Fender M-80 chorus problém

[warry]

Hello,

First I'm sorry for my englesh, but I'm french.
I have a Fender M-80 chorus with a trouble.
When I switch on the amp, the XF3 (CP15) is immediatly burned.

Please someone could help me?
Or just send me the shematics.

Thank you very much

[mbratch]

I did a little digging and found this one:

Fender M-80 Schematic (gif)

By the way, your English is very good. As understandable as most around these parts.

[vintagekiki]

Check CR52/CR53; C83; Q8/9; Q12/13

[mbratch]

Ah thanks vintagekiki. I posted the wrong M-80 schematic.

[warry]

Check CR52/CR53; C83; Q8/9; Q12/13

Thank you very much for your Answers.
I disconnected Q8 / 9 and Q12 /13 (all TIP142 &TIP147) and it's the same problem (XF3 burned).
So I will see the CR52 / 53 and C83.

Other tracks

Thanks for my english

[vintagekiki]

Remove Q8 / 9 and Q12/13. If XF3 burned again, check C83 (4700μF/ 50V) and CR52/CR53.
Also check that there is no short circuit between point -40VDC (TP4) and chassis
PS: About my English (sorry web translators)

[warry]

I think CR 52 is died, because, when I removed and tested it, she's "busy" .
Someone knows what is the caracteristics of CR52? It's just writed DII6A4
I want to change it.

[Jazz P Bass]

6A4 diode

6A4 is a 400 Vdc/ 6 amp diode.
Can you check diode. Is it shorted in both directios?
If not shorted, than it is o/k.
You need to find what is loading down your -40 volt rail.

[warry]

6A4 is a 400 Vdc/ 6 amp diode.
Can you check diode. Is it shorted in both directios?
If not shorted, than it is o/k.
You need to find what is loading down your -40 volt rail.

Yes CR52 is shorted (I didn' know the english world for "passante" in french"). So she is shorted in both directions. Monday I will buy one and see.
I will come back for say the results.

Thank's

[J M Fahey]

Bonjour wary.
Si vous en avez besoin, vous pouvez écrire en Français, quelques uns entre nous sommes Francophones et très fiers d' être ça.
Even so, if possible, English is preferred, for the benefit of the greatest amount of members.

[vintagekiki]

Testing a diode with a multimeter
http://www.kpsec.freeuk.com/multimtr.htm#diode
Correct diode conducts in one direction, and in the reverse direction has infinite resistance (testing with analog ohm meter x1 or x10)
When the diode check with a digital instrument in the conduct direction show a voltage of 0.65V to 07V. In the reverse direction will prove immeasurable value of diode voltage.
Advice. If one diode incorrect, change all 4 diodes. Check electrolyte capacitor 4700μF/ 50V.
Before starting voltage, be sure to check with ohm meter that there is no short circuit between TP4 (-40VDC) and chassis, and between TP3 (+40 VDC) and the chassis.

[olive2sing]

I had the same problem with a M80 chorus a few years ago and replaced the shorted diodes with a replacement from Mouser with a different part number. The new output transistors blew again. Make sure you use the same part number diodes, a conversion will not work. I learned the hard way, but the smoke was cool.

[Enzo]

If CR52 is shorted, please change CR53 at the same time. Even if it tests OK now.


When CR52 shorts, it becomes liike a piece of wire. ANd that leaves CR53 directly across one end of the transformer winding to the other. This can be very stressful on the part. SO for the low price of a new part, replace it - that will improve reliability of the repair.


before you put the TIP142/147 parts back in, make sure they are not shorted. If one of those failed, it could be responsible for the failure of CR52.

[warry]

If CR52 is shorted, please change CR53 at the same time. Even if it tests OK now.


When CR52 shorts, it becomes liike a piece of wire. ANd that leaves CR53 directly across one end of the transformer winding to the other. This can be very stressful on the part. SO for the low price of a new part, replace it - that will improve reliability of the repair.


before you put the TIP142/147 parts back in, make sure they are not shorted. If one of those failed, it could be responsible for the failure of CR52.

SO I will change the 4 diodes, with 4 diodes 6A4. And I will change the 2 TIP142 and 2 TIP147.
If I find exactly the same, I will change the C83 (4700μF/ 50V).

It's OK for every body?
I will tell you what news after.

PS: Pour J M Fahey (ou autre francophone), pourriez vous me traduire le dernier message, celui que j'ai copié, car je ne comprend pas tout le sens de al phrase, est les traducteurs internet encore moins. Merci

[J M Fahey]

Bien sûr warry.
Ça va bien pour pratiquer mon Français oxydé.

Originally Posted by Enzo View Post
If CR52 is shorted, please change CR53 at the same time. Even if it tests OK now.
When CR52 shorts, it becomes liike a piece of wire. ANd that leaves CR53 directly across one end of the transformer winding to the other. This can be very stressful on the part. SO for the low price of a new part, replace it - that will improve reliability of the repair.
before you put the TIP142/147 parts back in, make sure they are not shorted. If one of those failed, it could be responsible for the failure of CR52.

veut dire:
À l'origine Posté par Enzo Voire:
Si CR52 est court-circuité ("passant"), changez s'il vous plaît CR53 en même temps. Même s'il évalue/mesure bien maintenant.
Quand CR52 court-circuite, cela devient comme un morceau de fil. Et cela laisse CR53 directement connecté d'une fin du transformateur à l'autre. Cela peut être très stressant sur le diode. AINSI pour le prix bas d'une nouvelle pièce, remplacez-le - qui améliorera l'intégrité de la réparation. (Personnellement, je changerai les 4 diodes)
avant que vous remettez les transistors TIP142/147 dans le amplificateur, assurez-vous qu'ils ne sont pas court-circuités. (cherchez ici "testing diodes and transistors") Si un d'entre ceux a échoué, cela pourrait être responsable de l'échec de CR52.
Bonne chance
PS: j'ai cherché "comme tester transistors" en Français avec mauvaises résultats.
Je vais dessiner e poster ici comment tester les TIP142/147, ou les résultats sont "fous", car ils sont des Darlingtons e pour compliquer tout, ils ont des diodes de protection "inverse" émetteur-collecteur.