I'd post here first. Then go back in and see if I can do that.

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