It is currently Mon Mar 16, 2020 10:38 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 110 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 8  Next
Go to page Previous  1, 2, 3, 4, 5 ... 8  Next
Author Message
Post subject:
Posted: Mon Sep 06, 2010 1:45 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
The shield (as its name indicates it) is connected to the ground, the other wire (called soul in french) is connected to the input "n°2" and R4 (on D-8 area on the schematic).

For the reverb, there are 2 RCA (may be retroverbial can confirm on this version) connected to the tank. disconnect both from the amp and let me know.

By the way, the "return input" should work now, isn't it?

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Fender Play Winter Sale 2020
Post subject:
Posted: Mon Sep 06, 2010 1:54 pm
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
Well, now I am blowing fuses. When I switch the power on there is a loud hum and the 4A 250v fuse will blow. I must have a short somewhere but I can't find it. I think this happened because I got the red wires for CP4 and CP5 mixed. It looks like they go to a transformer mounted on the chassis. I hope I didn't do permanent damage because I was getting so close.


Top
Profile
Post subject:
Posted: Mon Sep 06, 2010 2:26 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
CP4 is bi-color isn'it? Red/Yellow

CP4 and CP5 shall not be connected together since CP4 is the middle of the AC transformer connected to the GND and CP5 and CP3 and opposite phases connected to the rectifying diodes.

D-7 and C-3 areas on page 2 of the link, please reconnect properly, the short was on AC section, there is probably no damage on the amplifier.

If you don't feel confident I think it is better to make it by a technician.

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Post subject:
Posted: Mon Sep 06, 2010 2:55 pm
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
Yes I connected the red/yellow CP4 GND to the CP 5 terminal by mistake. I have since reconnected properly but I still get the humming sound and the fuse will blow. I can't afford to take it to a technician.


Top
Profile
Post subject:
Posted: Mon Sep 06, 2010 3:02 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
Unsolder completly diodes CR53 /CR52 and CR54/CR55, please make a picture before with your camera or your phone in order to be able to reconnect after.

Let me know if the fuse blow again.

If you don't feel confident, let a tech to repair it.

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Post subject:
Posted: Mon Sep 06, 2010 3:11 pm
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
I have located diodes CR53 /CR52 and CR54/CR55. I have also made a picture. I am confident, I just am not knowledgeable. But you are extremely helpful and patient and it is amazing that you know all of this. Thank you and I will be back soon.


Top
Profile
Post subject:
Posted: Mon Sep 06, 2010 3:21 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
If the fuse is still blowing without the rectifier bridge then the transformer is probably dead;
I'm going to bed, it's midnight !

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Post subject:
Posted: Mon Sep 06, 2010 4:27 pm
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
All four Diodes removed and the hum is not there and the fuse did not blow. I replaced the 4 diodes and soldered them back in and of course I have the same problem of the humming noise and fuse blowing. It takes a few seconds for the fuse to blow so I cut the power when I hear the humming noise to save on fuses. Thank you for your help today and I hope that you get a good night of rest!


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 3:11 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
The transfo seems OK.

Before put back the diodes please measure them with the multimeter.

Position Diode Multimeter (kind of arrow with a vertical line at the end of the triangle)

2 tests per diode --> Red and black probes on the 2 opposite diodes pins and vice-versa. You should read 0.6V (or close) in forward and no leakage in reverse, if bip-bip or 0 the diode is in short circuit.

Borring therory --> (0.6V is the normal forward voltage for PN junction for small current, when you apply direct voltage the "space charge" decreases and allows current within the PN juction, you apply reverse voltage the "space charge" at the PN junction increases and no current can go through)


Let me know

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 6:41 am
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
CR 55 = 539 Forward Bias ; 1 Reverse Bias

CR 54 = 492 Forward Bias ; 1 reverse Bias

CR 53 = 450 Forward Bias ; 1 Reverse Bias

CR 52 = 440 Forward Bias ; 1 Reverse Bias

No bip-bip, but I am thinking that the readings are probably .5, .5 , 4.5, 4.4.

My meter may have the decimal in the wrong place but I do not know for sure. There is no way to change it.


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 7:25 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
Diodes bridge seems OK, what is your multimeter?

Test CR56 and CR57 --> Zener diode (it should be similar but in the other side) Don't forget to take a picture to make sure to not make a mistake.

By the way When I make it, I desold only 1 pin of the diode.

Don't supply you amp before finding the short circuit.

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 7:57 am
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
CR 56 = 715 ; 1

CR 57 = 733 ; 1

My meter is a very cheap Greenlee http://www.greenlee.com/product/DM-20.html


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 9:02 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
Zeners seem OK.

Test Q11/12/13/14 power transistors. You shall see 2 junctions base-collector and base-emiter, no short. (2 NPN and 2 PNP)

Do not reconnect the power transistors.

Let me know.

As usual take picture to make sure about rebuild.

( http://www.jeulin.fr/fr/a-a1024014-edc1 ... stor-.html )

Sorry for french

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 10:09 am
Offline
Hobbyist
Hobbyist

Joined: Fri Mar 12, 2010 7:04 am
Posts: 60
Q11 = 570 ; 1 Testing B - C
Q12 = 467 ; 1 Testing B - E
Q13 = 510 ; 1 Testing B - E
Q14 = 0 ; 0 Testing B - E however when I test B - C on Q14 I get 668 ; 1


Top
Profile
Post subject:
Posted: Tue Sep 07, 2010 11:56 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat May 08, 2010 4:31 am
Posts: 411
Location: France
It seems that Q14 is Base-Emitter short cut --> Dead, PN junction broken

Bad news.

:( :( :( :(

It is a common PNP darlington transistor with complementary TIP142 NPN
I'm not sure, but I recommand to change Q12 and Q14 and you have to order matched one; I'm not sure about matched one because R114 and R115 may be enough to balance enough the push-pull stage (As I didn't design this amp I don't know and it's too long to make complete simulation characterization).
Here is the datasheet :http://www.datasheetcatalog.com/datasheets_pdf/T/I/P/1/TIP147.shtml

Before new test, check Q9 and Q10, CR33/CR34 and CR25 to CR32.

If all are OK, supply just to know if the short disapears

If OK, reconnect only Q11 and Q13 and supply just to know if the short desappear.

Let me know;

If you have doudt, contact a tech and take picture to avoid mistakes.[/img]

_________________
Tissan '52 Tele RI & Washburn Hawk 1980, Epiphone Casino MIK, Blues Deluxe RI & VOX ...


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 110 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 8  Next
Go to page Previous  1, 2, 3, 4, 5 ... 8  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: