Motorola XM501 - Cap Kit Questions inside

Superully

Active member
Joined
Apr 22, 2008
Messages
1,749
Reaction score
11
Location
Lauda, Baden-Wuerttemberg, Germany
the picture of my motorola xm501 (displaying grand trak 10) is too bright and distorted - adjusting the screen didn't make it much better :(

5300849262_76839217e8_b_d.jpg


that's why i've decided to do a cap kit first to see if it solves the problem. the kit from bob roberts includes 9 capacitors, 7 of which go on the circuit board. however, i was only able to find 6 of those capacitors, the one labeled C16 on the pcb (which is supposed to be 1μf 15V cap) doesn't look like a capacitor to me at all. have a look at the following picture, i've marked it with an arrow. is that a capacitor? if not, where's the real C16?

on the picture you can also find the 6 other capacitors (which need to be replaced) marked with green PLUS there are more capacitors on that board which i marked in red.

question: do i have to replace those capacitors as well (after all, they weren't included in the cap kit from BR)? what do you think? replace 'em or leave 'em?

5300243925_2f9415f56d_b_d.jpg
 
Your arrow is actually pointing to C17 not C16.

C16 is the orange-red dipped tantalum capacitor to the left of your arrow.
 
i see, thx for clearing this up. and this tantalum capacitor needs to be replaced with a "normal" one? where's + and - on that thingy?

what about the other caps i numbered in red?

The caps in red are film caps.....C26 looks like (maybe) polypropylene....the others look like polyester.

Edward
 
and what does that mean? can't (or don't) they (have to) be replaced?

It's very uncommon to have a film cap go bad. It can happen, but very unlikely.

Your problem looks more like a problem with the big "can" cap(s)....I can't remember if XM's have one or two.

Edward
 
Your problem looks more like a problem with the big "can" cap(s)....I can't remember if XM's have one or two.

those are the ones which are not on the circuit board and which are not included in bob's cap kits, right? i haven't had the time to look at them, because i didn't know until recently they even existed ;). i'll check them out tomorrow and report back ...

as for the C16 tantalum capacitor: how do i know the correct orientation? i can't see any markings on it nor on the pcb!
 
those are the ones which are not on the circuit board and which are not included in bob's cap kits, right? i haven't had the time to look at them, because i didn't know until recently they even existed ;). i'll check them out tomorrow and report back ...

as for the C16 tantalum capacitor: how do i know the correct orientation? i can't see any markings on it nor on the pcb!

Yup, big cap(s) mounted to the metal pan.

Regarding the tantalum....it should have a little "+" sign stamped on one side designating the positive leg (if it hasn't rubbed off from time/age).
If the schematics I'm looking at are correct....negative side goes to resistor R25.

Edward
 
It looks like the cap is not marked on the board but the manual has the - side towards the edge of the PCB. The cap with the red dot is C16 and I marked the polarity.
 

Attachments

  • XM501 c16.jpg
    XM501 c16.jpg
    97.9 KB · Views: 123
ok, did the cap kit on the pcb today

5303023517_8ecda6c97e_b_d.jpg


however, there are two axial capacitors still left. in a forum posting i found the following:

- C50 can be found on the small plugin card. plugin card? where is that?
- C51 is under the chassis. where exactly?

here's a picture of the right side of the monitor frame

5303616602_4629bac155_b_d.jpg


and here's a picture of the left side with the green arrow pointing at the big can (is that C43 or C47?)

the left side again - this time viewed from underneath with the green arrow once again pointing at the big can

5303023189_7263ae6fa3_b_d.jpg


here are my questions:

- where are C50 / C51?
- is it possible that C50 / C51 are only present on the XM701, but not the XM501?
- i was told that there are TWO big cans on the monitor. however, i can only find one. could this also be an XM501/701 issue?
- what is the function of that big can?

i'll put the pcb back in together tomorrow, can't wait to find out the results of the cap kit! and of course i can't wait to read your answers to my questions ;)
 
I'm not really familiar with differences between a 501 and 701, but maybe this will help....

C43 is a multi cap (3 in 1) 400uf/125v - 600uf/50v - 20uf/200v
C47 is just a single value cap 5000uf/20v

So verify yours by looking at the actual values on the can itself. (if still legible)

The plug in card should be right in front of the huge transformer. (C50)

C51 is shown on the bottom of the chassis like you mentioned.
 

Attachments

  • Motorola.jpg
    Motorola.jpg
    101.5 KB · Views: 97
thx a lot for clearing things up - i appreciate your efforts!
i've just looked at a spare gun fight monitor i have here and it looks almost like the one you pictured. however, when i look at my gran trak 10 monitor, the pcb is identical, but the rest is not. here's another picture from the back - completely different (pcb still removed from the middle section). also compare it with the other pictures of it i've posted above. the only thing i could find is the "big can". is it such an important part that i should replace it?

5304604588_a2c29abfe9_b_d.jpg
 
The only difrence between the 501 and 701 is the tube size 501=19" 701=23". The plugin card is used for volume control and generating a +5v. Both features are rarely used, I've never seen them used, so it is not uncommon to have a monitor without the card and the second can cap which is also used to generate the +5v.

So you may not have a C50 and it looks like KevinMullins has posted the location C51 already.
 
So you may not have a C50 and it looks like KevinMullins has posted the location C51 already.

i have looked everywhere underneath the monitor - no C51. to be honest, i don't even know if the entire monitor is a motorola, it could also be that they just used the motorola pcb. that's probably why the rest looks different ...
 
Oh that's right the Gran trak used the xm-700 or xm-500 for the trak 10. It's the basicly the same monitor but the chassis is diffrent and a lot more cramped to work on. I believe everything is wired the same but I'm not 100% sure my Trak 10 is in storage. It doesn't have the plugin card or the 5000mf can cap

I think the C51 might be located on one of the sides, on the inside. It has been a long time since i capped this monitor. but I seem to remember one there that was a pain to replace
 
Last edited:
yea you need C51. I edited my last post. I think I remember it being on the side of the chasis on the inside. Do you see any caps there?
 
yea you need C51. I think I remember it being on the side of the chasis on the inside. Do you see any caps there?

basically all there is can be seen on my pictures above. there is one cap (is it a cap?) on the right side of the monitor chassis (on the corresponding picture it is labelled 1/630). don't know if this is the correct one. if not, i'll have to check tomorrow, because it's already pretty late over here in germany and i have to go to my mother's place where the cab is stored atm.

thx for helping me out!!!
 
Back
Top Bottom